use both I2C Master DMA and UART DMA at once

[Frogram]

Hi all,

I am trying to use I2C DMA as Master and UART DMA

My code is

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim){
  if (c == 1)  {
	  HAL_UART_Transmit_DMA(&huart2, (uint8_t *)b, 8);
  } else {
	  /* I2C Transmit code */
  }
  c = 1 - c;
}

and which I tried are (instead of /* I2C Transmit code */) :

// 1. polling, it worked
	  HAL_I2C_Master_Transmit(~~, 50);
	  HAL_I2C_Master_Receive(~~, 50);
// 2. DMA, not worked
          HAL_I2C_Master_Transmit_DMA(~~);
          HAL_I2C_Master_Receive_DMA(~~);
// 3. Mem read dma, not worked
	  HAL_I2C_Mem_Read_DMA(~~);
// 4. Seq DMA, not worked
	  HAL_I2C_Master_Seq_Transmit_DMA(~~, I2C_FIRST_FRAME);
	  HAL_I2C_Master_Seq_Receive_DMA(~~, I2C_LAST_FRAME);

I have no Idea whats wrong and how to solve it

thanks

[Amel NASRI]

Hi @Frogram​ ,

1. Does Uart DMA work properly?
2. Is your initialization code generated with STM32CubeMX? If you are using latest STM32CubeMX version 6.3.0, please make sure to have correct order for HAL_DMA_Init() and peripheral init.

-Amel

[Frogram]

Hi

1. yes, UART DMA works well
2. I used STM32CubeIDE for create .ioc and here is no HAL_DMA_Init() only MX_DMA_Init(). how could I add it?

[Amel NASRI]

Yes it is MX_DMA_Init().

Please make sure that it is called after MX_I2C_Init().

-Amel

[Frogram]

The code was already set as you said. TT

[Amel NASRI]

I wanted to discard the fact that root cause of your issue is generated initialization code by STM32CubeMX.

Now it should be better to try to run I2C in DMA mode as a standalone application.

If it is working, then check interrupts priority.

-Amel

[Frogram]

how should I set priority? one of them as higher?

[Amel NASRI]

I2C is time-sensitive. It is recommended to set higher priority for its interrupts.

-Amel

[Amel NASRI]

Hi @Frogram​ ,

Sorry, what I said in my previous comment is wrong:

Yes it is MX_DMA_Init().

Please make sure that it is called after MX_I2C_Init().

In fact, I2C initialization modifies some DMA register and needs its clock to be activated (here an explanation provided by TDK).

That is why it is required to call MX_DMA_Init() first then MX_I2C_Init(). STM32Cub eMX has to do this for you, but it is a regression in 6.3.0 version.

-Amel