DCMI camera interface program with DMA with STM32f4-discovery board

[theparitt]

Posted on July 23, 2012 at 02:15

Hi,

I am now trying to integrate my STM32Discovery board with OV7670 camera module without using any external ram from LCD. However I found a problem and I cannot get any data. I have tested it in many ways from counting the number of HCLK line per VSYNC to see the camera-output signal from my oscilloscope. I found the problem that everytime I enable camera-capture ( DCMI_CaptureCmd(Enable) ) It always generate overflow interrupt ( DCMI_GetFlagStatus(DCMI_FLAG_OVFRI) == SET). I suspect that my DMA procedure is incorrect. Could someone help me to trace my code to find errors? Note: I set my OV7670 output resolution to 320x240 QVGA. First i declare memory to store the data from camera

int8_t frame_buffer[320*240]; //store frame data in here

Here is the code that I initialize my GPIO and also enable interrupt for debugging purpose..

int8_t frame_buffer[320*240];
EXTI_InitTypeDef EXTI_InitStructure;
void DCMI_GPIO_Configure()
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA | RCC_AHB1Periph_GPIOB
| RCC_AHB1Periph_GPIOC | RCC_AHB1Periph_GPIOE, ENABLE);
/* B7: VSYNC*/
GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_DCMI);
/* A4: HSYNC*/
GPIO_PinAFConfig(GPIOA, GPIO_PinSource4, GPIO_AF_DCMI);
/* A6: PCLK*/
GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_DCMI);
/* C6: data0*/
GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_DCMI);
/* C7: data1*/
GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_DCMI);
/* E0: data2*/
GPIO_PinAFConfig(GPIOE, GPIO_PinSource0, GPIO_AF_DCMI);
/* E1: data3*/
GPIO_PinAFConfig(GPIOE, GPIO_PinSource1, GPIO_AF_DCMI);
/* E4: data4*/
GPIO_PinAFConfig(GPIOE, GPIO_PinSource4, GPIO_AF_DCMI);
/* B6: data5*/
GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_DCMI);
/* E5: data6*/
GPIO_PinAFConfig(GPIOE, GPIO_PinSource5, GPIO_AF_DCMI);
/* E6: data7*/
GPIO_PinAFConfig(GPIOE, GPIO_PinSource6, GPIO_AF_DCMI);
/* DCMI GPIO configuration */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 | GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1
| GPIO_Pin_4 | GPIO_Pin_5 | GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOE, &GPIO_InitStructure);
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = DMA2_Stream1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
NVIC_InitStructure.NVIC_IRQChannel = DCMI_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}

Here is my DCMI configuration part.

void DCMI_Configure(void)
{
DCMI_InitTypeDef DCMI_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
/*** Configures the DCMI to interface with the OV2640 camera module ***/
/* Enable DCMI clock */
RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_DCMI, ENABLE);
/* DCMI configuration */
//bit[14]: DCMI_Enable
//bit[13:12]: reserved
DCMI_InitStructure.DCMI_ExtendedDataMode = DCMI_ExtendedDataMode_8b; //bit[11:10]: 8bit-data/pclk
DCMI_InitStructure.DCMI_CaptureRate = DCMI_CaptureRate_1of4_Frame; //bit[9:8]: Frame Capture Rate Control
DCMI_InitStructure.DCMI_VSPolarity = DCMI_VSPolarity_High; //LOW?HIGH? //bit[7]: VSYNC active @low
DCMI_InitStructure.DCMI_HSPolarity = DCMI_HSPolarity_High; //bit[6]: HSYNC active @high
DCMI_InitStructure.DCMI_PCKPolarity = DCMI_PCKPolarity_Rising; //bit[5]: PCLK at Rising Edge
DCMI_InitStructure.DCMI_SynchroMode = DCMI_SynchroMode_Hardware; //bit[4]: use hardware VSYNC/HSYNC
//DCMI_JPEGCmd(ENABLE/DISABLE) bit[3]: JPEG Mode
//bit[2]: Crop mode
DCMI_InitStructure.DCMI_CaptureMode = DCMI_CaptureMode_Continuous; //bit[1]: capture mode 0:continue(หลังจา�? Capture�?ล้ว CaptureCmd ยัง Enable) 1:snapshot
//bit[0]: capture 0:disable/1:enable
//ตั้งค่าทั้งหมดให้ DCMI
DCMI_Init(&DCMI_InitStructure);
//----- mask interrupt for DCMI -----
DCMI_ITConfig(DCMI_IT_VSYNC, ENABLE);
DCMI_ITConfig(DCMI_IT_LINE, ENABLE);
DCMI_ITConfig(DCMI_IT_FRAME, ENABLE);
DCMI_ITConfig(DCMI_IT_OVF, ENABLE);
DCMI_ITConfig(DCMI_IT_ERR, ENABLE);
/* Configures the DMA2 to transfer Data from DCMI */
/* Enable DMA2 clock */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);
/* DMA2 Stream1 Configuration */
DMA_DeInit(DMA2_Stream1);
DMA_StructInit(&DMA_InitStructure);
DMA_InitStructure.DMA_Channel = DMA_Channel_1;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(DCMI_BASE + 0x28);
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&frame_buffer[0];
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = 0xFFFF;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
/* DMA2 IRQ channel Configuration */
DMA_Init(DMA2_Stream1, &DMA_InitStructure);
}

and Here is my main.c

void main()
{ 
......
DCMI_GPIO_Configure()
DCMI_Configure(void)
.....
DMA_Cmd(DMA2_Stream1, ENABLE);
DCMI_Cmd(ENABLE);
DCMI_CaptureCmd(ENABLE);
int z = 0;
while(1);
}

and this is the way I debug my code using interrupt .

