catalogue
2.2 configuration register DCI_CTL
2.2.2 clock polarity selection CKS
2.2.3 Horizontal synchronous polarity selection HPS
2.2.4 Vertical synchronous polarity selection VPS
5. Set the pixel size of OV2640
The digital camera interface is a synchronous parallel interface, which can capture video and image information from the digital camera. It supports different
Color space images, such as YUV/RGB, also support JPEG format images of compressed data.
1 IO initialization
DCI generally selects 8bit interface. In addition, OV2640 requires I2C interface setting register.
2 initialize DCI
2.1 enable DCI and DMA1
RCU_AHB2EN |= ((uint32_t)1 << 0); //Enable DCI RCU_AHB1EN |= ((uint32_t)1 << 22); //Enable DMA1
Generally, DMA function is used when DCI is used. DCI corresponds to channel 1 or channel 7 of DMA1. Channel 7 is used here
2.2 configuration register DCI_CTL
2.2.1 snapshot mode SNAP
0: continuous capture mode - continuous capture of camera data
1: Snapshot mode- Only a single frame is captured. After receiving the complete first frame, the camera interface will be automatically disabled
2.2.2 clock polarity selection CKS
0: falling edge capture
1: Rising edge capture
2.2.3 Horizontal synchronous polarity selection HPS
0: low level during blanking
1: Blanking period high level
2.2.4 Vertical synchronous polarity selection VPS
0: low level during blanking
1: Blanking period high level
2.2.5 Data format DCIF
00: each pixel clock captures 8 bits of data
01: capture 10 bits of data per pixel clock
10: Each pixel clock captures 12 bits of data
11: Each pixel clock captures 14 bits of data
2.2.6 Frame frequency FR
In the continuous capture mode, FR defines the frame capture frequency
00: capture all frames
01: capture every other frame
10: Capture every three frames
11: Reserved
2.3 configuring DMA
Two DMA channels can be used for DCI, i.e. channel 1 and channel 7 of DMA1
DMA_CHFCTL(DMA1, CAMERA_DMA_CH) = 0;
DMA_CHCTL(DMA1, CAMERA_DMA_CH) = 0;
DMA_CHFCTL(DMA1, CAMERA_DMA_CH) &= ~((uint32_t)1 << 2); //Disable Multi Data Mode
DMA_CHPADDR(DMA1, CAMERA_DMA_CH) = (uint32_t)&DCI_DATA;
DMA_CHM0ADDR(DMA1, CAMERA_DMA_CH) = ramAddr;
DMA_CHCNT(DMA1, CAMERA_DMA_CH) = (uint32_t)CAMERA_SIZE_W * CAMERA_SIZE_H * stride / 4;
value = DMA_CHCTL(DMA1, CAMERA_DMA_CH);
//bit6-7: channel transfer mode
//bit11-12: transfer data width of peripheral
//bit13-14: transfer data width of memory
//bit16-17: channel priority level
value &= ~((uint32_t)0x03 << 11 | ((uint32_t)3 << 13) | ((uint32_t)3 << 16) | ((uint32_t)3 << 6));
value |= (((uint32_t)2 << 11) | ((uint32_t)2 << 13) | ((uint32_t)2 << 16) | ((uint32_t)0 << 6));
//bit9: next address generation algorithm of peripheral
value &= ~((uint32_t)1 << 9); //Disable Peripheral's Address Auto Increasing.
//bit10: next address generation algorithm of memory
value |= ((uint32_t)1 << 10); //Enable Memory's Address Auto Increasing.
//bit8: DMA circular mode
value |= ((uint32_t)1 << 8); //Enable DMA Circular Mode
//bit25-27: peripheral enable
value &= ~((uint32_t)0x7 << 25);
value |= ((uint32_t)0x1 << 25); //Peripheral 1(DCI is 1) is enable.
DMA_CHCTL(DMA1, CAMERA_DMA_CH) = value;ramAddr is the RAM space allocated to DCI in MCU. For example, here is an array
#define CAMERA_SIZE_W 320 #define CAMERA_SIZE_H 240 EXTERN uint16_t gCameraBuf[CAMERA_SIZE_W * CAMERA_SIZE_H];
The camera adopts RGB565 format, and one pixel corresponds to two bytes, so uint16 is used here_ T defines this array variable, corresponding to stripe = 2 (that is, RGB565 is 2 bytes).
