DCMI camera interface program with DMA with STM32f4-discovery board

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