STM32L4R5AIIx, DCMI and MT9M114 camera chip. DMA does not receive request that there is data in the DCMI data buffer.

[KNguy.5]

I have been working for about 4 weeks on a project which has the STM32L4R5AIIx processor

and is using the camera MT9M114 from ON Semiconductor.

The project uses the following command to take a snap shot.

"HYPERRAM_BASE_ADDRESS" is the starting address of the HYPER-RAM memory.

HAL_DCMI_Start_DMA(&hdcmi, DCMI_MODE_SNAPSHOT, (uint32_t)HYPERRAM_BASE_ADDRESS, DATA_SIZE_WORDS)

When I looked on the scope (I checked the Line Valid line and the Frame Valid line),

I could see that data was coming out of the camera chip.

But in the DCMI Frame Event callback, there was no data in the Hyper-RAM memory.

I know that the Hyper-RAM memory is woeking because I already verified it.

I checked further and found that even though data was coming out of the camera chip,

the DMA never received a request that there was data in the DCMI buffer.

I did this by checking the value of the DMA register "DMA_CNDTRx" in the

DCMI Frame Event callback. The value of this register was not incremented to "0"

Does anyone know why the DMA does not receive a request that there was data in the DCMI buffer?

At the startup of the project I was able to configure the camera successfully through I2C.

Here is the initialization of the DCMI:

// Initialize the DCMI interface

hdcmi.Instance = DCMI;

hdcmi.Init.SynchroMode = DCMI_SYNCHRO_HARDWARE;

hdcmi.Init.PCKPolarity = DCMI_PCKPOLARITY_RISING;

hdcmi.Init.VSPolarity = DCMI_VSPOLARITY_HIGH;

hdcmi.Init.HSPolarity = DCMI_HSPOLARITY_HIGH;

hdcmi.Init.CaptureRate = DCMI_CR_ALL_FRAME;

hdcmi.Init.ExtendedDataMode = DCMI_EXTEND_DATA_8B;

hdcmi.Init.JPEGMode = DCMI_JPEG_DISABLE;

hdcmi.Init.ByteSelectMode = DCMI_BSM_ALL;

hdcmi.Init.ByteSelectStart = DCMI_OEBS_ODD;

hdcmi.Init.LineSelectMode = DCMI_LSM_ALL;

hdcmi.Init.LineSelectStart = DCMI_OELS_ODD;

// Initialize the DMA Channel

hdma_dcmi.Instance = DMA1_Channel1;

hdma_dcmi.Init.Request = DMA_REQUEST_DCMI;

hdma_dcmi.Init.Direction = DMA_PERIPH_TO_MEMORY;

hdma_dcmi.Init.PeriphInc = DMA_PINC_DISABLE;

hdma_dcmi.Init.MemInc = DMA_MINC_ENABLE;

hdma_dcmi.Init.PeriphDataAlignment = DMA_PDATAALIGN_WORD;

hdma_dcmi.Init.MemDataAlignment = DMA_MDATAALIGN_WORD;

hdma_dcmi.Init.Mode = DMA_NORMAL;

hdma_dcmi.Init.Priority = DMA_PRIORITY_HIGH;

if (HAL_DMA_Init(&hdma_dcmi) != HAL_OK)

{

  Error_Handler();

}

__HAL_LINKDMA(hdcmi,DMA_Handle,hdma_dcmi);

HAL_NVIC_SetPriority(DCMI_IRQn, 5, 0);

HAL_NVIC_EnableIRQ(DCMI_IRQn);

/* DMA1_Channel1_IRQn interrupt configuration */

HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, 5, 0);

HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);

/* DMAMUX1_OVR_IRQn interrupt configuration */

HAL_NVIC_SetPriority(DMAMUX1_OVR_IRQn, 5, 0);

HAL_NVIC_EnableIRQ(DMAMUX1_OVR_IRQn);