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Kwabena Agyeman, 03/13/2012 04:46 pm


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Typical Uses

One of the primary uses of the CMUcam2 is to track or monitor colors. The best performance can be achieved when there are highly contrasting and intense colors. For instance, it can easily track a red ball on a white background, but it would be hard to differentiate between different shades of brown in changing light. Tracking colorful objects can be used to localize landmarks, follow lines, or chase moving beacons. Using color statistics, it is possible for the CMUcam2 to monitor a scene, detect a specific color, or do primitive motion detection. If the CMUcam2 detects a drastic color change, then chances are something in the scene changed. Using “line mode,” the CMUcam2 can generate low resolution binary images of colorful objects. This can be used to do more sophisticated image processing that includes branch detection, or even simple shape recognition. These more advanced operations require custom algorithms to post process the binary images sent from the CMUcam2. As is the case with a normal digital camera, this type of processing might require a computer or at least a fast microcontroller.

Typical Configuration

The most common configuration for the CMUcam2 is to have it communicate to a master processor via a standard RS232 serial port. This “master processor” could be a computer, PIC, Basic Stamp, Handy Board, Brainstem or similar microcontroller. The CMUcam2 is small enough to add simple vision to embedded systems that cannot afford the size or power of a standard computer based vision system. Its communication protocol is designed to accommodate even the slowest of processors. If your device does not have a fully level shifted serial port, you can also communicate to the CMUcam2 over its TTL serial port. This is the same as a normal serial port except that the data is transmitted using non-inverted 0 to 5 volt logic. The CMUcam2 supports various baud rates to accommodate slower processors. For even slower processors, the camera can operate in “poll mode”. In this mode, the host processor can ask the CMUcam2 for just a single packet of data. This gives slower processors the ability to more easily stay synchronized with the data. It is also possible to add a delay between individual serial data characters using the “delay mode” command. Due to communication delays, both poll mode and delay mode will lower the total number of frames that can be processed in one second. Frame resolutions are not affected by serial delays or the baud rate as they were in the original CMUcam1.


