raduino_v2.04.ino

/**
   Raduino_v2.04 for BITX40 - Allard Munters PE1NWL (pe1nwl@gooddx.net)

   This source file is under General Public License version 3.

   Most source code are meant to be understood by the compilers and the computers.
   Code that has to be hackable needs to be well understood and properly documented.
   Donald Knuth coined the term Literate Programming to indicate code that is written be
   easily read and understood.

   The Raduino is a small board that includes the Arduino Nano, a 16x2 LCD display and
   an Si5351a frequency synthesizer. This board is manufactured by Paradigm Ecomm Pvt Ltd.

   To learn more about Arduino you may visit www.arduino.cc.

   The Arduino works by first executing the code in a routine called setup() and then it
   repeatedly keeps calling loop() forever. All the initialization code is kept in setup()
   and code to continuously sense the tuning knob, the function button, transmit/receive,
   etc is all in the loop() routine. If you wish to study the code top down, then scroll
   to the bottom of this file and read your way up.

   First we define all user parameters. The parameter values can be changed by the user
   via SETTINGS menu, and are stored in EEPROM.
   The parameters values will be set to initial 'factory' settings after each
   version upgrade, or when the Function Button is kept pressed during power on.
   It is also possible to manually edit the values below. After that, initialize the
   settings to the new values by keeping the F-Button pressed during power on.
*/

// *** USER PARAMETERS ***
#define MY_CALLSIGN ""            // callsign here will display on line 2 when otherwise blank (tks Richard, VE3YSH)
#define FAST_TUNE_DELAY 300       // fast tuning step delay in ms (when tuning pot is at the upper or lower limit)(tks Bob, N4FV)

// tuning range parameters
#define MIN_FREQ 7000000UL        // absolute minimum tuning frequency in Hz
#define MAX_FREQ 7300000UL        // absolute maximum tuning frequency in Hz
#define TUNING_POT_SPAN 50        // tuning pot span in kHz [accepted range 10-500 kHz]
// recommended pot span for a 1-turn pot: 50kHz, for a 10-turn pot: 100 to 200kHz
// recommended pot span when radio is used mainly for CW: 10 to 25 kHz

// USB/LSB parameters
#define CAL_VALUE 1575            // Initial VFO calibration value: 180 ppm
#define BFO_OFFSET_USB -2200      // BFO offset for USB in Hz [accepted range -3500Hz to -1250Hz]
#define BFO_OFFSET_CWL -130       // BFO offset for CWL in Hz [accepted range -750 Hz to 0Hz]
#define BFO_OFFSET_CWU -2070      // BFO offset for CWU in Hz [accepted range -3500Hz to -500Hz]

// CW parameters
#define CW_SHIFT 800              // RX shift in CW mode in Hz, equal to sidetone pitch [accepted range 200-1200 Hz]
#define SEMI_QSK true             // whether we use semi-QSK (true) or manual PTT (false)
#define CW_TIMEOUT 350            // time delay in ms before radio goes back to receive [accepted range 10-1000 ms]

// CW keyer parameters
#define CW_KEY_TYPE 0             // type of CW-key (0:straight, 1:paddle, 2:rev. paddle, 3:bug, 4:rev. bug)
#define CW_SPEED 16               // CW keyer speed in words per minute [accepted range 1-50 WPM]
#define AUTOSPACE false           // whether or not auto-space is enabled [accepted values: true or false]
#define DIT_DELAY 5               // debounce delay (ms) for DIT contact (affects the DIT paddle sensitivity)
#define DAH_DELAY 15              // debounce delay (ms) for DAH contact (affects the DAH paddle sensitivity)

// Capacitive touch keyer
#define CAP_SENSITIVITY 0         // capacitive touch keyer sensitivity 0 (OFF) [accepted range 0-25]

// frequency scanning parameters
#define SCAN_START 7100           // Scan start frequency in kHz [accepted range MIN_FREQ - MAX_FREQ, see above]
#define SCAN_STOP 7150            // Scan stop frequency in kHz [accepted range SCAN_START - MAX_FREQ, see above]
#define SCAN_STEP 1000            // Scan step size in Hz [accepted range 50Hz to 10000Hz]
#define SCAN_STEP_DELAY 500       // Scan step delay in ms [accepted range 0-2000 ms]

// Function Button
#define CLICK_DELAY 1500          // max time (in ms) between function button clicks

// RX-TX burst prevention
#define TX_DELAY 65               // delay (ms) to prevent spurious burst that is emitted when switching from RX to TX

// digital BFO
#define BFOFREQ (11998800UL)      // initial (uncalibrated) BFO frequency (Hz)

// all variables that will be stored in EEPROM are contained in this 'struct':
struct userparameters {
  byte raduino_version;                            // version identifier
  int cal = CAL_VALUE;                             // VFO calibration value
  unsigned long bfo_freq = BFOFREQ;                // BFO frequency (Hz) for LSB mode
  int bfo_offset_usb = BFO_OFFSET_USB;             // BFO offset in Hz for USB mode
  int bfo_offset_cwl = BFO_OFFSET_CWL;             // BFO offset in Hz for CWL mode
  int bfo_offset_cwu = BFO_OFFSET_CWU;             // BFO offset in Hz for CWU mode
  bool PBT_enabled = false;                        // whether or not the PBT pot is installed
  byte wpm = CW_SPEED;                             // CW keyer speed (words per minute)
  bool semiQSK = SEMI_QSK;                         // whether semi QSK is ON or OFF
  unsigned int POT_SPAN = TUNING_POT_SPAN;         // tuning pot span (kHz)
  unsigned int CW_OFFSET = CW_SHIFT;               // RX shift (Hz) in CW mode, equal to side tone pitch
  unsigned long vfoA = 7125000UL;                  // frequency of VFO A
  unsigned long vfoB = 7125000UL;                  // frequency of VFO B
  byte mode_A = 0;                                 // operating mode of VFO A
  byte mode_B = 0;                                 // operating mode of VFO B
  bool vfoActive = false;                          // currently active VFO (A = false, B = true)
  bool splitOn = false;                            // whether SPLIT is ON or OFF
  unsigned int scan_start_freq = SCAN_START;       // scan start frequency (kHz)
  unsigned int scan_stop_freq = SCAN_STOP;         // scan stop frequency (kHz)
  unsigned int scan_step_freq = SCAN_STEP;         // scan step size (Hz)
  unsigned int scan_step_delay = SCAN_STEP_DELAY;  // scan step delay (ms)
  unsigned int QSK_DELAY = CW_TIMEOUT;             // word [accepted range 10-1000 ms]
  byte key_type = CW_KEY_TYPE;                     // CW key type (0:straight, 1:paddle, 2:rev. paddle, 3:bug, 4:rev. bug)
  unsigned long LOWEST_FREQ = MIN_FREQ;            // absolute minimum dial frequency (Hz)
  unsigned long HIGHEST_FREQ = MAX_FREQ;           // absolute maximum dial frequency (Hz)
  bool autospace = AUTOSPACE;                      // whether auto character space is ON or OFF
  byte cap_sens = CAP_SENSITIVITY;                 // sensitivity of the touch keyer sensors
  bool vfo_high = true;                            // whether the VFO is on the high side (true) or on the low side (false) of the IF
};

// we can access each of the variables inside the above struct by "u.variablename"
struct userparameters u;

/**
   Below are the libraries to be included for building the Raduino
   The EEPROM library is used to store settings like the frequency memory, calibration data, etc.
*/

#include <EEPROM.h>

/**
    The Wire.h library is used to talk to the Si5351 and we also declare an instance of
    Si5351 object to control the clocks.
*/
#include <Wire.h>

/**
    The PinChangeInterrupt.h library is used for handling interrupts
*/
#include <PinChangeInterrupt.h> // https://github.com/NicoHood/PinChangeInterrupt

/**
    The main chip which generates upto three oscillators of various frequencies in the
    Raduino is the Si5351a. To learn more about Si5351a you can download the datasheet
    from www.silabs.com although, strictly speaking it is not a requirement to understand this code.

    We no longer use the standard SI5351 library because of its huge overhead due to many unused
    features consuming a lot of program space. Instead of depending on an external library we now use
    Jerry Gaffke's, KE7ER, lightweight standalone mimimalist "si5351bx" routines (see further down the
    code). Here are some defines and declarations used by Jerry's routines:
*/

#define BB0(x) ((uint8_t)x)             // Bust int32 into Bytes
#define BB1(x) ((uint8_t)(x>>8))
#define BB2(x) ((uint8_t)(x>>16))

#define SI5351BX_ADDR 0x60              // I2C address of Si5351   (typical)
#define SI5351BX_XTALPF 2               // 1:6pf  2:8pf  3:10pf

// If using 27mhz crystal, set XTAL=27000000, MSA=33.  Then vco=891mhz
#define SI5351BX_XTAL 25000000          // Crystal freq in Hz
#define SI5351BX_MSA  35                // VCOA is at 25mhz*35 = 875mhz

// User program may have reason to poke new values into these 3 RAM variables
uint32_t si5351bx_vcoa = (SI5351BX_XTAL*SI5351BX_MSA);  // 25mhzXtal calibrate
uint8_t  si5351bx_rdiv = 0;             // 0-7, CLK pin sees fout/(2**rdiv)
uint8_t  si5351bx_drive[3] = {1, 1, 1}; // 0=2ma 1=4ma 2=6ma 3=8ma for CLK 0,1,2
uint8_t  si5351bx_clken = 0xFF;         // Private, all CLK output drivers off

/**
   The Raduino board is the size of a standard 16x2 LCD panel. It has three connectors:

   First, is an 8 pin connector that provides +5v, GND and six analog input pins that can also be
   configured to be used as digital input or output pins. These are referred to as A0,A1,A2,
   A3,A6 and A7 pins. The A4 and A5 pins are missing from this connector as they are used to
   talk to the Si5351 over I2C protocol.

    A0     A1   A2   A3    GND    +5V   A6   A7
   BLACK BROWN RED ORANGE YELLOW GREEN BLUE VIOLET  (same color coding as used for resistors)

   Second is a 16 pin LCD connector. This connector is meant specifically for the standard 16x2
   LCD display in 4 bit mode. The 4 bit mode requires 4 data lines and two control lines to work:
   Lines used are : RESET, ENABLE, D4, D5, D6, D7
   We include the library and declare the configuration of the LCD panel too
*/

#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 10, 11, 12, 13);

/**
   The Arduino, unlike C/C++ on a regular computer with gigabytes of RAM, has very little memory.
   We have to be very careful with variables that are declared inside the functions as they are
   created in a memory region called the stack. The stack has just a few bytes of space on the Arduino
   if you declare large strings inside functions, they can easily exceed the capacity of the stack
   and mess up your programs.
   We circumvent this by declaring a few global buffers as  kitchen counters where we can
   slice and dice our strings. These strings are mostly used to control the display or handle
   the input and output from the USB port. We must keep a count of the bytes used while reading
   the serial port as we can easily run out of buffer space. This is done in the serial_in_count variable.
*/

char c[17], b[10], printBuff[2][17];

/**
   We need to carefully pick assignment of pin for various purposes.
   There are two sets of completely programmable pins on the Raduino.
   First, on the top of the board, in line with the LCD connector is an 8-pin connector
   that is largely meant for analog inputs and front-panel control. It has a regulated 5v output,
   ground and six pins. Each of these six pins can be individually programmed
   either as an analog input, a digital input or a digital output.
   The pins are assigned as follows:
          A0,   A1,  A2,  A3,   GND,   +5V,  A6,  A7
       pin 8     7    6    5     4       3    2    1 (connector P1)
        BLACK BROWN RED ORANGE YELLW  GREEN  BLUE VIOLET
        (while holding the board up so that back of the board faces you)

   Though, this can be assigned anyway, for this application of the Arduino, we will make the following
   assignment:

