Design And Hardware Implementation Of CMOS Image Sensor Testing Platform

With the popularity of smart phones, the requirements for mobile phones with camera are also increasing. The development of high definition image sensors also raises higher requirements for the test platform.In the design and test of the CMOS image sensor, a test platform is needed to transfer the image data from image sensor to PC for the analysis and display. USB2.0 interface is often used to transmit the data to PC because of its excellent performance. For the CMOS image sensor with less than 100 million pixels, USB2.0 interface is capable of the work of transferring the image data. But as the definition of the CMOS image sensor becomes higher and higher, the output rate of the CMOS image sensor becomes larger than the transmission rate of the USB2.0 interface, which leads to the strange behavior of the test platform based on USB2.0 interface.As the USB3.0 interface is still not universally available, one more SDRAM chip is used as an additional buffer to partially solve the data rate mismatching problem between sensor and USB 2.0 interface. The two SDRAM chips serve as ping-pong buffer. While one SDRAM is accepting data from the sensor, the other is sending data to USB interface.By adding two SDRAM chips as buffers before the USB2.0 interface, the maximum input data rate and the stability of the test platform are both increased.