After several weeks of reading, experimentation, search, and more experimentation, the CMUCam2+ finally worked with the Basic Atom module. It even worked with the Basic Atom Pro module without any changes necessary. For those that have worked with both the Basic Atom and Basic Atom Pro, this concern will sound familiar - for those that have not, the problem is simply that the Basic Atom Pro chip is not based on a Microchip Pic as the Basic Atom is and thus it has different characteristics and quirks. Fortunately, none of those quirks surfaced in this case.
Shown is a view of the CMUCam 2+ board that is available from Acroname. Most of the information needed on this sensor can be obtained from either Acroname or Carnegie Mellon University. Carnegie Mellon University developed the technology that the CMUCam 2+ is based on and licenses it.
The first tip to getting the CMUCam2+ working with a Basic Atom module is to buy or build a RS232 to TTL interface to allow connecting the CMUCam 2+ to a computer. Acroname offers a RS232 to TTL interface, but Futurlec has a similar module for less than $5.00 as of 12/2007. The GUI for the CMUCam devices is invaluable and essentially required for focusing the lens and assessing the light levels needed for accurate detection. There are models of the CMUCam that include the RS232 interface, but they are a little bulkier.
Now connect the GND’s on the Basic Atom module or Atom Bot Board to the CMUCam2+ serial connector, ignore the 5V pin on the serial connector, and connect OUT on the serial connector to your IN input on the Basic Atom module and IN on the serial connector on the CMUCam2+ to OUT on the Basic Atom module.
The baud rate has to be 38400 or less on the Basic Atom for communications to be reliable. Using “I38400” provided the greatest speed that was reliable. The hardware port does not seem to work, even when using an interface chip.
It is crucial to use the following command to the CMUCam 2+ from the Basic Atom for communications to work: “DM 20”. This is a delay command that instructs the CMUCam 2+ to delay before starting a transmission. The DM command had to be “DM 100” for the Basic Atom Pro. The DM command MUST be issued after any RS command (reset) or communications will not work properly—even at lower baud rates.
