spi updates

R/is_rpi_spi.R

@@ -0,0 +1,18 @@
+#' is SPI enabled on this Raspberry Pi?
+#'
+#'
+#' @return TRUE if running on Raspberry Pi and SPI is enabled
+#' @export
+#'
+#' @examplesIf is.rpi()
+#' is.rpi.spi()
+is.rpi.spi <- function() {
+  theReturnValue <- FALSE
+
+  if(is.rpi() 
+     && any(file.exists(Sys.glob("/dev/spi*")))) {
+      theReturnValue <- TRUE
+    }
+
+  return(theReturnValue)
+}

src/other_examples/max7219.c

@@ -0,0 +1,227 @@
+// https://forums.raspberrypi.com/viewtopic.php?t=304828
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <time.h>
+#include <sys/ioctl.h>
+#include <linux/spi/spidev.h>
+
+#define MAX7219_REG_NOOP 0x00
+#define MAX7219_REG_DIGIT0 0x01
+#define MAX7219_REG_DIGIT1 0x02
+#define MAX7219_REG_DIGIT2 0x03
+#define MAX7219_REG_DIGIT3 0x04
+#define MAX7219_REG_DIGIT4 0x05
+#define MAX7219_REG_DIGIT5 0x06
+#define MAX7219_REG_DIGIT6 0x07
+#define MAX7219_REG_DIGIT7 0x08
+#define MAX7219_REG_DECODEMODE 0x09
+#define MAX7219_REG_INTENSITY 0x0A
+#define MAX7219_REG_SCANLIMIT 0x0B
+#define MAX7219_REG_SHUTDOWN 0x0C
+#define MAX7219_REG_DISPLAYTEST 0x0F
+
+#define CMD_WRITE 0x40
+
+typedef struct
+{
+
+ int digits[8];
+
+} max7219;
+
+
+max7219 header;
+
+int spi_fd;
+struct sigaction act;
+static char *spiDevice = "/dev/spidev0.1";
+static uint8_t spiBPW = 8;
+static uint32_t spiSpeed = 5000000;
+static uint16_t spiDelay = 0;
+
+int spiOpen(char* dev)
+{
+  if((spi_fd = open(dev, O_RDWR)) < 0)
+  {
+    printf("error opening %s\n",dev);
+    return -1;
+  }
+  return 0;
+}
+
+void writeByte(uint8_t reg, uint8_t data)
+{
+  uint8_t spiBufTx [3];
+  uint8_t spiBufRx [3];
+  struct spi_ioc_transfer spi;
+  memset (&spi, 0, sizeof(spi));
+  spiBufTx [0] = CMD_WRITE;
+  spiBufTx [1] = reg;
+  spiBufTx [2] = data;
+  spi.tx_buf =(unsigned long)spiBufTx;
+  spi.rx_buf =(unsigned long)spiBufRx;
+  spi.len = 3;
+  spi.delay_usecs = spiDelay;
+  spi.speed_hz = spiSpeed;
+  spi.bits_per_word = spiBPW;
+  ioctl(spi_fd, SPI_IOC_MESSAGE(1), &spi);
+}
+
+void writeBytes(max7219 *header, int cmd, int data)
+{
+  if(!header) return;
+  writeByte(cmd, data);
+}
+
+void setBrightness(max7219 *header, int bright)
+{
+  if(!header) return;
+  if (bright < 0) bright = 0;
+  if (bright > 15) bright = 15;
+
+  writeBytes(header, MAX7219_REG_INTENSITY, bright);
+}
+
+void initialiseDisplay(max7219 *header)
+{
+  spiOpen(spiDevice);
+
+  writeBytes(header, MAX7219_REG_SCANLIMIT, 7);
+  writeBytes(header, MAX7219_REG_DECODEMODE, 0xff);
+  writeBytes(header, MAX7219_REG_SHUTDOWN, 1);
+  writeBytes(header, MAX7219_REG_DISPLAYTEST, 0);
+  setBrightness(header, 5);
+}
+
+void byte_to_binary(int x)
+{
+    static char b[9];
+    b[0] = '\0';
+
+    int z;
+    for (z = 128; z > 0; z >>= 1)
+    {
+        strcat(b, ((x & z) == z) ? "1" : "0");
+    }
+    printf("%s", b);
+}
+
+void digitDisplay(max7219 *header)
+{
+  int i;
+  if(!header) return;
+  for (i=0; i<8; i++)
+  {
+    writeBytes(header, i+1, header->digits[i]);
+  }
+}
+
+void clearDisplay(max7219 *header)
+{
+  int i;
+  if(!header) return;
+  for (i=0; i<8; i++) {
+    header->digits[i] = 0x0F;
+  }
+  digitDisplay(header);
+}
+
+uint8_t asciiToBCD (uint8_t chr)
+{
+  uint8_t bcd_value;
+  bcd_value = (chr - 48);
+  return bcd_value;
+}
+
+void writeDigits(max7219 *header, char chars[12])
+{
+  int i,j;
+  if (!header) return;
+  i = 7;
+  j = 0;
+  while (j <= 11 && i >= 0)
+  {
+    switch ((int)chars[j]) {
+    case '0':
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9':
+
+      header->digits[i] = asciiToBCD(chars[j]);
+      j++;
+      i--;
+      break;
+    case ' ':
+      header->digits[i] = 0x0F;
+      j++;
+      i--;
+      break;
+    case '-':
+      header->digits[i] = 0x0a;
+      j++;
+      i--;
+      break;
+    case ':':
+      header->digits[i] = 0x8f;
+      j++;
+      i--;
+      break;
+    case '.':
+      header->digits[i+1] = header->digits[i+1] + 0x80;
+      j++;
+      break;
+    case 0x00:
+      j = 12;
+      i = -1;
+      break;
+    default:
+      j++;
+      break;
+    }
+  }
+  digitDisplay(header);
+}
+
+void sig_handler(int signum, siginfo_t *info, void *ptr)
+{
+  clearDisplay(&header);
+  printf("Received signal %d\n", signum);
+  printf("Signal originated from process %lu\n",
+    (unsigned long)info->si_pid);
+  exit(0);
+}
+
+int main()
+{
+  memset(&act, 0, sizeof(act));
+
+  act.sa_sigaction = sig_handler;
+  act.sa_flags = SA_SIGINFO;
+  sigaction(SIGTERM, &act, NULL);
+
+  char chars[12] = "12:34:56";
+  initialiseDisplay(&header);
+  clearDisplay(&header);
+
+  while (1)
+  {
+
+    clearDisplay(&header);
+    writeDigits(&header, chars);
+    sleep(1);
+  }
+
+  return 0;
+}