Vex Robotics and Arduino

Hello,
I’m an instructor of Robotics. I’ve been using the Vex robotics system for years. My students and I absolutely love the Vex system but I’m trying to replace the Cortex with an Arduino. I think this would benefit the students. In order to do this, I need to design myself a shield to sit upon the arduino to allow the sensors and motors to easily interface with the arduino. Here is an example of one…
http://profmason.com/?p=9412
I’ve tested all of the Vex sensors with the arduino and the one sensor I’m having trouble with is the simple PushButton.
http://www.vexrobotics.com/vex/products/accessories/sensors/276-2159.html
I’ll get to the point. Essentially the push-buttons are a single pole single throw. In order to get them working - i need a pull-up or pull-down resistor. In order to design a shield to do this - this adds a little bit of complexity which i would rather not have to add.
I have also tried a software version of a pull-up resistor. http://arduino.cc/en/Tutorial/InputPullupSerial
This works and i would like to do this but I’m a little concerned. Thank you for any help.
Tim

I’ve tested all of the Vex sensors with the arduino and the one sensor I’m having trouble with is the simple PushButton.
http://www.vexrobotics.com/vex/products/accessories/sensors/276-2159.html
I’ll get to the point. Essentially the push-buttons are a single pole single throw. In order to get them working - i need a pull-up or pull-down resistor. In order to design a shield to do this - this adds a little bit of complexity which i would rather not have to add.
I have also tried a software version of a pull-up resistor. http://arduino.cc/en/Tutorial/InputPullupSerial
This works and i would like to do this but I’m a little concerned. Thank you for any help.
Tim

Just wondering why do you want to swich to Arduion?

I’ve thought about this for years and I’ve finally made the decision to do this. I teach at a community college but I don’t think that really matters. The main reason would be when the students leave they will never see a cortex in industry at least with the arduino they are way more commonplace. Also I would expect studetns to purchase and use their own Arduinos in class. This was never possible when the cortex cost nearly $300. I think the vex robotics system is awesome but one improvement would be to replace the microcontroller. Also way more shields , way more functionality with the arduino. Hope that answers your question,
Tim

It would work I have done it once before with some work. They main question is what program would you use to program the Arduion. I used robot C wich didn’t take much work to get the firmware on it but if you want to use. Python Ect. It would be a lot of work to get firmware on it.
This is off topic a little but my next post I’ll be a senior member:cool:

It would be nice if somebody could put together a Vexable Arduino for kids to play and experiment with. I saw somebody was working on using an Arduino to control a Vex motor. I’m not sure if he knows how to solve any of your problems with this but you might want to drop him a line.

https://vexforum.com/t/how-to-hook-up-a-vex-motor-to-arduino/27195/1

I’ll also try to solve some problems with it on my own time I’ll get back to you.
Of I do solve some problems I’ll post the code, don’t depend on me not the best with Arduino.

I’ve used VEX and Arduino for a few years now. The input_pullup option works great where a pull up resistor is required for working with a switch.

It is a pretty common option on most microcontrollers, so I wouldn’t be too worried. You are actually using a hardware resistor… just a wee tiny one that is built in to the chip.

Jason

I’m pretty sure Professor Mason shield works with the vex push button already. His students use ROBOTC for arduino I think. http://profmason.com/?p=7000

The Vex products are actually pretty standard components, but wrapped in friendly mounting enclosures. The push button, like you said is just a SPST switch, normally floating but can be configured to be connected to an internal pullup resistor (http://arduino.cc/en/Tutorial/DigitalPins).

I’m pretty sure you don’t need RobotC if you’re going to be working with an Arduino - standard libraries would probably do the same thing (“analogWrite(3,255) or whatever” sets a PWM pin to 255, which you feed to a motor driver power circuit). Ultrasonic sensors, encoders, potentiometers all basically work the same as any other hobby level sensor.

Depending on the Arduino, the only problem you’d really have is how many ports you have. For an Arduino Uno, 6 analog ports, 14 digital ports (6 PWM out, 2 serial pins, 2 interrupts) might just be enough.

You might want to consider something like this rather than a standard Uno.

http://www.ruggedcircuits.com/microcontroller-boards/ruggeduino

I built my own custom shield. Its main purpose was just to be used as a sensor shield. The simplest way i made the switches work with the Arduino was to just open them and solder the red wire.

P.s. Solder job was a little messy, but shield works great!
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Thank you for all the very useful replies. So it sounds like the software controlled Pullup resistor is a go. That was my main concern. I will upload the board files and result when i get them done.
Thanks -Tim

They no longer sell / make this board. There were some similar boards like the Industrino, but were super expensive.

I’ve used these boards and have been pretty happy with them
http://www.dfrobot.com/index.php?route=product/product&product_id=844

Guess I missed the “Sold out” part :frowning: Shame, always thought that was a good idea.

You can design a pull down resistor on the board it just add less modular-ability or you’ll have to have a switch to turn the input from strait to the processor to pull down resister (which is in arduino)


This shows how easy it is to add a pull down resister.

it’s simple and may add more dependability to the arduino but the board would become much more intensive.

I’m in school currently for computer and electrical engineering so If you have more questions about this let me know.

I’ve looked into something similar for vex but haven’t made anything from it yet.

-Jaxon Weis

See also this thread for a similar discussion and a few other product links. Notably, check out the Roboduino as an alternative.

This board is sold in kit form, with the SMT parts are already soldered down but the PTH parts included loose in the packaging. This is actually an advantage in that it lets you install VEX-friendly female headers instead of the male ones it comes with. Of course, you have to be comfortable soldering… I’ve also seen it sold elsewhere fully assembled with male header pins.

Cheers,

  • Dean