   A0 (digital input) for sensing the PTT. Connect to the output of U3 (LM7805) of the BITX40.
      This way the A0 input will see 0V (LOW) when PTT is not pressed, +5V (HIGH) when PTT is pressed.
   A1 (digital input) is to connect to a straight key, or to the 'Dit' contact of a paddle keyer. Open (HIGH) during key up, switch to ground (LOW) during key down.
   A2 not currently used
   A3 (digital input) is connected to a push button that can momentarily ground this line. This Function Button will be used to switch between different modes, etc.
   A4 (already in use for talking to the SI5351)
   A5 (already in use for talking to the SI5351)
   A6 (analog input) iis connected to a center pin of good quality 100K or 10K linear potentiometer with the two other ends connected to
       ground and +5v lines available on the connector. This implements the PBT mechanism.
   A7 (analog input) is connected to a center pin of good quality 100K or 10K linear (preferably 10-turn) potentiometer with the two other ends connected to
       ground and +5v lines available on the connector. This implements the TUNING mechanism.
*/

#define PTT_SENSE (A0)
#define KEY (A1)
#define FBUTTON (A3)
#define PBT (A6)
#define ANALOG_TUNING (A7)

/**
    The second set of 16 pins on the bottom connector P3 have the three clock outputs and the digital lines to control the rig.
    This assignment is as follows :
      Pin   1   2    3    4    5    6    7    8    9    10   11   12   13   14   15   16  (connector P3)
         +12V +12V CLK2  GND  GND CLK1  GND  GND  CLK0  GND  D2   D3   D4   D5   D6   D7
    These too are flexible with what you may do with them, for the Raduino, we use them to :

    output D2 - PULSE : is used for the capacitive touch keyer
    input D3  - DAH : is connected to the 'Dah' contact of an paddle keyer (switch to ground).
    input D4  - SPOT : is connected to a push button that can momentarily ground this line. When the SPOT button is pressed a sidetone will be generated for zero beat tuning.
    output D5 - CW_TONE : Side tone output
    output D6 - CW_CARRIER line : turns on the carrier for CW
    output D7 - TX_RX line : Switches between Transmit and Receive in CW mode
*/

#define PULSE (2)
#define DAH (3)
#define SPOT (4)
#define CW_TONE (5)
#define CW_CARRIER (6)
#define TX_RX (7)

bool TXRX_installed = true; // whether or not the TX_RX mod (PTT bypass transistor) is installed (set automatically at startup)

/**
   The Raduino supports two VFOs : A and B and receiver incremental tuning (RIT).
   we define a variables to hold the frequency of the two VFOs, RIT, SPLIT
   the rit offset as well as status of the RIT

   To use this facility, wire up push button on A3 line of the control connector (Function Button)
*/

bool ritOn = false;             // whether or not the RIT is on
int RIToffset = 0;              // RIT offset (Hz)
int RIT = 0;                    // actual RIT offset that is applied during RX when RIT is on
int RIT_old;

bool firstrun = true;
char clicks;                    // counter for function button clicks
bool locked = false;            // whether or not the dial is locked
byte param;

/**
  Raduino has 4 modes of operation:
*/

#define LSB (0)
#define USB (1)
#define CWL (2)
#define CWU (3)

/**
   Raduino needs to keep track of current state of the transceiver. These are a few variables that do it
*/
unsigned long vfoA;               // the frequency (Hz) of VFO A
unsigned long vfoB;               // the frequency (Hz) of VFO B
byte mode = LSB;                  // mode of the currently active VFO
unsigned long bfo_freq;           // the frequency (Hz) of the BFO
bool vfo_high;                    // whether the VFO is on the low or on the high side of the IF
int PBT_offset = 0;               // the offset applied to the BFO by the PBT pot
int PBT_offset_old = 0;
bool inTx = false;                // whether or not we are in transmit mode
bool keyDown = false;             // whether we have a key up or key down
unsigned long TimeOut = 0;        // time in ms since last key down
volatile bool TXstart = false;    // this flag will be set by the ISR as soon as the PTT is keyed

//some variables used for the autokeyer function:

bool keyeron = false;        // will be true while auto-keying
unsigned long released = 0;
bool ditlatch = false;
bool dahlatch = false;
byte gap = 1;                // space between elements (1) or characters (3)
unsigned long dit;
unsigned long dah;
unsigned long space = 0;

// some variable used by the capacitive touch keyer:

bool CapTouch_installed = true;  // whether or not the capacitive touch modification is installed (detected automatically during startup)
byte base_sens_KEY;              // base delay (in us) when DIT pad is NOT touched (measured automatically by touch sensor calibration routine)
byte base_sens_DAH;              // base delay (in us) when DAH pad is NOT touched (measured automatically by touch sensor calibration routine)
bool capaKEY = false;            // true when DIT pad is touched
bool capaDAH = false;            // true when DAH pad is touched

/**
    Tks Pavel CO7WT:
    Use pointers for reversing the behaviour of the dit/dah paddles, this way we can simply
    refer to them as two paddles regardless it's normal or reversed
    Macros don't like pointers, so we create two byte vars to hold the values
**/

byte _key = KEY;
byte _dah = DAH;
byte *paddleDIT = &_key;         // Paddle DIT bind to KEY
byte *paddleDAH = &_dah;         // Paddle DAH bind to DAH

/** Tuning Mechanism of the Raduino
    We use a linear pot that has two ends connected to +5 and the ground. the middle wiper
    is connected to ANALOG_TUNNING pin. Depending upon the position of the wiper, the
    reading can be anywhere from 0 to 1023.
    If we want to use a multi-turn potentiometer covering 500 kHz and a step
    size of 50 Hz we need 10,000 steps which is about 10x more than the steps that the ADC
    provides. Arduino's ADC has 10 bits which results in 1024 steps only.
    We can artificially expand the number of steps by a factor 10 by oversampling 100 times.
    As a result we get 10240 steps.
    The tuning control works in steps of 50Hz each for every increment between 0 and 10000.
    Hence the turning the pot fully from one end to the other will cover 50 x 10000 = 500 KHz.
    But if we use the standard 1-turn pot, then a tuning range of 500 kHz would be too much.
    (tuning would become very touchy). In the SETTINGS menu we can limit the pot span
    depending on the potentiometer used and the band section of interest. Tuning beyond the
    limits is still possible by the fast 'scan-up' and 'scan-down' mode at the end of the pot.
    At the two ends, that is, the tuning starts stepping up or down in 10 KHz steps.
    To stop the scanning the pot is moved back from the edge.
*/

unsigned long baseTune = 7100000UL; // frequency (Hz) when tuning pot is at minimum position
int old_knob = 0;
int RXshift = 0;            // the actual frequency shift that is applied during RX depending on the operation mode
unsigned long frequency;    // the 'dial' frequency as shown on the display
int fine = 0;               // fine tune offset (Hz)

/**
   The raduino has multiple RUN-modes:
*/
#define RUN_NORMAL (0)      // normal operation
#define RUN_CALIBRATE (1)   // calibrate VFO frequency in LSB mode
#define RUN_TUNERANGE (2)   // set the range of the tuning pot
#define RUN_CWOFFSET (3)    // set the CW offset (=sidetone pitch)
#define RUN_SCAN (4)        // frequency scanning mode
#define RUN_SCAN_PARAMS (5) // set scan parameters
#define RUN_MONITOR (6)     // frequency scanning mode
#define RUN_FINETUNING (7)  // fine tuning mode

byte RUNmode = RUN_NORMAL;

/** *************  SI5315 routines - tks Jerry Gaffke, KE7ER   ***********************

   An minimalist standalone set of Si5351 routines.
   VCOA is fixed at 875mhz, VCOB not used.
   The output msynth dividers are used to generate 3 independent clocks
   with 1hz resolution to any frequency between 4khz and 109mhz.

   Usage:
   Call si5351bx_init() once at startup with no args;
   Call si5351bx_setfreq(clknum, freq) each time one of the
   three output CLK pins is to be updated to a new frequency.
   A freq of 0 serves to shut down that output clock.

   The global variable si5351bx_vcoa starts out equal to the nominal VCOA
   frequency of 25mhz*35 = 875000000 Hz.  To correct for 25mhz crystal errors,
   the user can adjust this value.  The vco frequency will not change but
   the number used for the (a+b/c) output msynth calculations is affected.
   Example:  We call for a 5mhz signal, but it measures to be 5.001mhz.
   So the actual vcoa frequency is 875mhz*5.001/5.000 = 875175000 Hz,
   To correct for this error:     si5351bx_vcoa=875175000;

   Most users will never need to generate clocks below 500khz.
   But it is possible to do so by loading a value between 0 and 7 into
   the global variable si5351bx_rdiv, be sure to return it to a value of 0
   before setting some other CLK output pin.  The affected clock will be
   divided down by a power of two defined by  2**si5351_rdiv
   A value of zero gives a divide factor of 1, a value of 7 divides by 128.
   This lightweight method is a reasonable compromise for a seldom used feature.
*/

void si5351bx_init() {                  // Call once at power-up, start PLLA
  uint8_t reg;  uint32_t msxp1;
  Wire.begin();
  i2cWrite(149, 0);                     // SpreadSpectrum off
  i2cWrite(3, si5351bx_clken);          // Disable all CLK output drivers
  i2cWrite(183, ((SI5351BX_XTALPF << 6) | 0x12)); // Set 25mhz crystal load capacitance (tks Daniel KB3MUN)
  msxp1 = 128 * SI5351BX_MSA - 512;     // and msxp2=0, msxp3=1, not fractional
  uint8_t  vals[8] = {0, 1, BB2(msxp1), BB1(msxp1), BB0(msxp1), 0, 0, 0};
  i2cWriten(26, vals, 8);               // Write to 8 PLLA msynth regs
  i2cWrite(177, 0x20);                  // Reset PLLA  (0x80 resets PLLB)
  // for (reg=16; reg<=23; reg++) i2cWrite(reg, 0x80);    // Powerdown CLK's
  // i2cWrite(187, 0);                  // No fannout of clkin, xtal, ms0, ms4
}

void si5351bx_setfreq(uint8_t clknum, uint32_t fout) {  // Set a CLK to fout Hz
  uint32_t  msa, msb, msc, msxp1, msxp2, msxp3p2top;
  if ((fout < 500000) || (fout > 109000000)) // If clock freq out of range
    si5351bx_clken |= 1 << clknum;      //  shut down the clock
  else {
    msa = si5351bx_vcoa / fout;     // Integer part of vco/fout
    msb = si5351bx_vcoa % fout;     // Fractional part of vco/fout
    msc = fout;             // Divide by 2 till fits in reg
    while (msc & 0xfff00000) {
      msb = msb >> 1;
      msc = msc >> 1;
    }
    msxp1 = (128 * msa + 128 * msb / msc - 512) | (((uint32_t)si5351bx_rdiv) << 20);
    msxp2 = 128 * msb - 128 * msb / msc * msc; // msxp3 == msc;
    msxp3p2top = (((msc & 0x0F0000) << 4) | msxp2);     // 2 top nibbles
    uint8_t vals[8] = { BB1(msc), BB0(msc), BB2(msxp1), BB1(msxp1),
                        BB0(msxp1), BB2(msxp3p2top), BB1(msxp2), BB0(msxp2)
                      };
    i2cWriten(42 + (clknum * 8), vals, 8); // Write to 8 msynth regs
    i2cWrite(16 + clknum, 0x0C | si5351bx_drive[clknum]); // use local msynth
    si5351bx_clken &= ~(1 << clknum);   // Clear bit to enable clock
  }
  i2cWrite(3, si5351bx_clken);        // Enable/disable clock
}

void i2cWrite(uint8_t reg, uint8_t val) {   // write reg via i2c
  Wire.beginTransmission(SI5351BX_ADDR);
  Wire.write(reg);
  Wire.write(val);
  Wire.endTransmission();
}

void i2cWriten(uint8_t reg, uint8_t *vals, uint8_t vcnt) {  // write array
  Wire.beginTransmission(SI5351BX_ADDR);
  Wire.write(reg);
  while (vcnt--) Wire.write(*vals++);
  Wire.endTransmission();
}

