OV7670 and DCMI problem

Posted on July 27, 2014 at 05:18

I have been trying to get the OV7670 cam working with STM32F207zg but seems like something is not clear , first i need to know what is the buffer size to set the DMA to when i want to transfer a snapshot from the cam to External SRAM (since i can not directly send it to the LCD) , say i want 240 * 320 pixels  (RGB565) , and the external RAM is 16-bit wide , so what should be the buffer size for the DMA ? ........

also im not sure if the documentation is clear about the VSYNC and HSYNC , the camera module has the VSYNC active high (i,e Data r not sampled when its high) and HSYNC active low , so what should the DCMI settings for VSYNC and HSYNC ?

with the following code , i get DMA FIFO ERROR , and I get the frame flag set , but when i display the frame (even if not complete) , the LCD shows noise

    DMA_InitTypeDef DMA_DCMI;

    // Configure the DCMI

    // Enable the Clck of the DCMI module

    RCC_AHB2PeriphClockCmd (RCC_AHB2Periph_DCMI , ENABLE);

    // Reset the DCMI Registers

RCC_AHB2PeriphResetCmd(RCC_AHB2Periph_DCMI, ENABLE);

   RCC_AHB2PeriphResetCmd(RCC_AHB2Periph_DCMI, DISABLE);

    //

    // Configure the DCMI

    DCMI_Struct.DCMI_CaptureMode=DCMI_CaptureMode_SnapShot;

    DCMI_Struct.DCMI_CaptureRate=DCMI_CaptureRate_All_Frame;

    DCMI_Struct.DCMI_ExtendedDataMode=DCMI_ExtendedDataMode_8b;

    DCMI_Struct.DCMI_HSPolarity=DCMI_HSPolarity_Low;

    DCMI_Struct.DCMI_PCKPolarity=DCMI_PCKPolarity_Rising;

    DCMI_Struct.DCMI_VSPolarity=DCMI_VSPolarity_High;

    DCMI_Struct.DCMI_SynchroMode=DCMI_SynchroMode_Hardware;

    DCMI_Init(&DCMI_Struct);

    //

    // Enable the NVIC for the DCMI

    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

    NVIC_DCMI.NVIC_IRQChannel=DCMI_IRQn;

    NVIC_DCMI.NVIC_IRQChannelCmd=ENABLE;

    NVIC_DCMI.NVIC_IRQChannelPreemptionPriority=1;

    NVIC_DCMI.NVIC_IRQChannelSubPriority=2;

    NVIC_Init(&NVIC_DCMI);

    //

    //

    NVIC_DCMI.NVIC_IRQChannel=DMA2_Stream1_IRQn;

    NVIC_DCMI.NVIC_IRQChannelCmd=ENABLE;

    NVIC_DCMI.NVIC_IRQChannelPreemptionPriority=1;

    NVIC_DCMI.NVIC_IRQChannelSubPriority=1;

    NVIC_Init(&NVIC_DCMI);

    

    //

    // Enable the DCMI Interrupts

    DCMI_ITConfig(DCMI_IT_VSYNC, ENABLE);

 DCMI_ITConfig(DCMI_IT_LINE, ENABLE);

  DCMI_ITConfig(DCMI_IT_FRAME, ENABLE);

//  DCMI_ITConfig(DCMI_IT_ERR, ENABLE);    //

//    //

    // Enable DMA2 Clock

     RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);  

    // Configure the DMA

     DMA_DCMI.DMA_Channel = DMA_Channel_1;  

  DMA_DCMI.DMA_PeripheralBaseAddr = DCMI_DR_ADDRESS;    

  DMA_DCMI.DMA_Memory0BaseAddr = 0x64000000;

  DMA_DCMI.DMA_DIR = DMA_DIR_PeripheralToMemory;

  DMA_DCMI.DMA_BufferSize = 320*240*2;

  DMA_DCMI.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

  DMA_DCMI.DMA_MemoryInc = DMA_MemoryInc_Enable;

  DMA_DCMI.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;

  DMA_DCMI.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

  DMA_DCMI.DMA_Mode = DMA_Mode_Normal;

  DMA_DCMI.DMA_Priority = DMA_Priority_High;

  DMA_DCMI.DMA_FIFOMode = DMA_FIFOMode_Enable;         

  DMA_DCMI.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;

  DMA_DCMI.DMA_MemoryBurst = DMA_MemoryBurst_Single;

  DMA_DCMI.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;

    DMA_Init(DMA2_Stream1, &DMA_DCMI);

    DMA_ITConfig(DMA2_Stream1 , DMA_IT_TC , ENABLE);

    DMA_ITConfig(DMA2_Stream1 , DMA_IT_FE  , ENABLE);

// Enable the Capture mode

      DMA_Cmd(DMA2_Stream1, ENABLE);

    /* Enable DCMI interface */

    DCMI_Cmd(ENABLE);

    /* Start Image capture */

    DCMI_CaptureCmd(ENABLE);

    //

//

//

.

.

.

void DCMI_IRQHandler()

{

    

if (DCMI_GetITStatus(DCMI_IT_VSYNC) != RESET)

    {                    

        DCMI_ClearITPendingBit(DCMI_IT_VSYNC);

    }

    

    if (DCMI_GetITStatus(DCMI_IT_LINE) != RESET)

    {

        DCMI_ClearITPendingBit(DCMI_IT_LINE);      

    }

    

    if (DCMI_GetITStatus(DCMI_IT_FRAME) != RESET)

    {

        DCMI_ClearITPendingBit(DCMI_IT_FRAME);

        for(count=0; count<76800 ; count++)

        {

        LCD_REG=0x22;

        LCD_RAM=BUFF[count];

        }

    }

    if (DCMI_GetITStatus(DCMI_IT_ERR) != RESET)

    {

        DCMI_ClearITPendingBit(DCMI_IT_ERR);

    }

}

..

..

Any ideas? ...... Is it cam settings , is it the DCMI ? >>>>>> thx in advance .