Issue with BufferedSerial on RP2040 platfrom

ahmedalkabir commented 3 years ago

hey. I faced an issue when using BufferedSerial class specially when writing buffer or data, it just write 2 data and stop ??, actually it is blocking and stuck.

here's the code

#include <Arduino.h>
#include "mbed.h"

rtos::Thread thread_1;
static mbed::BufferedSerial serial_port(p4, p5);

void uart_thread()
{
  serial_port.set_baud(115200);
  serial_port.write("buffer", 7); // never write all of 
  serial_port.write("9", 1);
  char buf[32] = {0};
  while (1)
  {
    if (uint32_t num = serial_port.read(buf, sizeof(buf)))
    {
      serial_port.write(buf, num);
    }
  }
}

void setup()
{
  thread_1.start(uart_thread);
}

I read Serial source code and I noticed it depends on UnbufferedSerial, I tested UnbufferedSerial and it worked as I expected but BufferedSerial's write functionally doesn't work well !

I used PlatformIO and Raspberry Pi Pico which is based on RP2040, so I hope the issue resolve as soon as possible and thanks 😁

magnusnordlander commented 3 years ago

I'm having a similar issue with an Arduino Nano RP2040 Connect; I'm assuming my issue is related.

facchinm commented 3 years ago

Hi there, thanks for reporting the issue! The problem seems to be originated from https://github.com/arduino/mbed-os/blob/d7ccde9f58b366d8653e189ba698c996d4cfa3da/targets/TARGET_RASPBERRYPI/TARGET_RP2040/serial_api.c#L105-L113 . We only provide RX interrupts capability at the moment, so the TX interrupt used by BufferedSerial is not operational.

From the datasheet, it looks like UARTRXINTR and UARTTXINTR can be used to discriminate which event happened, but fixing this would require a not-so-small refactoring. If anyone's interested in taking a look, it would be a wonderful contribution :slightly_smiling_face:

arduino / ArduinoCore-mbed

Issue with BufferedSerial on RP2040 platfrom #272