Programmer's View of Cpia2Cpia2 is the second generation video coprocessor from VLSI Vision Ltd (now adivision of ST Microelectronics).  There are two versions.  The first is theSTV0672, which is capable of up to 30 frames per second (fps) in frame sizesup to CIF, and 15 fps for VGA frames.  The STV0676 is an improved version,which can handle up to 30 fps VGA.  Both coprocessors can be attached to twoCMOS sensors - the vvl6410 CIF sensor and the vvl6500 VGA sensor.  These willbe referred to as the 410 and the 500 sensors, or the CIF and VGA sensors.The two chipsets operate almost identically.  The core is an 8051 processor,running two different versions of firmware.  The 672 runs the VP4 videoprocessor code, the 676 runs VP5.  There are a few differences in registermappings for the two chips.  In these cases, the symbols defined in theheader files are marked with VP4 or VP5 as part of the symbol name.The cameras appear externally as three sets of registers. Setting registervalues is the only way to control the camera.  Some settings areinterdependant, such as the sequence required to power up the camera. I willtry to make note of all of these cases.The register sets are called blocks.  Block 0 is the system block.  Thissection is always powered on when the camera is plugged in.  It containsregisters that control housekeeping functions such as powering up the videoprocessor.  The video processor is the VP block.  These registers controlhow the video from the sensor is processed.  Examples are timing registers,user mode (vga, qvga), scaling, cropping, framerates, and so on.  The lastblock is the video compressor (VC).  The video stream sent from the camera iscompressed as Motion JPEG (JPEGA).  The VC controls all of the compressionparameters.  Looking at the file cpia2_registers.h, you can get a full viewof these registers and the possible values for most of them.One or more registers can be set or read by sending a usb control message tothe camera.  There are three modes for this.  Block mode requests a numberof contiguous registers.  Random mode reads or writes random registers witha tuple structure containing address/value pairs.  The repeat mode is onlyused by VP4 to load a firmware patch.  It contains a starting address anda sequence of bytes to be written into a gpio port.