int count = 0;
int start = 0;
void DCMI_IRQHandler(void)
{
if(DCMI_GetFlagStatus(DCMI_FLAG_VSYNCRI) == SET)
{
if(start == 0)
{
start = 1;
}
else
{
start = 0;
}
}
else if(DCMI_GetFlagStatus(DCMI_FLAG_LINERI) == SET)
{
if(start == 1)
{
count++;
}
else
{
if(count != 0)
{
//printf(''count: %d \n\n'', count); //just dor counting the number of line
}
count = 0;
}
}
else if(DCMI_GetFlagStatus(DCMI_FLAG_FRAMERI) == SET)
{
printf(''DCMI_FLAG_FRAMERI \n\n'');
}
else if(DCMI_GetFlagStatus(DCMI_FLAG_ERRRI) == SET)
{
printf(''DCMI_FLAG_ERRRI \n\n'');
}
else if(DCMI_GetFlagStatus(DCMI_FLAG_OVFRI) == SET)
{
printf(''DCMI_FLAG_OVFRI \n\n''); //********** Unfortunately.. my code always comes here
}
DCMI_ClearFlag(DCMI_FLAG_VSYNCRI);
DCMI_ClearFlag(DCMI_FLAG_LINERI);
DCMI_ClearFlag(DCMI_FLAG_FRAMERI);
DCMI_ClearFlag(DCMI_FLAG_ERRRI);
DCMI_ClearFlag(DCMI_FLAG_OVFRI);
}

So my first thought is DMA error. I am not sure how to fix it. Everything seems correct. The reason that I don't want to use LCD and connect as external ram because I would like to only save the data to SD card and make my system as small as possible. I don't need to display an image to a user. :) #ask-smarter-questions #dcmi-dma-stm32f4-sicovery-camera

[Tesla DeLorean]

Posted on July 23, 2012 at 02:50

I think I'd start by correctly defining the size of the circular DMA, the way it works at the moment it's going to blow away a 128KB swath. Likely trashing things you'd rather it didn't.

[theparitt]

Posted on July 23, 2012 at 04:20

Hi clive1  

      Thanks for your reply. Could you explain a bit more about the problem with the circular DMA? Should I set it back to normal mode or change the size of my buffer.Thanks

[theparitt]

Posted on July 23, 2012 at 13:40 Hi clive1, I changed my DMA code to;

/* Configures the DMA2 to transfer Data from DCMI */
/* Enable DMA2 clock */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);
/* DMA2 Stream1 Configuration */
DMA_DeInit(DMA2_Stream1);
DMA_StructInit(&DMA_InitStructure);
DMA_InitStructure.DMA_Channel = DMA_Channel_1;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(DCMI_BASE);
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&frame_buffer[0];
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = 320 * 240; /********* CHANGE *************/
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; /*********** CHANGE **********/
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
/* DMA2 IRQ channel Configuration */
DMA_Init(DMA2_Stream1, &DMA_InitStructure);

I have the same error as before.. DCMI overflow... Could anyone suggest me what the problem is? Thank a lot

[theparitt]

Posted on July 23, 2012 at 14:26

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
I change this to Byte size but it's still doesnt work.
I am not sure about the ''DMA_PeripheralInc'' , ''DMA_MemoryInc'' and ''DMA_MemoryBurst''
The document from STM32 is not that clear.
Thanks

[Tesla DeLorean]

Posted on July 23, 2012 at 14:28

Surely for half word (16-bit) transfers
 DMA_InitStructure.DMA_BufferSize = 320 * 240 / 2;

Not that this is causing you other issues, just compound them. Doing it as bytes won't help, as the transfer count is limited to 65535

[theparitt]

Posted on July 23, 2012 at 15:07

I see. Thanks for point it out.  How can I transfer data larger than 0xFFFF. ?   

since my data is 320 * 240 = 76800 which is larger than the limitation of DMA.Thanks 

[theparitt]

Posted on July 23, 2012 at 16:34

Now I change my code 

 DMA_InitStructure.DMA_BufferSize = 1;   <------------------- ONLY one byte transferIt's still overflow in DCMI interrupt.I have no idea why the interrupt is set.Thanks

[Tesla DeLorean]

Posted on July 23, 2012 at 17:17

since my data is 320 * 240 = 76800 which is larger than the limitation of DMA.

 DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

Which is 38400 half-words (16-bit), and why a byte transfer (8-bit) wouldn't be workable.

[theparitt]

Posted on July 24, 2012 at 02:57

I change VSYNC polarity and HREF polarity to DCMI_VSPolarity_LOW  and DCMI_HSPolarity_Low, then the DCMI overflow interrupt  is gone. 

I aslo change the format of a picture to QCIF  (176x144) pixel per frame. The result from DCMI looks good. It gave me DCMI_Frame Capture complete flag == 1 for Every VSYNC period. However, I still cannot retrieve any data from DMA.  When I read frame_buffer array, I get 0 0 0  0 0 0 for every pixel. Then I tested with DMA interrupt to check whether there is any interrupt signal (complete, error, overflow..... )from DMA.  There was nothing....... no signal from DMA.    I went back to check output signal from my osciloscope. The signals from OV7670 was good...    Whats happen to DMA..? Why there is no response from it?  Could anybody suggest me how to fix this error?Thanks