Camera related Knowledge 1

1.ov7670 photosensitive Whole column 656*488 pixels, of which 640*480 is valid.

2.ov7670 image Output format: VGA, which is a resolution of 640*480 output mode, QVGA, which is the output mode with 320*240 resolution, QQVGA, which is the output mode with a resolution of 160*120.

The 3.PCLK is a pixel clock, and a pclk clock outputs one pixel. VSYNC, which is the frame synchronization signal. Href/hsync the signal synchronously. OV7670 the pixel byte of a frame is 640*480*2, if you want to complete the dynamic display of the requirements of 30 frames/S, then the refresh time of an image is only 1000/30=33.3ms. The acquisition time of each pixel is only 33300000/(640*480) =108ns, and if a pixel is 16 bits, and the data using serial output, then the acquisition time of each pixel only 7ns, so that the speed of grasping the signal, is very few single-chip function to do, But if the data is parallel output, the 8-bit data parallel, grab a pixel two times, or 16-bit data parallel, the overall performance requirements of the microcontroller is relatively low, while the whole system is more stable. We find the OV7670 information that its pixel clock up to 24Mhz, that is, the fastest 42ns can output a pixel, and we press 30 frame/s frame rate of 108ns faster, indicating that the camera can also meet the higher picture and new speed, about the fastest 1s can output 77 pictures.

4. The general microcontroller and the camera communication will be added FIFO, is because the ordinary single-chip computer can not withstand the speed of the camera.

5.SCCB is an ohm's image technology company (OmniVision) developed a bus, three-wire system composed of sccb_e,sio_c,sio_d. Sio_c,sio_d should be added to the pull resistor, the typical value is 4.7K.

6. The camera and LCD display than the column to be consistent, such as the camera 4:3,LCD is 3:4, the full-screen display, you can not get a full view, to full view, you can not display full screen.

Camera related Knowledge 1