// *********** End of Jerry's si5315bx routines *********************************************************

/**
   Display Routine
   This display routine prints a line of characters to the upper or lower line of the 16x2 display
   linenmbr = 0 is the upper line
   linenmbr = 1 is the lower line
*/

void printLine(char linenmbr, const char * const c) {
  if (strcmp(c, printBuff[linenmbr])) {     // only refresh the display when there was a change
    lcd.setCursor(0, linenmbr);             // place the cursor at the beginning of the selected line
    lcd.print(c);
    strcpy(printBuff[linenmbr], c);

    for (byte i = strlen(c); i < 16; i++) { // add white spaces until the end of the 16 characters line is reached
      lcd.print(' ');
    }
  }
}

/**
   Building upon the previous routine,
   update Display paints the first line as per current state of the radio
*/

void updateDisplay() {
  // tks Jack Purdum W8TEE
  // replaced fsprint commmands by str commands for code size reduction

  memset(c, 0, sizeof(c));
  memset(b, 0, sizeof(b));

  if (locked || RUNmode == RUN_FINETUNING || RUNmode == RUN_CALIBRATE) {
    ultoa((frequency + fine), b, DEC); // construct the frequency string
    strcpy(c, "");
  }
  else {
    ultoa((frequency + 50), b, DEC); // construct the frequency string
    if (!u.vfoActive)
      strcpy(c, "A ");        // display which VFO is active (A or B)
    else
      strcpy(c, "B ");
  }

  byte p = strlen(b);         // the length of the frequency string (<10 Mhz: 7, >10 MHz: 8)

  strncat(c, &b[0], p - 6);   // display the megahertzes
  strcat(c, ".");
  strncat(c, &b[p - 6], 3);   // display the kilohertzes
  strcat(c, ".");

  if (locked || RUNmode == RUN_FINETUNING || RUNmode == RUN_CALIBRATE)
    strncat(c, &b[p - 3], 3); // display the frequency at 1 Hz precision
  else
    strncat(c, &b[p - 3], 1); // display the frequency at 100 Hz precision

  switch (mode) {             // show the operating mode
    case LSB:
      strcat(c, " LSB");
      break;
    case USB:
      strcat(c, " USB");
      break;
    case CWL:
      strcat(c, " CWL");
      break;
    case CWU:
      strcat(c, " CWU");
      break;
  }

  if (inTx)                   // show the state (TX, SPLIT, or nothing)
    strcat(c, " TX");
  else if (u.splitOn)
    strcat(c, " SP");

  c[16] = '\0';               // cut off any excess characters (string length is max 16 postions)
  printLine(0, c);            // finally print the constructed string to the first line of the display
}

// routine to generate a bleep sound (FB menu)
void bleep(int pitch, int duration, byte repeat) {
  for (byte i = 0; i < repeat; i++) {
    tone(CW_TONE, pitch);
    delay(duration);
    noTone(CW_TONE);
    delay(duration);
  }
}

/**
  Use another transceiver to generate a carrier at a known frequency (for example exactly 7100.000 kHz)
  (or ask a friend to transmit a carrier at a known frequency)
    - first set the VFO to exactly 7100.000 kHz in LSB mode (the received signal may not yet be zero beat at this point)
    - press the Function Button
    - using the tuning pot, adjust the correction value (ppm) for exactly zero beat
    - press the Function Button again to save the setting
    - ask your friend to transmit an LSB signal without changing the frequency
    - using the tuning pot, adjust the BFO frequency for a natural sound in LSB mode
    - press the Function Button again to save the setting
    - the radio will now switch to USB mode. Ask your friend to do the same without changing the frequency.
    - using the tuning pot, adjust the BFO frequency for a natural sound in USB mode
    - press the Function Button again to save the setting
*/

int shift, current_setting;
void calibrate() {
  int knob = analogRead(ANALOG_TUNING); // get the current tuning knob position

  if (firstrun) {
    switch (param) {
      case 1: // VFO fine tuning
        vfo_high = u.vfo_high; // save the original vfo setting
        u.vfo_high = false; // temporarily set the vfo to low side during calibration
        RXshift = 0;
        mode = LSB;
        bfo_freq = u.bfo_freq;
        si5351bx_setfreq(0, u.bfo_freq);
        u.vfoActive = false;   // switch to VFO A
        vfoA = frequency;
        shift = knob;
        printLine(1, "VFO fine tuning");
        break;
      case 2: // calibrate the VFO
        current_setting = u.cal;
        shift = current_setting - knob;
        break;
      case 3: // calibrate BFO for LSB
        current_setting = u.bfo_freq;
        shift = current_setting - BFOFREQ - knob;
        break;
      case 4: // calibrate BFO for CWL
        mode = CWL;
        bfo_freq = u.bfo_freq;
        current_setting = u.bfo_offset_cwl;
        shift = current_setting - knob;
        break;
      case 5: // calibrate BFO for USB
        mode = USB;
        bfo_freq = u.bfo_freq + u.bfo_offset_usb;
        current_setting = u.bfo_offset_usb;
        shift = current_setting - knob;
        break;
      case 6: // calibrate BFO for CWU
        mode = CWU;
        bfo_freq = u.bfo_freq + u.bfo_offset_cwu;
        current_setting = u.bfo_offset_cwu;
        shift = current_setting - knob;
        break;
    }
  }

  switch (param) {
    case 1: // fine tune the VFO
      if (knob < 5)
        shift = shift + 10;
      else if (knob > 1020)
        shift = shift - 10;
      break;
    case 2: // calibrate VFO
      u.cal = constrain(knob + shift, -10000, 10000);
      if (knob < 5 && u.cal > -10000)
        shift = shift - 10;
      else if (knob > 1020 && u.cal < 10000)
        shift = shift + 10;
      break;
    case 3: // calibrate BFO for LSB
      //generate values 11997.5 - 12000.0 kHz from the tuning pot
      bfo_freq = constrain(BFOFREQ + knob + shift, 11997500UL, 12000000UL);
      if (knob < 5 && bfo_freq > 11997500UL)
        shift = shift - 10;
      else if (knob > 1020 && bfo_freq < 12000000UL)
        shift = shift + 10;
      break;
    case 4: // calibrate BFO for CWL
      //generate offset values from the tuning pot (offset relative to BFO setting for LSB)
      u.bfo_offset_cwl = constrain(knob + shift, -750, 0);
      if (knob < 5 && u.bfo_offset_cwl > -750)
        shift = shift - 10;
      else if (knob > 1020 && u.bfo_offset_cwl < 0)
        shift = shift + 10;
      break;
    case 5: // calibrate BFO for USB
      //generate offset values from the tuning pot (offset relative to BFO setting for LSB)
      u.bfo_offset_usb = constrain(knob + shift, -3500, -1250);
      if (knob < 5 && u.bfo_offset_usb > -3500)
        shift = shift - 10;
      else if (knob > 1020 && u.bfo_offset_usb < -1250)
        shift = shift + 10;
      break;
    case 6: // calibrate BFO for CWU
      //generate offset values from the tuning pot (offset relative to BFO setting for LSB)
      u.bfo_offset_cwu = constrain(knob + shift, u.bfo_offset_usb, u.bfo_offset_usb + 750);
      if (knob < 5 && u.bfo_offset_cwu > u.bfo_offset_usb)
        shift = shift - 10;
      else if (knob > 1020 && u.bfo_offset_cwu < u.bfo_offset_usb + 750)
        shift = shift + 10;
      break;
  }

  // if Fbutton is pressed again we save the setting
  if (!digitalRead(FBUTTON)) {
    switch (param) {
      case 1: // fine tune the VFO
        vfoA = frequency;
      case 2: // calibrate VFO
        bleep(600, 50, 1);
        break;
      case 3: // calibrate BFO for LSB
        u.bfo_freq = bfo_freq;
        bleep(600, 50, 1);
        break;
      case 4: // calibrate BFO for CWL
        digitalWrite(CW_CARRIER, 0);     // stop carrier
        noTone(CW_TONE);                 // stop sidetone
        bleep(600, 50, 1);
        break;
      case 5: // calibrate BFO for USB
        bleep(600, 50, 1);
        break;
      case 6: // calibrate BFO for CWU
        digitalWrite(CW_CARRIER, 0);     // stop carrier
        noTone(CW_TONE);                 // stop sidetone
        RUNmode = RUN_NORMAL;
        u.vfo_high = vfo_high;           // restore the original vfo setting
        mode = LSB;
        SetSideBand();
        bleep(600, 50, 2);
        printLine(1, "--- SETTINGS ---");
        shiftBase(); //align the current knob position with the current frequency
        break;
    }
    param ++;
    firstrun = true;
  }

  else {
    RUNmode = RUN_CALIBRATE;
    firstrun = false;
    switch (param) {
      case 1: // fine tune the VFO
        frequency = vfoA - shift + knob;
        setFrequency();
        updateDisplay();
        break;
      case 2: // calibrate VFO
        si5351bx_vcoa = (SI5351BX_XTAL * SI5351BX_MSA) + u.cal * 100L;
        si5351bx_setfreq(2, u.bfo_freq - frequency);
        si5351bx_setfreq(0, u.bfo_freq);
        ltoa(u.cal * 100L / 875, b, DEC);
        strcpy(c, "VFO cal ");
        strcat(c, b);
        strcat(c, " ppm");
        printLine(1, c);
        break;
      case 3: // calibrate BFO for LSB
        break;
      case 4: // calibrate BFO for CWL
        bfo_freq = u.bfo_freq + u.bfo_offset_cwl;
        if (u.cap_sens != 0)
          touch_key();
        if (digitalRead(PTT_SENSE) && (!digitalRead(KEY) || (u.cap_sens != 0 && capaKEY))) {
          digitalWrite(CW_CARRIER, 1);     // start carrier
          tone(CW_TONE, u.CW_OFFSET);      // generate sidetone
        }
        else {
          digitalWrite(CW_CARRIER, 0);     // stop carrier
          noTone(CW_TONE);                 // stop sidetone
        }
        break;
      case 5: // calibrate BFO for USB
        bfo_freq = u.bfo_freq + u.bfo_offset_usb;
        break;
      case 6: // calibrate BFO for CWU
        bfo_freq = u.bfo_freq + u.bfo_offset_cwu;      
        if (u.cap_sens != 0)
          touch_key();
        if (digitalRead(PTT_SENSE) && (!digitalRead(KEY) || (u.cap_sens != 0 && capaKEY))) {
          digitalWrite(CW_CARRIER, 1);     // start carrier
          tone(CW_TONE, u.CW_OFFSET);      // generate sidetone
        }
        else {
          digitalWrite(CW_CARRIER, 0);     // stop carrier
          noTone(CW_TONE);                 // stop sidetone
        }
        break;
    }
    if (param > 2) {
      si5351bx_setfreq(0, bfo_freq);
      setFrequency();
      ultoa(bfo_freq, b, DEC);
      strcpy(c, "BFO ");
      strcat(c, b);
      strcat(c, " Hz");
      printLine(1, c);
    }
  }
}

/**
   The setFrequency is a little tricky routine, it works differently for USB and LSB, depending
   on whether the VFO is set to the low or to the high side of the IF.

   By default the VFO is set to the high side of the IF (vfo_high = true). However this can be
   changed to the low side in the SETTINGS menu.
   Depending on whether the VFO is on the low or on the high side, we need to either add or substract
   the BFO frequency.

   Depending on the mode (LSB,USB) we need to shift the BFO frequency to the correct sideband.

   An additional frequency offset can be added in RX when RIT is enabled.

