I was just browsing over at SparkFun, and noticed what could be an interesting companion controller for benchtop Vex experimentation.
It is basically an Arduino in a nice case and with Vex-compatible connectors. You’ll have to take care what you plug in where, because half the ports are 3.3V and the other half are 5V.
You use a USB cable to power it and provide a serial link to control it.
You can then plug peripherals into it - most Vex products should plug right in and work. You should be able to plug Limit Switches and Bumpers into any port. LEDs and Potentiometers should be used in the 3.3V ports. The light and sonar sensors may work in a 3.3V port, but I’m not sure.
It has some PWM outputs, but they are 0%-100% PWM rather than servo-style PWM, so it couldn’t quite run Vex servos or motors without a bit of reprogramming. SparkFun provides the firmware source, so it should be pretty straight forward to add servo-style PWM to its command set.
Anyway, the price is right if you are looking for a Vex-friendly Arduino to play with.
I’ve just begun resurrecting the ‘Geo-Crawler’, using the Arduino Duemilinov as the base. (that, and I have run into a few snags… (a) the laptop that had VEX Programmer 1.0 is fried, (b) new laptop has Windows 7, and (7a) it won’t install the version 1.0 programming, (7b) the link for the activation code is kaput anyways, and (7c) So-far, I have not been able to find a stable, working driver for any of the prolific USB-to-RS-232 cables. that Win-7 will not reject. (or cables for that matter!) )
I just used a re-work of the Parallax ‘PING))’ software with the VEX Ultrasonic Range finder, and it works fine. (Using the PING)) example file, assigned a 2nd pin as the output cable, leaving the single wire pin as the input cable.) The adruino runs the servo module just fine, with minor tweaking (arduino examples of servo.write(##) 0 to 180 only covers 170-degree range, and seems to peg in the 0-degree point.)
And, despite the ‘Receiver’ being proprietary, someone HAS found the code to decode the output from the radio receiver to convert the digital pattern to something the arduino will understand, without need for the ‘no-brainer’ receiver… So, this should be interesting… Building a VEX but not using the VEX microcontroller. I see a VERY crowded Breadboard!
I have used a vex servo and a vex motor on an Arduino UNO and they work just fine. I’m sure you can use any of the sensors that vex has with the Arduino. You could probably use sensors that vex doesn’t sell with the vex system. We did that for one robot, but it was easier another way since we got the new cortex.
