Compiler failed because multiple definition of a function, even is defined as "weak"

Development Libraries
1

Hi all,

I'm trying to build a small software that is using DMA for STM32.
When I'm trying to define HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) the complier is failing with:

..\libraries\SrcWrapper\stm32\uart.c.o: in function `HAL_UART_RxCpltCallback':
uart.c:(.text.HAL_UART_RxCpltCallback+0x0): multiple definition of `HAL_UART_RxCpltCallback'; .. IR_RC_Airwell.ino.cpp:(.text.HAL_UART_RxCpltCallback+0x0): first defined here

This function is defined stm32f4xx_hal_uart.c in stm32core libraries as:

/**
  * @brief  Rx Transfer completed callbacks.
  * @param  huart  Pointer to a UART_HandleTypeDef structure that contains
  *                the configuration information for the specified UART module.
  * @retval None
  */
__weak void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
  /* Prevent unused argument(s) compilation warning */
  UNUSED(huart);
  /* NOTE: This function should not be modified, when the callback is needed,
           the HAL_UART_RxCpltCallback could be implemented in the user file
   */
}

My function is written like this in my IR_RC_Airwell.ino:

..

void setup() {
  // put your setup code here, to run once:
  SerialUSB.begin(1152000);
  SerialUSB.setTimeout(100);
  memset(serUSB, '\0', BUFSIZE);

  HAL_UART_Receive_DMA (&huart1, UART1_rxBuffer, 12);
}

void loop() {

}

void TestFunction(char *buf) {

  /* Prevent unused argument(s) compilation warning */
  //UNUSED(buf);
  /* NOTE: This function should not be modified, when the callback is needed,
           the TestFunction could be implemented in the user file
   */
   SerialUSB.print(buf);
   SerialUSB.print("\n");
}

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {

   SerialUSB.print("OK");
   SerialUSB.print("\n");
    //HAL_UART_Transmit(&huart1, UART1_rxBuffer, 12, 100);
    //HAL_UART_Receive_DMA(&huart1, UART1_rxBuffer, 12);
}

I've repicate a test function in test.cpp and test.h:

#include "test.h"

__weak void TestFunction(char *buf) {

  /* Prevent unused argument(s) compilation warning */
  UNUSED(buf);
  /* NOTE: This function should not be modified, when the callback is needed,
           the TestFunction could be implemented in the user file
   */
}

and my test.h:

#if  defined ( __GNUC__ )
#ifndef __weak
#define __weak   __attribute__((weak))
#endif /* __weak */
#ifndef __packed
#define __packed __attribute__((__packed__))
#endif /* __packed */
#endif /* __GNUC__ */

#define UNUSED(X) (void)X      /* To avoid gcc/g++ warnings */

void TestFunction(char *);

And this function is working without any issues.

What I'm doing wrong?

Kind regards.

2

I'v only seen it with __attribute__((weak))to the RIGHT of the argument list. Maybe try:
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) __weak

3

Indeed the function is defined as weak here

but it's already implemented in uart.c

which seems to be what the compiler is complaining about

4

Hi J-M-L,

Thanks. Now I understand. Seems that is already implemented for Arduino. Now I'm curious if this serial port reading is DMA or not. I have to look in the code.

Thanks!

5

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