   Furthermore we add/substract the sidetone frequency only when we receive CW, to assure zero beat
   between the transmitting and receiving station (RXshift)
   The desired sidetone frequency can be set in the SETTINGS menu.
*/

void setFrequency() {
  if (u.vfo_high) {
    if (mode & 1)    // if we are in UPPER side band mode
      si5351bx_setfreq(2, (bfo_freq + frequency - RXshift + RIT + fine));
    else             // if we are in LOWER side band mode
      si5351bx_setfreq(2, (bfo_freq + frequency + RXshift + RIT + fine));
  }
  else {
    if (mode & 1)    // if we are in UPPER side band mode
      si5351bx_setfreq(2, (bfo_freq - frequency + RXshift - RIT - fine));
    else             // if we are in LOWER side band mode
      si5351bx_setfreq(2, (bfo_freq - frequency - RXshift - RIT - fine));
  }
  updateDisplay();
}

/**
   The checkTX toggles the T/R line. If you would like to make use of RIT, etc,
   you must connect pin A0 (black wire) via a 10K resistor to the output of U3
   This is a voltage regulator LM7805 which goes on during TX. We use the +5V output
   as a PTT sense line (to tell the Raduino that we are in TX).
*/

void checkTX() {
  // We don't check for ptt when transmitting cw in semi-QSK mode
  // as long as the TimeOut is non-zero, we will continue to hold the
  // radio in transmit mode
  if (TimeOut > 0 && u.semiQSK)
    return;

  if (digitalRead(PTT_SENSE) && !inTx) {
    // go in transmit mode
    si5351bx_setfreq(2, 0);      // temporarily disable CLK2 to prevent spurious emission (tks Dave M0WID)
    inTx = true;
    RXshift = RIT = RIT_old = 0; // no frequency offset during TX

    if (u.semiQSK) {
      mode = mode & B11111101;   // leave CW mode, return to SSB mode
      SetSideBand();
    }

    delay(TX_DELAY);             // wait till RX-TX burst is over
    shiftBase();                 // this will enable CLK2 again
    updateDisplay();
    if (u.splitOn)               // when SPLIT is on, swap the VFOs
      swapVFOs();
  }

  if (!digitalRead(PTT_SENSE) && inTx) {
    delay(50);
    if (!digitalRead(PTT_SENSE)) {
      //go in receive mode
      inTx = false;
      updateDisplay();
      if (u.splitOn) {             // when SPLIT was on, swap the VFOs back to original state
        swapVFOs();
      }
      if (mode & 2) {              // if we are in CW mode
        RXshift = u.CW_OFFSET;     // apply the frequency offset in RX
        shiftBase();
      }
    }
  }
}

/* CW is generated by unbalancing the mixer when the key is down.
    During key down, the output CW_CARRIER is HIGH (+5V).
   This output is connected via a 10K resistor to the mixer input. The mixer will
   become unbalanced when CW_CARRIER is HIGH, so a carrier will be transmitted.
   During key up, the output CW_CARRIER is LOW (0V). The mixer will remain balanced
   and the carrrier will be suppressed.

   The radio will go into CW mode automatically as soon as the key goes down, and
   return to normal LSB/USB mode when the key has been up for some time.

   There are three variables that track the CW mode
   inTX     : true when the radio is in transmit mode
   keyDown  : true when the CW is keyed down, you maybe in transmit mode (inTX true)
              and yet between dots and dashes and hence keyDown could be true or false
   TimeOut: Figures out how long to wait between dots and dashes before putting
              the radio back in receive mode

   When we transmit CW, we need to apply some offset (800Hz) to the TX frequency, in
   order to keep zero-beat between the transmitting and receiving station. The shift
   depends on whether upper or lower sideband CW is used:
   In CW-U (USB) mode we must shift the TX frequency 800Hz up
   In CW-L (LSB) mode we must shift the TX frequency 800Hz down

   The default offset (CW_OFFSET) is 800Hz, the default timeout (QSK_DELAY) is 350ms.
   The user can change these in the SETTINGS menu.

*/

void checkCW() {
  if (!keyDown && ((u.cap_sens == 0 && !digitalRead(KEY)) || (u.cap_sens != 0 && capaKEY) || (u.key_type > 0 && ((u.cap_sens == 0 && !digitalRead(DAH)) || (u.cap_sens != 0 && capaDAH))))) {
    keyDown = true;

    if (u.semiQSK) {
      mode = mode | 2;                       // if semiQSK is on, switch to CW
      SetSideBand();
    }

    if (u.key_type > 0 && mode & 2) {        // if mode is CW and if keyer is enabled
      keyeron = true;
      released = 0;

      // put the paddles pointers in the correct position
      if (u.key_type & 1) {
        // paddle not reversed
        paddleDAH = &_dah;
        paddleDIT = &_key;
      }
      else {
        // paddle reversed
        paddleDAH = &_key;
        paddleDIT = &_dah;
      }

      if ((u.cap_sens == 0 && !digitalRead(*paddleDIT)) || (u.cap_sens != 0 && capaKEY))
        dit = millis();
      if ((u.cap_sens == 0 && !digitalRead(*paddleDAH)) || (u.cap_sens != 0 && capaDAH))
        dah = millis();
    }

    if (!inTx && u.semiQSK) {          // switch to transmit mode if we are not already in it
      si5351bx_setfreq(2, 0);          // temporarily disable CLK2 to prevent spurious emission (tks Dave M0WID)
      digitalWrite(TX_RX, 1);          // key the PTT - go in transmit mode
      inTx = true;

      if (!u.vfoActive)                // if VFO A is active
        u.mode_A = mode;
      else                             // if VFO B is active
        u.mode_B = mode;

      RXshift = RIT = RIT_old = 0;     // no frequency offset during TX
      delay(TX_DELAY);                 // wait till RX-TX burst is over

      if (u.splitOn)                   // when SPLIT is on, swap the VFOs
        swapVFOs();                    // this will also enable CLK2 again
      else
        shiftBase();                   // this will also enable CLK2 again

      dit = dit + TX_DELAY + 7;        // delay the initial dit
      dah = dah + TX_DELAY + 7;        // delay the initial dah
    }
  }

  //keep resetting the timer as long as the key is down
  if (keyDown)
    TimeOut = millis() + u.QSK_DELAY;

  //if the key goes up again after it's been down
  if (keyDown && ((u.cap_sens == 0 && digitalRead(KEY)) || (u.cap_sens != 0 && !capaKEY))) {
    keyDown = false;
    TimeOut = millis() + u.QSK_DELAY;
  }

  // if we are in semi-QSK mode and have a keyup for a "longish" time (QSK_DELAY value in ms)
  // then go back to RX

  if (!keyeron && TimeOut > 0 && inTx && TimeOut < millis() && u.semiQSK) {

    inTx = false;
    TimeOut = 0;                     // reset the CW timeout counter
    RXshift = u.CW_OFFSET;           // apply the frequency offset in RX
    shiftBase();

    if (u.splitOn)                   // then swap the VFOs back when SPLIT was on
      swapVFOs();

    digitalWrite(TX_RX, 0);          // release the PTT switch - move the radio back to receive
    delay(10);                       //give the relays a few ms to settle the T/R relays
  }

  if (u.key_type == 0 && keyDown && mode & B00000010) {
    digitalWrite(CW_CARRIER, 1);     // generate carrier
    tone(CW_TONE, u.CW_OFFSET);      // generate sidetone
  }
  else if (u.key_type == 0 && digitalRead(SPOT) == HIGH) {
    digitalWrite(CW_CARRIER, 0);     // stop generating the carrier
    noTone(CW_TONE);                 // stop generating the sidetone
  }
}

void keyer() {

  static bool FBpressed = false;
  static bool SPOTpressed = false;

  if (!digitalRead(FBUTTON))         // Press and release F-Button to increase keyer speed
    FBpressed = true;
  if (FBpressed && digitalRead(FBUTTON) && u.wpm < 50) {
    FBpressed = false;
    u.wpm++;
  }
  if (!digitalRead(SPOT))           // Press and release SPOT button to reduce keyer speed
    SPOTpressed = true;
  if (SPOTpressed && digitalRead(SPOT) && u.wpm > 1) {
    SPOTpressed = false;
    u.wpm--;
  }

  if (u.key_type > 2) {             // bug mode
    if ((u.cap_sens == 0 && !digitalRead(*paddleDAH)) || (u.cap_sens != 0 && capaDAH))
      dah = millis();
    else
      dah = 0;
  }

  unsigned long element = 1200UL / u.wpm;

  if (space == 0 && (millis() - dit < element || millis() - dah < 3 * element)) {
    digitalWrite(CW_CARRIER, 1);    // generate carrier
    tone(CW_TONE, u.CW_OFFSET);     // generate sidetone
    keyDown = true;
  }
  else {
    digitalWrite(CW_CARRIER, 0);    // stop generating the carrier
    noTone(CW_TONE);                // stop generating the sidetone
    if (space == 0) {
      space = millis();
    }
    if (millis() - space > gap * element) {
      if (dit < dah) {
        if (ditlatch || (u.cap_sens == 0 && !digitalRead(*paddleDIT)) || (u.cap_sens != 0 && capaKEY)) {
          dit = millis();
          keyeron = true;
          ditlatch = false;
          keyDown = true;
          gap = 1;                  //standard gap between elements
          space = 0;
          released = 0;
        }
        else {
          if (dahlatch || (u.cap_sens == 0 && !digitalRead(*paddleDAH)) || (u.cap_sens != 0 && capaDAH)) {
            dah = millis();
            keyeron = true;
            dahlatch = false;
            keyDown = true;
            gap = 1;                //standard gap between elements
            space = 0;
            released = 0;
          }
          else {
            if (u.autospace)
              gap = 3;              // autospace - character gap is 3 elements
            keyeron = true;
            keyDown = true;

            if (millis() - space > gap * element) {
              keyeron = false;
              keyDown = false;
              gap = 1;              //standard gap between elements
              space = 0;
              released = 0;
            }
          }
        }
      }
      else {
        if (dahlatch || (u.cap_sens == 0 && !digitalRead(*paddleDAH)) || (u.cap_sens != 0 && capaDAH)) {
          dah = millis();
          keyeron = true;
          dahlatch = false;
          keyDown = true;
          gap = 1;                  //standard gap between elements
          space = 0;
          released = 0;
        }
        else {
          if (ditlatch || (u.cap_sens == 0 && !digitalRead(*paddleDIT)) || (u.cap_sens != 0 && capaKEY)) {
            dit = millis();
            keyeron = true;
            ditlatch = false;
            keyDown = true;
            gap = 1;                //standard gap between elements
            space = 0;
            released = 0;
          }
          else {
            if (u.autospace)
              gap = 3;              // autospace - character gap is 3 elements
            keyeron = true;
            keyDown = true;
            if (millis() - space > gap * element) {
              keyeron = false;
              keyDown = false;
              gap = 1;              //standard gap between elements
              space = 0;
              released = 0;
            }
          }
        }
      }
    }
  }

  if (released == 0) {
    if (space == 0 && millis() - dit < element && ((u.cap_sens == 0 && digitalRead(*paddleDIT)) || (u.cap_sens != 0 && !capaKEY)))
      released = millis();
    if (space == 0 && millis() - dah < 3 * element && ((u.cap_sens == 0 && digitalRead(*paddleDAH)) || (u.cap_sens != 0 && !capaDAH)))
      released = millis();
    if (space > 0 && ((u.cap_sens == 0 && digitalRead(*paddleDIT)) || (u.cap_sens != 0 && !capaKEY)) && ((u.cap_sens == 0 && digitalRead(*paddleDAH)) || (u.cap_sens != 0 && !capaDAH)))
      released = millis();
  }

  if (u.cap_sens == 0) {    // if standard paddle is used
    if (released > 0 && millis() - released > DIT_DELAY && !digitalRead(*paddleDIT)) { // DIT_DELAY optimized timing characteristics - tks Hidehiko, JA9MAT
      ditlatch = true;
      dahlatch = false;
    }
    else if (space > 0 && released > 0 && millis() - released > DAH_DELAY && !digitalRead(*paddleDAH)) { // DAH_DELAY optimized timing characteristics - tks Hidehiko, JA9MAT
      dahlatch = true;
      ditlatch = false;
    }
  }
  else {                     // if touch keyer is used
    if (released > 0 && capaKEY) {
      ditlatch = true;
      dahlatch = false;
    }
    else if (released > 0 && capaDAH) {
      dahlatch = true;
      ditlatch = false;
    }
  }

  if (keyeron) {
    itoa(u.wpm, b, DEC);
    strcpy(c, "CW-speed ");
    strcat(c, b);
    strcat(c, " WPM");
    printLine(1, c);
  }
  else if (locked)
    printLine(1, "dial is locked");
  else if (clicks >= 10)
    printLine(1, "--- SETTINGS ---");
  else {
    RIT_old = 0;
    printLine(1, " ");
  }
}


