Here's what I do and what Matt was referring to in his post. See if the snapshots I took help make the wiring clear.
- Male-to-male PWM-style cables are needed (purchase, combine old cables, or make your own).
- Camera power can come from any regulated +5v pin on the Vex controller (all the middle pin positions). Driving servos directly from the CMUcam requires the extra power available from the unregulated Vex motor outputs. Use a regular male-to-male PWM cable.
- Serial communication is simplest from the native CMU TTL port to the nativeVex TTL port. It’s cleanest with a 4-pin housing at the camera end, but you can rig a solution from a pair of 3-pin connectors or a 3-pin/single unhoused pin combination too. The Vex end needs two side-by-side connectors, because the Vex TX/RX pins are themselves side-by-side.
- Carefully note the location of each TTL port pin in Thumbnail 2 and avoid the CMUcam2 TTL port power pin, so you’ll need a 4-pin connector with the third pin missing.
- Note the Tx of one device is connected to the Rx of the other, so:
- Ground-to-ground
- CMU Rx to Vex Tx
- CMU Tx to Vex Rx
- See Thumbnails 1 & 3 for photos of the wiring. Note however that the green Rx wire leaving the CMUcam2 arrives at the Vex controller as a white wire, because I added a male-to-male cable. I made sure you can see the Tx/Rx labels where numbers normally are in Thumbnail 3.
For software Kevin has an EDU version that will work or it's a pretty simple transition if you want to move existing FRC code over. See http://www.chiefdelphi.com/forums/sh...92&postcount=2
We don't run the servos from the CMUcam2 board, but if you choose to then take the camera power from the Vex motor outputs for the extra voltage (unregulated-straight from the battery). We tend to prefer the consistency of the regulated 5v from any of the other Vex outputs, but it's inadequate to also power servos driven directly from the camera. It's a personal choice to not use the CMUcam's servo control capabilities because the uses we put the camera to sometimes involve servos and sometimes don't and when we do use them we want to control the programming.
Quote:
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Originally Posted by foobert
is there a reason to not just use the programming cable? ... or did ifi obfuscate the functionality to the point that it won't work for plain old serial comms?
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You can use the programming port as well if you prefer and even run two cameras easily.