Hello,
I'm an instructor of Robotics. I've been using a robotics learning platform called www.vexrobotics.com for years. I'm trying to replace their 'canned' microcontroller with an Arduino. 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...
profmason.com
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
tim_callinan:
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.
No need for concern. The internal pull-up is just for such an occasion.
Have you compared your design to this existing VEX shield?
https://code.google.com/p/vexmas-shield/
Thanks for the quick answer John. I appreciate the link also. I saw that before but I'm actually trying to learn some basic PCB layout skill on Eagle so its a good little project for me. Tim
Hi John & Co,
I'm still working on my Vex robotics shield. I'm planning on using a screw terminal to provide the main DC power to the shield and will also connect this to the Vin on the arduino. My concern is using a screw terminal - the student might connect the battery the wrong way. The only way I can think of stopping this is being proactive with them or designing something on the shield to protect it. A diode in the right place would help but because this shield is running motors - the diode would need to be pretty big - I would think at least 4A. Does anyone have any opinions on this. Thank you so much for any advice.
Tim
Tim,
If you are still working on this, you can use a MOSFET instead of a diode. See: http://www.instructables.com/id/Reverse-polarity-protection-for-your-circuit-with/
Advantages are revers polarity protection + very low voltage drop. You need to pick the correct MOSFET based on your supply voltage and max current.
Bob