/**
   The Function Button is used for several functions
   NORMAL menu (normal operation):
   1 short press: swap VFO A/B
   2 short presses: toggle RIT on/off
   3 short presses: toggle SPLIT on/off
   4 short presses: toggle mode LSB-USB-CWL-CWU
   5 short presses: start freq scan mode
   5 short presses: start A/B monitor mode
   long press (>1 Sec): VFO A=B
   VERY long press (>3 sec): go to SETTINGS menu

   SETTINGS menu:
   1 short press: Set the 4 scan parameters (lower limit, upper limit, step size, step delay)
   2 short presses: Set the 6 CW parameters (key type, auto-space, touch sensitivity, semi-QSK on/off, QSK delay, sidetone pitch)
   3 short presses: VFO/BFO calibration
   4 short presses: toggle VFO setting (high or low side of IF)
   5 short presses: Set tuning range parameters (minimum dial frequency, max dial freq, tuning pot span)
   6 short presses: enable/disable the PBT function
   long press: exit SETTINGS menu - go back to NORMAL menu
*/

void checkButton() {

  static byte action;
  static long t1, t2;
  static bool pressed = false;

  if (digitalRead(FBUTTON)) {
    t2 = millis() - t1; //time elapsed since last button press
    if (pressed)
      if (clicks < 10 && t2 > 600 && t2 < 3000) { //detect long press to reset the VFO's
        resetVFOs();
        delay(700);
        clicks = 0;
      }

    if (t2 > CLICK_DELAY) { // max time between button clicks (ms)
      action = clicks;
      if (clicks >= 10)
        clicks = 10;
      else
        clicks = 0;
    }
    pressed = false;
  }
  else {
    delay(10);
    if (!digitalRead(FBUTTON)) {
      // button was really pressed, not just some noise

      if (locked && digitalRead(SPOT)) {
        bleep(600, 50, 1);
        printLine(1, MY_CALLSIGN);
        delay(500);
        locked = false;
        shiftBase();
        clicks = 0;
        pressed = false;
        return;
      }

      else {
        if (!digitalRead(SPOT)) {
          bleep(1200, 50, 1);
          locked = true;
          updateDisplay();
          printLine(1, "dial is locked");
          delay(500);
          clicks = 0;
          pressed = false;
          return;
        }
      }

      if (ritOn) {
        toggleRIT(); // disable the RIT when it was on and the FB is pressed again
        old_knob = knob_position();
        bleep(600, 50, 1);
        delay(100);
        return;
      }
      if (!pressed) {
        pressed = true;
        t1 = millis();
        bleep(1200, 50, 1);
        action = 0;
        clicks++;
        if (clicks > 16)
          clicks = 11;
        if (clicks > 6 && clicks < 10)
          clicks = 1;

        switch (clicks) {
          //Normal menu options
          case 1:
            printLine(1, "Swap VFOs");
            break;
          case 2:
            printLine(1, "RIT ON");
            break;
          case 3:
            printLine(1, "SPLIT ON/OFF");
            break;
          case 4:
            printLine(1, "Switch mode");
            break;
          case 5:
            printLine(1, "Start freq scan");
            break;
          case 6:
            printLine(1, "Monitor VFO A/B");
            break;

          //SETTINGS menu options
          case 11:
            printLine(1, "Set scan params");
            break;
          case 12:
            printLine(1, "Set CW params");
            break;
          case 13:
            printLine(1, "VFO/BFO calibr.");
            break;
          case 14:
            printLine(1, "VFO High/Low");
            break;
          case 15:
            printLine(1, "Set tuning range");
            break;
          case 16:
            printLine(1, "PBT ON/OFF");
            break;
        }
      }
      else if ((millis() - t1) > 600 && (millis() - t1) < 800 && clicks < 10) // long press: reset the VFOs
        printLine(1, "Reset VFOs");

      if ((millis() - t1) > 3000 && clicks < 10) { // VERY long press: go to the SETTINGS menu
        bleep(1200, 150, 3);
        printLine(1, "--- SETTINGS ---");
        clicks = 10;
      }

      else if ((millis() - t1) > 1500 && clicks > 10) { // long press: return to the NORMAL menu
        bleep(1200, 150, 3);
        clicks = -1;
        pressed = false;
        printLine(1, " --- NORMAL ---");
        delay(700);
      }
    }
  }
  if (action != 0 && action != 10) {
    bleep(600, 50, 1);
  }
  param = 1;
  switch (action) {
    // NORMAL menu

    case 1: // swap the VFOs
      swapVFOs();
      break;

    case 2: // toggle the RIT on/off
      toggleRIT();
      break;

    case 3: // toggle SPLIT on/off
      toggleSPLIT();
      break;

    case 4: // toggle the mode LSB/USB
      toggleMode();
      break;

    case 5: // start scan mode
      RUNmode = RUN_SCAN;
      TimeOut = millis() + u.scan_step_delay;
      frequency = u.scan_start_freq * 1000L;
      printLine(1, "freq scanning");
      break;

    case 6: // Monitor mode
      RUNmode = RUN_MONITOR;
      TimeOut = millis() + u.scan_step_delay;
      printLine(1, "A/B monitoring");
      break;

    // SETTINGS MENU

    case 11: // set the 4 scan parameters
      scan_params();
      break;

    case 12: // set CW parameters (sidetone pitch, QSKdelay, key type, capacitive touch key, auto space)
      set_CWparams();
      break;

    case 13: // calibrate the VFO and the BFO
      calibrate();
      break;

    case 14: // toggle VFO HIGH/LOW
      u.vfo_high = !u.vfo_high;
      if (u.vfo_high)
        printLine(1, "VFO HIGH");
      else
        printLine(1, "VFO LOW");
      SetSideBand();
      delay(700);
      bleep(600, 50, 2);
      printLine(1, "--- SETTINGS ---");
      break;

    case 15: // set the tuning pot range
      set_tune_range();
      break;

    case 16: // enable/disable PBT
      u.PBT_enabled = !u.PBT_enabled;
      if (u.PBT_enabled)
        printLine(1, "PBT enabled");
      else
        printLine(1, "PBT disabled");
      delay(700);
      bleep(600, 50, 2);
      printLine(1, "--- SETTINGS ---");
      break;
  }
}

void swapVFOs() {
  if (u.vfoActive) {       // if VFO B is active
    u.vfoActive = false;   // switch to VFO A
    vfoB = frequency;
    frequency = vfoA;
    if (!u.splitOn)
      mode = u.mode_A;     // don't change the mode when SPLIT is on
  }

  else {                   //if VFO A is active
    u.vfoActive = true;    // switch to VFO B
    vfoA = frequency;
    frequency = vfoB;
    if (!u.splitOn)
      mode = u.mode_B;     // don't change the mode when SPLIT is on
  }
  SetSideBand();
  if (!inTx && mode > 1)
    RXshift = u.CW_OFFSET; // add RX shift when we are receiving in CW mode
  else
    RXshift = 0;           // no RX shift when we are receiving in SSB mode

  shiftBase();             // align the current knob position with the current frequency
}

void toggleRIT() {

  ritOn = !ritOn;          // toggle RIT
  if (!ritOn)
    RIT = RIT_old = 0;
  shiftBase();             // align the current knob position with the current frequency
  firstrun = true;
  if (u.splitOn) {
    u.splitOn = false;     // disable SPLIT when RIT is on
  }
  updateDisplay();
}

void toggleSPLIT() {

  u.splitOn = !u.splitOn;  // toggle SPLIT
  if (ritOn) {
    ritOn = false;
    RIT = RIT_old = 0;
    shiftBase();
  }
  updateDisplay();
}

void toggleMode() {
  if (!u.semiQSK)
    mode = (mode + 1) & 3; // rotate through LSB-USB-CWL-CWU
  else
    mode = mode xor 1;     // switch between LSB and USB (or between CWL and CWU) (tks Michael, VE3WMB)

  if (mode & 2)            // if we are in CW mode
    RXshift = u.CW_OFFSET;
  else                     // if we are in SSB mode
    RXshift = 0;
  SetSideBand();
}

void SetSideBand() {
  if (u.vfo_high) {
    switch (mode) {
      case USB:
        bfo_freq = u.bfo_freq - PBT_offset;
        break;
      case LSB:
        bfo_freq = u.bfo_freq + u.bfo_offset_usb + PBT_offset;
        break;
      case CWU:
        bfo_freq = u.bfo_freq + u.bfo_offset_cwl - PBT_offset;
        break;
      case CWL:
        bfo_freq = u.bfo_freq + u.bfo_offset_cwu + PBT_offset;
        break;
    }
  }
  else {
    switch (mode) {
      case LSB:
        bfo_freq = u.bfo_freq - PBT_offset;
        break;
      case USB:
        bfo_freq = u.bfo_freq + u.bfo_offset_usb + PBT_offset;
        break;
      case CWL:
        bfo_freq = u.bfo_freq + u.bfo_offset_cwl - PBT_offset;
        break;
      case CWU:
        bfo_freq = u.bfo_freq + u.bfo_offset_cwu + PBT_offset;
        break;
    }
  }
  si5351bx_setfreq(0, bfo_freq);

  setFrequency();
  if (!u.vfoActive)        // if VFO A is active
    u.mode_A = mode;
  else                     // if VFO B is active
    u.mode_B = mode;
}

// resetting the VFO's will set both VFO's to the current frequency and mode
void resetVFOs() {
  printLine(1, "VFO A=B !");
  vfoA = vfoB = frequency;
  u.mode_A = u.mode_B = mode;
  updateDisplay();
  bleep(600, 50, 2);
}