2.4 configure clock output
reg = RCU_CFG0;
#if (PIN_DCI_XCLK == 8)
/* reset the CKOUT0SRC, CKOUT0DIV and set according to ckout0_src and ckout0_div */
reg &= ~(RCU_CFG0_CKOUT0SEL | RCU_CFG0_CKOUT0DIV);
RCU_CFG0 = (reg | RCU_CKOUT0SRC_HXTAL | RCU_CKOUT0_DIV3);
#else
reg &= ~(RCU_CFG0_CKOUT1SEL | RCU_CFG0_CKOUT1DIV);
RCU_CFG0 = (reg | RCU_CKOUT1SRC_HXTAL | RCU_CKOUT1_DIV3);
#endif3. Enable DCI
void dciEnable(void)
{
DMA_CHCTL(DMA1, CAMERA_DMA_CH) |= ((uint32_t)1 << 0 | ((uint32_t)0x1 << 4)); //DMA_ENABLE
DCI_CTL |= ((uint32_t)1 << 14); //DCI enable
DCI_CTL |= ((uint32_t)1 << 0); //DCI capture enable
}It mainly enables DMA and DCI.
4. Initialize OV2640
void ov2640Init(void)
{
uint8_t buf[1];
uint16_t i;
bool_t status = 0;
/* OV2640 reset */
buf[0] = 0x01;
status = i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, 0xff, buf, 1);
if(status == FALSE)
{
OV2640_INFO(Printf("ov2640 init fail 1\n"));
}
buf[0] = 0x80;
status = i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, 0x12, buf, 1);
if(status == FALSE)
{
OV2640_INFO(Printf("ov2640 init fail 2\n"));
}
delayms(10);
for(i = 0; i < sizeof(ov2640_svga_init_reg_tbl) / 2; i++)
{
status = i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, ov2640_svga_init_reg_tbl[i][0], (uint8_t *)&(ov2640_svga_init_reg_tbl[i][1]), 1);
if(status == FALSE)
{
OV2640_INFO(Printf("ov2640 init fail 3:%d\n", i));
break;
}
}
delayms(100);
for(i = 0; i < sizeof(ov2640_rgb565_reg_tbl)/2; i++)
{
status = i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, ov2640_rgb565_reg_tbl[i][0], (uint8_t *)&(ov2640_rgb565_reg_tbl[i][1]), 1);
if(status == FALSE)
{
OV2640_INFO(Printf("ov2640 init fail 4:%d\n", i));
break;
}
}
delayms(100);
}5. Set the pixel size of OV2640
The pixel size of OV2640 must be 4 multiples
void ov2640SetSize(uint16_t w, uint16_t h)
{
uint16_t outh;
uint16_t outw;
uint8_t buf[1];
if((w % 4) > 0)
return;
if((h % 4) > 0)
return;
outw = w / 4;
outh = h / 4;
buf[0] = 0x00;
i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, 0xff, buf, 1);
buf[0] = 0x04;
i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, 0xE0, buf, 1);
buf[0] = outw & 0xFF;
i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, 0x5A, buf, 1);
buf[0] = outh & 0xFF;
i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, 0x5B, buf, 1);
buf[0] = (outw >> 8) & 0x03;
buf[0] |= (outh >> 6) & 0x04;
i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, 0x5C, buf, 1);
buf[0] = 0x00;
i2cWrite(I2C_CAMERA, OV2640_ADDRESS, 8, 0xE0, buf, 1);
}6. Initialize the camera
Finally, the content of the camera is displayed on the TFT screen, so the data needs to be displayed on the TLI.
tliLayer_t layer;
ov2640Init();
Printf("OV2640 ID:%x\n", ov2640GetID());
ov2640SetSize(CAMERA_SIZE_W, CAMERA_SIZE_H);
dciEnable();
delayms(100);
layer.alpha = 0xFF;
layer.bufAddr = (uint32_t)gCameraBuf;//(uint32_t)0xC0000000;
layer.defalutColor = 0x00FFFFFF;
layer.format = FORMAT_RGB565;
layer.x = 0;
layer.y = 0;
layer.w = CAMERA_SIZE_W;
layer.h = CAMERA_SIZE_H;
tliLayerInit(0, layer, 1);