STM32U5 - application with both normal and LPBAM I2C routine with LPDMA and GPDMA

[andrenada]

Hy,

I am trying to implement a code where i am using the I2C3 both in normal mode through the GPDMA and in LPDMA through the linked list.

Switching from the normal mode through the LPBAM linkest list works correctly but then moving back always makes the I2C unusable. 

The main procedure to go back is the following:

    SystemClock_Config();

    HAL_ResumeTick();

    __HAL_RCC_I2C3_CLK_ENABLE();

    __HAL_RCC_GPDMA1_CLK_ENABLE();

    __HAL_RCC_GPIOC_CLK_ENABLE();

    hi2c3.Instance->CR1 &= ~I2C_CR1_PE;

    hi2c3.Instance->AUTOCR = 0;

    HAL_DMA_Abort(&handle_LPDMA1_Channel0);

    HAL_DMAEx_List_UnLinkQ(&handle_LPDMA1_Channel0);

    HAL_DMA_DeInit(&handle_LPDMA1_Channel0);

    hi2c3.State = HAL_I2C_STATE_RESET;

    handle_GPDMA1_Channel0.State = HAL_DMA_STATE_RESET;

    MX_GPDMA1_Init();

    MX_I2C3_Init();

    __HAL_LINKDMA(&hi2c3, hdmarx, handle_GPDMA1_Channel0);

As for the LPBAM i don't have too much experience and I don't understand where the problem could be.

Hope someone has some suggestion on how to fix.

Thanks

[Saket_Om]

Hello @andrenada 

When you say “I2C becomes unusable”, that can mean several different things.

Check which one happens:

• HAL_I2C_Master_Transmit_DMA() returns error immediately
• transfer starts but callback never arrives
• peripheral remains busy
• DMA interrupt never fires
• bus lines are stuck
• NACK/STOP/BERR appears immediately