/**
   this routine allows the user to set the tuning range depending on the type of potentiometer
   for a standard 1-turn pot, a span of 50 kHz is recommended
   for a 10-turn pot, a span of 200 kHz is recommended
*/

void set_tune_range() {
  int knob = analogRead(ANALOG_TUNING); // get the current tuning knob position

  if (firstrun) {
    switch (param) {
      case 1:
        current_setting = u.LOWEST_FREQ / 1000;
        break;
      case 2:
        current_setting = u.HIGHEST_FREQ / 1000;
        break;
      case 3:
        current_setting = u.POT_SPAN;
        break;
    }
    shift = current_setting - 10 * knob / 20;
  }
  switch (param) {
    case 1:
      //generate values 7000-7500 from the tuning pot
      u.LOWEST_FREQ = constrain(10 * knob / 20 + shift, 1000UL, 30000UL);
      if (knob < 5 && u.LOWEST_FREQ > 1000UL)
        shift = shift - 10;
      else if (knob > 1020 && u.LOWEST_FREQ < 30000UL)
        shift = shift + 10;
      break;
    case 2:
      //generate values 7000-7500 from the tuning pot
      u.HIGHEST_FREQ = constrain(10 * knob / 20 + shift, (u.LOWEST_FREQ / 1000 + u.POT_SPAN), 30000UL);
      if (knob < 5 && u.HIGHEST_FREQ > (u.LOWEST_FREQ / 1000 + u.POT_SPAN))
        shift = shift - 10;
      else if (knob > 1020 && u.HIGHEST_FREQ < 30000UL)
        shift = shift + 10;
      break;
    case 3:
      //generate values 10-500 from the tuning pot
      u.POT_SPAN = constrain(10 * knob / 20 + shift, 10, 500);
      if (knob < 5 && u.POT_SPAN > 10)
        shift = shift - 10;
      else if (knob > 1020 && u.POT_SPAN < 500)
        shift = shift + 10;
      break;
  }
  // if Fbutton is pressed again, we save the setting
  if (!digitalRead(FBUTTON)) {
    switch (param) {
      case 1:
        u.LOWEST_FREQ = u.LOWEST_FREQ * 1000UL;
        bleep(600, 50, 1);
        delay(200);
        break;
      case 2:
        u.HIGHEST_FREQ = u.HIGHEST_FREQ * 1000UL;
        bleep(600, 50, 1);
        delay(200);
        break;
      case 3:
        RUNmode = RUN_NORMAL;
        bleep(600, 50, 2);
        printLine(1, "--- SETTINGS ---");
        shiftBase(); //align the current knob position with the current frequency
        break;
    }
    param ++;
    firstrun = true;
  }

  else {
    RUNmode = RUN_TUNERANGE;
    firstrun = false;
    switch (param) {
      case 1:
        ultoa(u.LOWEST_FREQ, b, DEC);
        strcpy(c, "min ");
        strcat(c, b);
        strcat(c, " kHz");
        printLine(1, c);
        break;
      case 2:
        ultoa(u.HIGHEST_FREQ, b, DEC);
        strcpy(c, "max ");
        strcat(c, b);
        strcat(c, " kHz");
        printLine(1, c);
        break;
      case 3:
        itoa(u.POT_SPAN, b, DEC);
        strcpy(c, "pot span ");
        strcat(c, b);
        strcat(c, " kHz");
        printLine(1, c);
        break;
    }
  }
}

/**
   this routine allows the user to set the six CW related parameters
*/

void set_CWparams() {
  int knob = analogRead(ANALOG_TUNING); // get the current tuning knob position

  if (firstrun) {
    switch (param) {
      case 1:
        mode = mode | 2; //switch to CW mode
        updateDisplay();
        current_setting = u.key_type;
        shift = knob;
        break;
      case 2:
        current_setting = u.autospace;
        shift = knob;
        break;
      case 3:
        current_setting = u.cap_sens;
        shift = knob;
        break;
      case 4:
        current_setting = u.semiQSK;
        shift = knob;
        break;
      case 5:
        current_setting = u.QSK_DELAY;
        shift = current_setting - 10 * (knob / 10);
        break;
      case 6:
        RXshift = u.CW_OFFSET;
        current_setting = u.CW_OFFSET;
        shift = current_setting - knob - 200;
        break;
    }
  }

  switch (param) {
    case 1:
      //generate values 0-1-2-3-4 from the tuning pot
      u.key_type = ((((knob - shift) + 4 + current_setting * 26) & 127) / 26);
      break;
    case 2:
      //generate values 0-1-0-1 from the tuning pot
      u.autospace = ((((knob - shift + 4) & 64) / 64) + current_setting) & 1;
      break;
    case 3:
      //generate values 0-25 from the tuning pot
      u.cap_sens = constrain((knob - shift) / 40 + current_setting, 0, 25);
      if (knob < 5 && u.cap_sens > 0)
        shift = shift + 10;
      else if (knob > 1020 && u.cap_sens < 25)
        shift = shift - 10;

      //configure the morse keyer inputs
      if (u.cap_sens == 0) { // enable the internal pull-ups if capacitive touch keys are NOT used
        pinMode(KEY, INPUT_PULLUP);
        pinMode(DAH, INPUT_PULLUP);
      }
      else { // disable the internal pull-ups if capacitive touch keys are used
        pinMode(KEY, INPUT);
        pinMode(DAH, INPUT);
      }
      break;
    case 4:
      //generate values 0-1-0-1 from the tuning pot
      u.semiQSK = ((((knob - shift + 4) & 64) / 64) + current_setting) & 1;
      break;
    case 5:
      //generate values 10-1000 from the tuning pot
      u.QSK_DELAY = constrain(10 * (knob / 10) + shift, 10, 1000);
      if (knob < 5 && u.QSK_DELAY >= 20)
        shift = shift - 10;
      else if (knob > 1020 && u.QSK_DELAY < 1000)
        shift = shift + 10;
      break;
    case 6:
      //generate values 500-1000 from the tuning pot
      u.CW_OFFSET = constrain(knob + 200 + shift, 200, 1200);
      if (knob < 5 && u.CW_OFFSET > 200)
        shift = shift - 10;
      else if (knob > 1020 && u.CW_OFFSET < 1200)
        shift = shift + 10;
      break;
  }

  // if Fbutton is pressed again, we save the setting
  if (!digitalRead(FBUTTON)) {
    switch (param) {
      case 1:  // key type
        bleep(600, 50, 1);
        delay(200);
        if (u.key_type == 0) {
          param++;                  // no auto-space when straight key was selected
          if (!CapTouch_installed)
            param++;                // no touch sensitivity setting when touch sensors are not installed
        }
        break;
      case 2:                       // autospace
        bleep(600, 50, 1);
        delay(200);
        if (!CapTouch_installed)
          param++;                  // no touch sensitivity setting when touch sensors are not installed
        break;
      case 3:                       // touch keyer sensitivity
        calibrate_touch_pads();     // measure the base capacitance of the touch pads while they're not being touched
        bleep(600, 50, 1);
        delay(200);
        if (!TXRX_installed)
          param = param + 2;        // no Semi-QSK, QSK-delay settings when RX-TX line is not installed
        break;
      case 4:                       // semiQSK on/off
        if (!u.semiQSK) {
          u.QSK_DELAY = 10;         // set QSKdelay to minimum when manual PTT is selected
          param++;                  // skip the QSKdelay setting when manual PTT is selected
        }
        bleep(600, 50, 1);
        delay(200);
        break;
      case 5:
        bleep(600, 50, 1);
        delay(200);
        break;
      case 6:
        RUNmode = RUN_NORMAL;
        bleep(600, 50, 2);
        printLine(1, "--- SETTINGS ---");
        shiftBase(); //align the current knob position with the current frequency
        break;
    }
    param ++;
    firstrun = true;
  }

  else {
    RUNmode = RUN_CWOFFSET;
    firstrun = false;
    switch (param) {
      case 1:
        strcpy(c, "Key: ");
        switch (u.key_type) {
          case 0:
            strcat(c, "straight");
            break;
          case 1:
            strcat(c, "paddle");
            break;
          case 2:
            strcat(c, "rev. paddle");
            break;
          case 3:
            strcat(c, "bug");
            break;
          case 4:
            strcat(c, "rev. bug");
            break;
        }
        break;
      case 2:
        strcpy(c, "Auto-space: ");
        if (u.autospace)
          strcat(c, "ON");
        else
          strcat(c, "OFF");
        break;
      case 3:
        if (u.cap_sens == 0)
          strcpy(c, "touch keyer OFF");
        else {
          printLine(0, "Touch sensor");
          itoa((u.cap_sens), b, DEC);
          strcpy(c, "sensitivity ");
          strcat(c, b);
        }
        break;
      case 4:
        strcpy(c, "Semi-QSK: ");
        if (u.semiQSK)
          strcat(c, "ON");
        else
          strcat(c, "OFF");
        break;
      case 5:
        itoa(u.QSK_DELAY, b, DEC);
        strcpy(c, "QSK delay ");
        strcat(c, b);
        strcat(c, "ms");
        break;
      case 6:
        itoa(u.CW_OFFSET, b, DEC);
        strcpy(c, "sidetone ");
        strcat(c, b);
        strcat(c, " Hz");
        break;
    }
    printLine(1, c);
  }
}

/**
   this routine allows the user to set the 4 scan parameters: lower limit, upper limit, step size and step delay
*/

void scan_params() {

  int knob = analogRead(ANALOG_TUNING); // get the current tuning knob position
  if (firstrun) {
    switch (param) {

      case 1: // set the lower scan limit

        current_setting = u.scan_start_freq;
        shift = current_setting - knob / 2 - u.LOWEST_FREQ / 1000;
        break;

      case 2: // set the upper scan limit

        current_setting = u.scan_stop_freq;
        shift = current_setting - map(knob, 0, 1024, u.scan_start_freq, u.HIGHEST_FREQ / 1000);
        break;

      case 3: // set the scan step size

        current_setting = u.scan_step_freq;
        shift = current_setting - 50 * (knob / 5);
        break;

      case 4: // set the scan step delay

        current_setting = u.scan_step_delay;
        shift = current_setting - 50 * (knob / 25);
        break;
    }
  }

  switch (param) {

    case 1: // set the lower scan limit

      //generate values 7000-7500 from the tuning pot
      u.scan_start_freq = constrain(knob / 2 + 7000 + shift, u.LOWEST_FREQ / 1000, u.HIGHEST_FREQ / 1000);
      if (knob < 5 && u.scan_start_freq > u.LOWEST_FREQ / 1000)
        shift = shift - 1;
      else if (knob > 1020 && u.scan_start_freq < u.HIGHEST_FREQ / 1000)
        shift = shift + 1;
      break;

    case 2: // set the upper scan limit

      //generate values 7000-7500 from the tuning pot
      u.scan_stop_freq = constrain(map(knob, 0, 1024, u.scan_start_freq, u.HIGHEST_FREQ / 1000) + shift, u.scan_start_freq, u.HIGHEST_FREQ / 1000);
      if (knob < 5 && u.scan_stop_freq > u.scan_start_freq)
        shift = shift - 1;
      else if (knob > 1020 && u.scan_stop_freq < u.HIGHEST_FREQ / 1000)
        shift = shift + 1;
      break;

    case 3: // set the scan step size

      //generate values 50-10000 from the tuning pot
      u.scan_step_freq = constrain(50 * (knob / 5) + shift, 50, 10000);
      if (knob < 5 && u.scan_step_freq > 50)
        shift = shift - 50;
      else if (knob > 1020 && u.scan_step_freq < 10000)
        shift = shift + 50;
      break;

    case 4: // set the scan step delay

      //generate values 0-2500 from the tuning pot
      u.scan_step_delay = constrain(50 * (knob / 25) + shift, 0, 2000);
      if (knob < 5 && u.scan_step_delay > 0)
        shift = shift - 50;
      else if (knob > 1020 && u.scan_step_delay < 2000)
        shift = shift + 50;
      break;
  }

  // if Fbutton is pressed, we save the setting

  if (!digitalRead(FBUTTON)) {
    switch (param) {

      case 1: // save the lower scan limit
      case 2: // save the upper scan limit
      case 3: // save the scan step size
        bleep(600, 50, 1);
        break;

      case 4: // save the scan step delay
        RUNmode = RUN_NORMAL;
        bleep(600, 50, 2);
        printLine(1, "--- SETTINGS ---");
        shiftBase(); //align the current knob position with the current frequency
        break;
    }
    param ++;
    firstrun = true;
  }

  else {
    RUNmode = RUN_SCAN_PARAMS;
    firstrun = false;
    switch (param) {

      case 1: // display the lower scan limit

        itoa(u.scan_start_freq, b, DEC);
        strcpy(c, "lower ");
        strcat(c, b);
        strcat(c, " kHz");
        break;

      case 2: // display the upper scan limit

        itoa(u.scan_stop_freq, b, DEC);
        strcpy(c, "upper ");
        strcat(c, b);
        strcat(c, " kHz");
        break;

      case 3: // display the scan step size

        itoa(u.scan_step_freq, b, DEC);
        strcpy(c, "step ");
        strcat(c, b);
        strcat(c, " Hz");
        break;

      case 4: // display the scan step delay

        itoa(u.scan_step_delay, b, DEC);
        strcpy(c, "delay ");
        strcat(c, b);
        strcat(c, " ms");
        break;
    }
    printLine(1, c);
  }
}

