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Unread 28-11-2008, 02:53
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VEX Robotics Engineer
AKA: Arthur Dutra IV; NERD #18
FRC #0148 (Robowranglers)
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Re: Using vex micro controller with hobby shop receiver?

Quote:
Originally Posted by kajeevan View Post
Here is the problem, I am a complete novice at electrical/programming. I have a vex micro controller and a 2.4Ghz Park Flyer receiver. The receiver had a pwm connection. Is it possible to connect it into a digital input and receive it, that way i can use there controller and still program my vex motors.

If so how would the program look. Also is it possible to hook up victors running 2 cims into the micro controller.

Also how would I run battery for it. I need a 7.2V for the micro controller and a 12V for the cims.

Site of receiver:

http://www.horizonhobby.com/Products...odID=SPM2460BR
To use their R/C connection to control the Vex controller would work with quite a bit of coercion (by means of custom control circuits). But their is an easier way to do this for relatively cheap.


Note: I have not actually done this yet, but I plan to do it soon with both Vex controllers and Arduinos:

One relatively easy way to wirelessly talk to a Vex controller without the Vex R/C equipment would be to use ZigBee (XBee) wireless nodes.If you want a really simple way of controlling it, you can splice into the analog sensor pots on the back of the Vex transmitter as well as the digital buttons, and feed these values to the XBee module. (Note: Vex transmitter joystick pots run at 5v, the XBee modules use 3.3v. You will need a potentiometer or do the math [and save the world] to calculate an appropiate voltage divider using resistors.)

Since the XBee modules have a "transparent" mode, in which whatever value put on the input pin of the transmitter gets sent to the receiver, you can connect the output pins of the XBee module on the robot directly into the analog/digital I/O ports on the Vex controller.

Now if you want to get fancier, you can add a small controller to the Vex transmitter (such as the ever-famous $20ish Ardunio) to encode the joystick and buttons values into a serial communications stream, and send this over the serial pin. On the Vex robot, you would then wire this over to the Rx port. You can use the Tx port to send data back to the transmitter, and do stuff like light up LEDs or whatever you want.

1mW XBee modules are about $20 each, and you would need two. 1mW XBee modules have a range of about 100-300 feet. If you want to get more advanced and use an Ardunio (or similar system on the transmitter) or use higher power XBee PRO modules (60mW are $35 each, and have a range of up to a mile outdoors), obviously this will cost more. But who wouldn't want to control a Vex robot a MILE away?

You can find XBee/XBee PRO, as well as Arduino controllers over at www.sparkfun.com.
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Art Dutra IV
Robotics Engineer, VEX Robotics, Inc., a subsidiary of Innovation First International (IFI)
Robowranglers Team 148 | GUS Robotics Team 228 (Alumni) | Rho Beta Epsilon (Alumni) | @arthurdutra

世上无难事,只怕有心人.