Help changing default pins and serial

[jimemo]

Hello,
I can get this library working well on Raspberry Pico using default GPIO 0 & 1 to communicate with ESP module.
Now I have another RP2040 device with the ESP module hard wired to pins 8(TX) & 9(RX). Also, from the device's documentation I should be using Serial2. Sample of the code for reference:

  /* Configure pins for communication with ESP32C3-AT */
  Serial2.setTX(8);
  Serial2.setRX(9);
  Serial2.begin(115200);

For the pins I couldn't find anywhere in the code in this library to change the pin numbers.
For the serial I tried changing this line:
#define EspSerial Serial1
To:
#define EspSerial Serial2
It compiled with this error:
undefined reference to _UART2_'

What do I need to put in my code for this device and module to work with ESP_AT_Lib?

[khoih-prog]

I don't have any issue compiling with Serial2

Start from the simplest example UDPClientSingle then moving on from that

Also check Re-assign UART pins? #834 to know that it's OK now to reassign UART to any new pins.

[jimemo]

Thank you for the response @khoih-prog. I reverted to the simpletest example and I received the same error when it attempts to create the firmware.
I am using Platform IO Extension in VSCode to do the compiling. Here is the error using the sampletext code as-is:

Linking .pio\build\pico\firmware.elf
c:/users/jimem/.platformio/packages/toolchain-gccarmnoneeabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld.exe: .pio\build\pico\src\main.cpp.o: in function `_GLOBAL__sub_I__ZN7ESP8266C2EPN7arduino6StreamE':
main.cpp:(.text.startup._GLOBAL__sub_I__ZN7ESP8266C2EPN7arduino6StreamE+0x14): undefined reference to `_UART2_'
c:/users/jimem/.platformio/packages/toolchain-gccarmnoneeabi/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld.exe: .pio\build\pico\src\main.cpp.o: in function `setup':
main.cpp:(.text.setup+0x124): undefined reference to `_UART2_'
collect2.exe: error: ld returned 1 exit status
*** [.pio\build\pico\firmware.elf] Error 1

I get these additional errors during compiling but only when I attempt to reassign the pins, e.g. EspSerial.setRX(9);

In file included from .pio\libdeps\pico\ESP_AT_Lib\src/ESP_AT_Lib.h:67,
                 from src\main.cpp:11:
C:\Users\jimem\.platformio\packages\framework-arduino-mbed\cores\arduino/Arduino.h:111:17: error: '_UART2_' does not name a type
  111 | #define Serial2 _UART2_
      |                 ^~~~~~~

[khoih-prog]

C:\Users\jimem.platformio\packages\framework-arduino-mbed\cores\arduino/Arduino.h:111:17: error: 'UART2' does not name a type
111 | #define Serial2 UART2

The mbed_rp2040 core doesn't support Serial2 without modification.

Check https://github.com/arduino/ArduinoCore-mbed/blob/master/variants/RASPBERRY_PI_PICO/pins_arduino.h#L40-L86

// Serial
#define PIN_SERIAL_TX (0ul)
#define PIN_SERIAL_RX (1ul)

...

#define SERIAL_HOWMANY		1
#define SERIAL1_TX			(digitalPinToPinName(PIN_SERIAL_TX))
#define SERIAL1_RX			(digitalPinToPinName(PIN_SERIAL_RX))

#define SERIAL_PORT_USBVIRTUAL      SerialUSB
#define SERIAL_PORT_MONITOR         SerialUSB
#define SERIAL_PORT_HARDWARE        Serial1
#define SERIAL_PORT_HARDWARE_OPEN   Serial1

You have to use arduino-pico core.

Check Great job! Do you have a plan to adjust it for Platformio? #66 for more info how to convert to use PIO.

If not absolutely necessary, I suggest you use Arduino IDE if still have problem with PIO.

[jimemo]

Thanks @khoih-prog for the advice.

I didn't want to modify the mbed_rp2040 core code but it's useful to know that's where those settings live.

I tried with the alternative arduino-pico core but I couldn't get my existing code to compile properly due to incompatibile
libraries. I have another project in mind with the Pico W board and arduino-pico core looks like good for that though!

Eventually I came across a solution here https://forum.arduino.cc/t/serial2-on-raspberry-pi-pico/875244/3
What worked for me:
In UDPClientSingle
After setting Serial2
#define EspSerial Serial2
Add a new line (tx,rx,0,0)
UART EspSerial(8, 9, 0, 0);
Before
ESP8266 wifi(&EspSerial);