/**
   interrupt service routine
   When the PTT is keyed (either manually or by the semiQSK function), normal program execution
   will be interrupted and the interrupt service routine (ISR) will be executed. After that, normal
   program execution will continue from the point it was interrupted.
   The only thing this ISR does, is setting the TXstart flag. This flag is frequently polled by the
   knob_position routine.
   The knob_position routine takes 100 readings from the tuning pot for extra precision. However
   this takes more time (about 10ms). Normally this is not a problem, however when we key the PTT
   we need to quickly turn off the VFO in order to prevent spurious emission. In that case 10ms is
   too much delay.
   In order to prevent this delay, the knob-position routine keeps checking the TXstart flag
   and when it is set it will terminate immediately.
*/

void ISRptt(void) {
  TXstart = true;                       // the TXstart flag will be set as soon as the PTT is keyed
}

// routine to read the position of the tuning knob at high precision (Allard, PE1NWL)
int knob_position() {
  unsigned long knob = 0;
  // the knob value normally ranges from 0 through 1023 (10 bit ADC)
  // in order to increase the precision by a factor 10, we need 10^2 = 100x oversampling
  for (byte i = 0; i < 100; i++) { // it takes about 10 ms to run this loop 100 times
    if (TXstart) {     // when the PTT was keyed, in order to prevent 10 ms delay:
      TXstart = false; // reset the TXstart flag that was set by the interrupt service routine
      return old_knob; // then exit this routine immediately and return the old knob value
    }
    else
      knob = knob + analogRead(ANALOG_TUNING); // take 100 readings from the ADC
  }
  knob = (knob + 5L) / 10L; // take the average of the 100 readings and multiply the result by 10
  //now the knob value ranges from 0 through 10,230 (10x more precision)
  knob = knob * 10000L / 10230L; // scale the knob range down to 0-10,000
  return (int)knob;
}

/**
   RIT routine
*/

void doRIT() {
  if (millis() - max(dit, dah) < 1000)
    return;
  int knob = knob_position(); // get the current tuning knob position

  if (firstrun) {
    current_setting = RIToffset;
    shift = current_setting - ((knob - 5000) / 2);
    firstrun = false;
  }

  //generate values -2500 ~ +2500 from the tuning pot
  RIToffset = (knob - 5000) / 2 + shift;
  if (knob < 5 && RIToffset > -2500)
    shift = shift - 50;
  else if (knob > 10220 && RIToffset < 2500)
    shift = shift + 50;

  RIT = RIToffset;
  if (RIT != RIT_old) {
    setFrequency();
    itoa(RIToffset, b, DEC);
    strcpy(c, "RIT ");
    strcat(c, b);
    strcat(c, " Hz");
    printLine(1, c);

    RIT_old = RIT;
    old_knob = knob_position();
    delay(30);
  }
}

/**
   routine to align the current knob position with the current frequency
   If we switch between VFO's A and B, the frequency will change but the tuning knob
   is still in the same position. We need to apply some offset so that the new frequency
   corresponds with the current knob position.
   This routine reads the current knob position, then it shifts the baseTune value up or down
   so that the new frequency matches again with the current knob position.
*/

void shiftBase() {
  setFrequency();
  unsigned long knob = knob_position(); // get the current tuning knob position
  baseTune = frequency - (knob * (unsigned long)u.POT_SPAN / 10UL);
}

/**
   The Tuning mechansim of the Raduino works in a very innovative way. It uses a tuning potentiometer.
   The tuning potentiometer that a voltage between 0 and 5 volts at ANALOG_TUNING pin of the control connector.
   This is read as a value between 0 and 1023. By 100x oversampling this range is expanded by a factor 10.
   Hence, the tuning pot gives you 10,000 steps from one end to the other end of its rotation. Each step is 50 Hz,
   thus giving maximum 500 Khz of tuning range. The tuning range is scaled down depending on the POT_SPAN value.
   The standard tuning range (for the standard 1-turn pot) is 50 Khz. But it is also possible to use a 10-turn pot
   to tune accross the entire 40m band. The desired POT_SPAN can be set via the Function Button in the SETTINGS menu.
   When the potentiometer is moved to either end of the range, the frequency starts automatically moving
   up or down in 10 Khz increments, so it is still possible to tune beyond the range set by POT_SPAN.
*/

void doTuning() {
  int knob = analogRead(ANALOG_TUNING) * 100000 / 10230; // get the current tuning knob position

  // tuning is disabled during TX (only when PTT sense line is installed)
  if (inTx && clicks < 10 && abs(knob - old_knob) > 42 && !locked) {
    printLine(1, "dial is locked");
    shiftBase();
    firstrun = true;
    return;
  }
  else if (inTx || locked)            // no tuning in TX or when dial is locked
    return;
  else if (abs(knob - old_knob) < 20)
    save_frequency();                 // only save VFO frequencies to EEPROM when tuning pot is not being turned

  knob = knob_position(); // get the precise tuning knob position
  // the knob is fully on the low end, do fast tune: move down by 10 Khz and wait for 300 msec
  // if the POT_SPAN is very small (less than 25 kHz) then use 1 kHz steps instead

  if (knob == 0 && frequency != u.LOWEST_FREQ) {
    if (frequency > u.LOWEST_FREQ) {
      if (u.POT_SPAN < 25)
        baseTune = baseTune - 1000UL; // fast tune down in 1 kHz steps
      else
        baseTune = baseTune - 10000UL; // fast tune down in 10 kHz steps
      frequency = baseTune + (unsigned long)knob * (unsigned long)u.POT_SPAN / 10UL;
      if (clicks < 10)
        printLine(1, "<<<<<<<"); // tks Paul KC8WBK
      delay(FAST_TUNE_DELAY);
    }
    if (frequency < u.LOWEST_FREQ)
      baseTune = frequency = u.LOWEST_FREQ;
    setFrequency();
    old_knob = 0;
  }

  // the knob is full on the high end, do fast tune: move up by 10 Khz and wait for 300 msec
  // if the POT_SPAN is very small (less than 25 kHz) then use 1 kHz steps instead

  else if (knob == 10000 && frequency != u.HIGHEST_FREQ) {
    if (frequency < u.HIGHEST_FREQ) {
      if (u.POT_SPAN < 25)
        baseTune = baseTune + 1000UL; // fast tune up in 1 kHz steps
      else
        baseTune = baseTune + 10000UL; // fast tune up in 10 kHz steps
      frequency = baseTune + (unsigned long)knob * (unsigned long)u.POT_SPAN / 10UL;
      if (clicks < 10)
        printLine(1, "         >>>>>>>"); // tks Paul KC8WBK
      delay(FAST_TUNE_DELAY);
    }
    if (frequency > u.HIGHEST_FREQ) {
      baseTune = u.HIGHEST_FREQ - (u.POT_SPAN * 1000UL);
      frequency = u.HIGHEST_FREQ;
    }
    setFrequency();
    old_knob = 10000;
  }

  // the tuning knob is at neither extremities, tune the signals as usual
  else {
    if (abs(knob - old_knob) > 4) { // improved "flutter fix": only change frequency when the current knob position is more than 4 steps away from the previous position
      knob = (knob + old_knob) / 2; // tune to the midpoint between current and previous knob reading
      old_knob = knob;
      frequency = constrain(baseTune + (unsigned long)knob * (unsigned long)u.POT_SPAN / 10UL, u.LOWEST_FREQ, u.HIGHEST_FREQ);
      setFrequency();
      delay(10);
    }
  }

  if (!u.vfoActive) // VFO A is active
    vfoA = frequency;
  else
    vfoB = frequency;
}

/**
   "CW SPOT" function: When operating CW it is important that both stations transmit their carriers on the same frequency.
   When the SPOT button is pressed while the radio is in CW mode, the RIT will be turned off and the sidetone will be generated (but no carrier will be transmitted).
   The FINETUNE mode is then also enabled (fine tuning +/- 1000Hz). Fine tune the VFO so that the pitch of the received CW signal is equal to the pitch of the CW Spot tone.
   By aligning the CW Spot tone to match the pitch of an incoming station's signal, you will cause your signal and the other station's signal to be exactly on the same frequency.

   When the SPOT button is pressed while the radio is in SSB mode, the radio will only be put in FINETUNE mode (no sidetone will be generated).
*/

void checkSPOT() {
  if (digitalRead(SPOT) == LOW && !inTx) {
    RUNmode = RUN_FINETUNING;
    TimeOut = millis() - 1000UL;
    if (ritOn) {
      toggleRIT(); // disable the RIT if it was on
      old_knob = knob_position();
    }
  }
}

void finetune() {

  // for SPOT tuning: in CW mode only, generate short side tone pulses every one second
  if ((mode & 2) && millis() - TimeOut > 1000UL) {
    tone(CW_TONE, u.CW_OFFSET);
    if (millis() - TimeOut > 1150UL) {
      noTone(CW_TONE);
      TimeOut = millis();
    }
  }

  int knob = knob_position(); // get the current tuning knob position
  static int fine_old;

  if (digitalRead(SPOT) == LOW && !inTx && !locked) {
    if (firstrun) {
      firstrun = false;
      fine = 0;
      fine_old = 9999;
      shift = (5000 - knob) / 5;
    }

    //generate values -1000 ~ +1000 from the tuning pot
    fine = (knob - 5000) / 5 + shift;
    if (knob < 10 && fine > -1000 && frequency + fine > u.LOWEST_FREQ)
      shift = shift - 10;
    else if (knob > 10220 && fine < 1000 && frequency + fine < u.HIGHEST_FREQ)
      shift = shift + 10;

    if (fine != fine_old) {
      setFrequency();          // apply the finetuning offset
      updateDisplay();
    }

    if (mode & 2)
      printLine(1, "SPOT + FINE TUNE");
    else
      printLine(1, "FINE TUNE");

    fine_old = fine;
  }

  else { // return to normal mode when SPOT button is released
    firstrun = true;
    TimeOut = 0;
    noTone(CW_TONE);
    RUNmode = RUN_NORMAL;
    frequency = frequency + fine; // apply the finetuning offset
    fine = 0;
    shiftBase();
    old_knob = knob_position();
    if (clicks == 10)
      printLine(1, "--- SETTINGS ---");
  }
}

void factory_settings() {

  printLine(0, "loading standard");
  printLine(1, "settings...");

  EEPROM.put(0, u); // save all user parameters to EEPROM
  delay(1000);
}

// routine to save both VFO frequencies when they haven't changed for more than 500Hz in the past 30 seconds

void save_frequency() {
  static unsigned long t3;
  if (abs(vfoA - u.vfoA) > 500UL || abs(vfoB - u.vfoB) > 500UL) {
    if (millis() - t3 > 30000UL) {
      u.vfoA = vfoA;
      u.vfoB = vfoB;
      t3 = millis();
    }
  }
  else
    t3 = millis();
}

void scan() {

  int knob = knob_position();

  if (abs(knob - old_knob) > 8 || digitalRead(PTT_SENSE) || !digitalRead(FBUTTON) || (u.cap_sens == 0 && !digitalRead(KEY)) || (u.cap_sens != 0 && capaKEY) || !digitalRead(SPOT)) {
    //stop scanning
    TimeOut = 0; // reset the timeout counter
    RUNmode = RUN_NORMAL;
    shiftBase();
    delay(400);
  }

  else if (TimeOut < millis()) {
    if (RUNmode == RUN_SCAN) {
      frequency = frequency + u.scan_step_freq; // change frequency
      // test for upper limit of scan
      if (frequency > u.scan_stop_freq * 1000UL)
        frequency = u.scan_start_freq * 1000UL;
      setFrequency();
    }
    else // monitor mode
      swapVFOs();

