Solved
STM32G4 RX DMA not working
- I have a Nucleo board https://www.st.com/en/evaluation-tools/nucleo-g491re.html
- I have configured USART1 on PC4 and PC5 in STM32CubeMX, with interrupts and RX DMA
- I can send but not receive
- I was able to get it working on a discovery board before with the same code, but different processor: https://www.st.com/en/evaluation-tools/32l152cdiscovery.html
I tested the sending with a USB-serial converter and I can see the MCU is sending. Looping back the TX signal to the RX on the board doesn't result in receiving data, nor does connecting the TX of the USB-serial converter. However I do get RX line error interrupts if I connect the wire, and if I enable idle line interrupt that works too.
Here is my stripped down code:
#include "app_main.h"
#include "main.h" // includes correct STM32 HAL
//RTOS includes
#include "FreeRTOS.h"
#include "task.h"
#include "cmsis_os2.h"
#include <stdio.h>
#include <sys/unistd.h>
#ifdef DEBUG
extern "C" int _write(int file, char* data, int size)
{
if ((file != STDOUT_FILENO) && (file != STDERR_FILENO))
{
return -1;
}
for(int i = 0; i < size; ++i)
{
ITM_SendChar(data[i]);
}
return size;
}
#endif
static TaskHandle_t appMainTaskHandle;
static constexpr UBaseType_t APP_MAIN_TASK_PRIORITY = ( UBaseType_t ) (osPriorityNormal) ;
static constexpr size_t APP_MAIN_TASK_STACK_SIZE_BYTES = 2048;
extern UART_HandleTypeDef huart1;
/*
USART1:
PC4 TX
PC5 RX
*/
static void uartTestTask(void* arg)
{
constexpr size_t m_BUFFER_SIZE = 50;
uint8_t m_rxBuffer[m_BUFFER_SIZE];
const uint8_t* m_rxTail;
UART_HandleTypeDef* const m_pUartHandle = &huart1;
m_rxTail = m_rxBuffer; // reset buffer
HAL_UART_Receive_DMA(m_pUartHandle, (uint8_t*)m_rxBuffer, m_BUFFER_SIZE); // start DMA reception
while(1)
{
size_t len;
const uint8_t* rxHead = m_rxBuffer + m_BUFFER_SIZE - m_pUartHandle->hdmarx->Instance->CNDTR;
if (rxHead >= m_rxTail)
{
len = rxHead - m_rxTail;
}
else
{
len = rxHead - m_rxTail + m_BUFFER_SIZE;
}
printf("len: %d\n", len);
HAL_UART_Transmit(m_pUartHandle, (uint8_t*)"test\n", 5, 1000);
vTaskDelay(1000 / portTICK_PERIOD_MS); //startup delay
}
}
static void appMainTask(void* arg)
{
vTaskDelay(10 / portTICK_PERIOD_MS); //startup delay
[[maybe_unused]] BaseType_t res =
xTaskCreate(
uartTestTask,
"uartTestTask",
APP_MAIN_TASK_STACK_SIZE_BYTES/4,
NULL,
APP_MAIN_TASK_PRIORITY,
NULL );
while(1)
{
vTaskDelay(1000 / portTICK_PERIOD_MS);
}
}
extern "C" bool startAppMainTask()
{
BaseType_t res = xTaskCreate( appMainTask,
"appMain",
APP_MAIN_TASK_STACK_SIZE_BYTES/4,
NULL,
APP_MAIN_TASK_PRIORITY,
&appMainTaskHandle );
return res == pdPASS;
}