    TimeOut = millis() + u.scan_step_delay;
  }
}

/**
   Routine to detect whether or not the touch pads are being touched.
   This routine is only executed when the related touch keyer mod is installed.
   We need two 470K resistors connected from the PULSE output to either KEY and DAH inputs.
   We send LOW to the PULSE output and as a result the internal capacitance on the KEY and DAH
   inputs will start to discharge. After a short "threshold" delay, we test whether the
   KEY and DAH inputs are still HIGH or already LOW.
   When the KEY or DAH input is already LOW, it means the internal base capacitance has rapidly
   discharged, so we can conclude the touch pad wasn't touched.
   When the KEY or DAH input is still HIGH, it means that the pad was touched.
   When the pad is touched, the human body adds extra capacitance to the internal base capacity,
   and he increased capacity will not rapidly discharge within the given threshold delay time.
   Finally we send HIGH to the pulse output allowing the capacitance to recharge for the next cycle.
   We can control the touch sensitivity by varying the threshold delay time.
   The minimum delay time is the base_sens value as determined by the calibration routine which
   is executed automatically during power on.
   With minimum delay time we will have maximum touch sensitivity. If we want to reduce the sensitivity
   we add some extra delay time (cap_sens). The user can set the desired touch sensisitivy value in the
   SETTINGS menu (1-25 µs extra delay).
*/

void touch_key() {
  static unsigned long KEYup = 0;
  static unsigned long KEYdown = 0;
  static unsigned long DAHup = 0;
  static unsigned long DAHdown = 0;

  digitalWrite(PULSE, LOW);                            // send LOW to the PULSE output
  delayMicroseconds(base_sens_KEY + 25 - u.cap_sens);  // wait few microseconds for the KEY capacitance to discharge
  if (digitalRead(KEY)) {                              // test if KEY input is still HIGH
    KEYdown = millis();                                // KEY touch pad was touched
    if (!capaKEY && millis() - KEYup > 1) {
      capaKEY = true;
      released = 0;
    }
  }
  else {                                               // KEY touch pad was not touched
    KEYup = millis();
    if (capaKEY && millis() - KEYdown > 10)
      capaKEY = false;
  }

  digitalWrite(PULSE, HIGH);                           // send HIGH to the PULSE output
  delayMicroseconds(50);                               // allow the capacitance to recharge

  digitalWrite(PULSE, LOW);                            // send LOW to the PULSE output
  delayMicroseconds(base_sens_DAH + 25 - u.cap_sens);  // wait few microseconds for the DAH capacitance to discharge

  if (digitalRead(DAH)) {                              // test if DAH input is still HIGH
    DAHdown = millis();                                // DAH touch pad was touched
    if (!capaDAH && millis() - DAHup > 1) {
      capaDAH = true;
      released = 0;
    }
  }
  else {                                               // DAH touch pad was not touched
    DAHup = millis();
    if (capaDAH && millis() - DAHdown > 10)
      capaDAH = false;
  }

  digitalWrite(PULSE, HIGH);                           // send HIGH to the PULSE output
  delayMicroseconds(50);                               // allow the capacitance to recharge

  // put the touch sensors in the correct position
  if (u.key_type == 2 || u.key_type == 4) {
    // swap capaKEY and capaDAH if paddle is reversed
    capaKEY = capaKEY xor capaDAH;
    capaDAH = capaKEY xor capaDAH;
    capaKEY = capaKEY xor capaDAH;
  }
}

/**
   Routine to calibrate the touch key pads
   (measure the time it takes the capacitance to discharge while the touch pads are NOT touched)
   Even when the touch pads are NOT touched, there is some internal capacitance
   The internal capacitance may vary depending on the length and routing of the wiring
   We measure the base capacitance so that we can use it as a baseline reference
   (threshold delay when the pads are not touched).
*/

void calibrate_touch_pads() {
  // disable the internal pullups
  pinMode(KEY, INPUT);
  pinMode(DAH, INPUT);

  bool triggered;
  // first we calibrate the KEY (DIT) touch pad
  base_sens_KEY = 0;                    // base capacity of the KEY (DIT) touch pad
  do {
    base_sens_KEY++;                    // increment the delay time until the KEY touch pad is no longer triggered by the base capacitance
    triggered = false;
    for (int i = 0; i < 100; i++) {
      digitalWrite(PULSE, HIGH);        // bring the KEY input to a digital HIGH level
      delayMicroseconds(50);            // wait a short wile to allow voltage on the KEY input to stabalize
      digitalWrite(PULSE, LOW);         // now bring the KEY input to a digital LOW value
      delayMicroseconds(base_sens_KEY); // wait few microseconds
      if (digitalRead(KEY)) {           // check 100 times if KEY input is still HIGH
        triggered = true;               // if KEY is still high, then it was triggered by the base capacitance
        i = 100;
      }
    }
  } while (triggered && base_sens_KEY != 255);               // keep trying until KEY input is no longer triggered

  // Next we calibrate the DAH pad
  base_sens_DAH = 0;                    // base capacity of the DAH touch pad
  do {
    base_sens_DAH++;                    // increment the delay time until the DAH touch pad is no longer triggered by the base capacitance
    triggered = false;
    for (int i = 0; i < 100; i++) {
      digitalWrite(PULSE, HIGH);        // bring the KEY input to a digital HIGH level
      delayMicroseconds(50);            // wait a short wile to allow voltage on the DAH input to stabalize
      digitalWrite(PULSE, LOW);         // now bring the DAH input to a digital LOW value
      delayMicroseconds(base_sens_DAH); // wait few microseconds
      if (digitalRead(DAH)) {           // check 100 times if DAH input is still HIGH
        triggered = true;               // if KEY is still high, then it was triggered by the base capacitance
        i = 100;
      }
    }
  } while (triggered && base_sens_DAH != 255);                 // keep trying until KEY input is no longer triggered

  if (base_sens_KEY == 255 || base_sens_DAH == 255 || base_sens_KEY == 1 || base_sens_DAH == 1) {   // if inputs are still triggered even with max delay (255 us)
    CapTouch_installed = false;                         // then the base capacitance is too high (or the mod is not installed) so we can't use the touch keyer
    u.cap_sens = 0;                                     // turn capacitive touch keyer OFF
    printLine(0, "touch sensors");
    printLine(1, "not detected");
  }
  else if (u.cap_sens > 0) {
    printLine(0, "touch key calibr");
    strcpy(c, "DIT ");
    itoa(base_sens_KEY, b, DEC);
    strcat(c, b);
    strcat(c, ", DAH ");
    itoa(base_sens_DAH, b, DEC);
    strcat(c, b);
    strcat(c, " us");
    printLine(1, c);
  }
  else
    printLine(1, "touch keyer OFF");

  delay(2000);
  updateDisplay();

  //configure the morse keyer inputs
  if (u.cap_sens == 0) {       // enable the internal pull-ups if touch keyer is disabled
    pinMode(KEY, INPUT_PULLUP);
    pinMode(DAH, INPUT_PULLUP);
  }
}

/**
   This routine is for the PBT control from the frontpanel
   It is only executed when the PBT is enabled from the SETTINGS menu
*/

void PassBandTuning() {
  if (inTx)
    PBT_offset = 0;                                 // no offset during TX (PBT works only in RX)
  else
    PBT_offset = 2 * (analogRead(PBT) - 512); // read the analog voltage from the PBT pot (zero is centre position)
  if (abs(PBT_offset - PBT_offset_old) > 5) {
    SetSideBand();
    PBT_offset_old = PBT_offset;
  }
}

/**
   setup is called on boot up
   It setups up the modes for various pins as inputs or outputs
   initiliaizes the Si5351 and sets various variables to initial state

   Just in case the LCD display doesn't work well, the debug log is dumped on the serial monitor
   Choose Serial Monitor from Arduino IDE's Tools menu to see the Serial.print messages
*/

void setup() {
  u.raduino_version = 204;
  strcpy (c, "Raduino v2.04");

  lcd.begin(16, 2);

  // Start serial and initialize the Si5351
  // Serial.begin(9600);
  analogReference(DEFAULT);

  //configure the function button to use the internal pull-up
  pinMode(FBUTTON, INPUT_PULLUP);

  //configure the SPOT button to use the internal pull-up
  pinMode(SPOT, INPUT_PULLUP);

  pinMode(TX_RX, INPUT_PULLUP);
  if (digitalRead(TX_RX)) { // Test if TX_RX line is installed
    TXRX_installed = false;
    u.semiQSK = false;
    u.QSK_DELAY = 10;
  }

  pinMode(TX_RX, OUTPUT);
  digitalWrite(TX_RX, 0);
  pinMode(CW_CARRIER, OUTPUT);
  digitalWrite(CW_CARRIER, 0);
  pinMode(CW_TONE, OUTPUT);
  digitalWrite(CW_TONE, 0);
  pinMode(PULSE, OUTPUT);
  digitalWrite(PULSE, 0);

  // when Fbutton is kept pressed during power up,
  // or after a version update,
  // then all settings will be restored to the standard "factory" values
  byte old_version;
  EEPROM.get(0, old_version); // previous sketch version
  if (!digitalRead(FBUTTON) || (old_version != u.raduino_version)) {
    factory_settings();
  }

  //configure the PTT SENSE input
  pinMode(PTT_SENSE, INPUT); //disable the internal pull-up

  // attach interrupt to the PTT_SENSE input
  // when PTT_SENSE goes from LOW to HIGH (so when PTT is keyed), execute the ISRptt routine
  attachPCINT(digitalPinToPCINT(PTT_SENSE), ISRptt, RISING);

  printLine(0, c);
  delay(1000);

  //retrieve user settings from EEPROM
  EEPROM.get(0, u);

  calibrate_touch_pads();  // measure the base capacitance of the touch pads while they're not being touched

  //initialize the SI5351
  si5351bx_init();
  si5351bx_vcoa = (SI5351BX_XTAL * SI5351BX_MSA) + u.cal * 100L; // apply the calibration correction factor

  si5351bx_drive[2] = 0;  // VFO drive level (0=2mA, 1=4mA, 2=6mA, 3=8mA)
  si5351bx_drive[0] = 0;  // BFO drive level (0=2mA, 1=4mA, 2=6mA, 3=8mA)

  vfoA = u.vfoA;
  vfoB = u.vfoB;

  if (!u.vfoActive) { // VFO A is active
    frequency = vfoA;
    mode = u.mode_A;
  }
  else { // VFO B is active
    frequency = vfoB;
    mode = u.mode_B;
  }

  if (mode > 1) // if in CW mode
    RXshift = u.CW_OFFSET;

  SetSideBand();

  shiftBase(); //align the current knob position with the current frequency

  //display warning message when VFO calibration data was erased
  if (u.cal == CAL_VALUE) {
    delay (1000);
    printLine(1, "VFO uncalibrated");
    delay(1000);
  }

  bleep(u.CW_OFFSET, 60, 3);
  bleep(u.CW_OFFSET, 180, 1);
}

void loop() {
  switch (RUNmode) {
    case 0: // normal operation
      if (u.cap_sens != 0)
        touch_key();
      if (!inTx && millis() - max(dit, dah) > 1000) {
        checkButton();
        checkSPOT();
        if (clicks == 0 || clicks == 10)
          EEPROM.put(0, u); // save all user parameters to EEPROM
        if (clicks == 0 && !ritOn && !locked)
          printLine(1, MY_CALLSIGN);
      }
      checkCW();
      checkTX();
      if (u.PBT_enabled)
        PassBandTuning();
      if (keyeron)
        keyer();
      if (ritOn && !inTx)
        doRIT();
      else if (millis() - max(dit, dah) > u.QSK_DELAY)
        doTuning();
      return;
    case 1: //calibration
      calibrate();
      break;
    case 2: // set tuning range
      set_tune_range();
      break;
    case 3: // set CW parameters
      set_CWparams();
      if (u.cap_sens != 0)
        touch_key();
      checkCW();
      checkTX();
      if (keyeron)
        keyer();
      return;
    case 4: // scan mode
      scan();
      break;
    case 5: // set scan paramaters
      scan_params();
      break;
    case 6: // A/B monitor mode
      scan();
      break;
    case 7: // Fine tuning mode
      finetune();
      break;
  }
  delay(100);
}