Is it possible to equip a robot with two microcontrollers with two battery packs? Utilizing only one controller and two recievers with the same frequency crystal. Also if this is possible, is it legal in competitions?
i don’t think my first post went through, so sorry if i posted twice:
I’m 99.9% sure it will.
However, I doubt it is competition legal, as it is essentially ‘two’ robots. 
I have wired two batteries to go to one robot, so you could just reverse it and make one battery go to two robots. However you might not get enough power.
Yes, this is essentially making two robots that run on the same freq. I did this once to make a robot with a turreted arm. One micro/battery ran the drive section and the turret base, and the other one ran all the stuff mounted on the turret.
Can’t help you there, but I recommend you look at the rules for whichever competition you’ve entered. They are usually pretty clear about such things - if not, then you should contact the organization running the competition to get a definitive answer.
Cheers,
- Dean
I’m very new to this I hae been tinkering with tech for quite a while but I’m getting into vex as a way to get my daughters involved with technology. I they are very interested even though they are very young and come up with some interesting questions. My six year old was the one who thought up using multiple micro controllers with one remote. We wanted a robot that had good speed and awesome torque. I know that throwing too many motors on one battery/micro controller setup causes them to draw too much amperage. I so she suggested adding another. (And yes it is really interesting explaining all of this to a five and a six year old where they can understand it)
I was thinking that if you programmed two micro controllers for the exact same purpose and configured them the same way. You might be able to utilize two same frequency crystals to use one controller so that you might be able to double the number of usable motors without any detrimental effects.
Welcome to Vex - we have a good community here with lots of experienced folks willing to offer advice and help get you over whatever hurdles you encounter. I got into Vex partly for the fun, but also to help teach my kids (8 & 10) some engineering in a fun way.
Thats really impressive! You explained the constraints to her and she neatly saw through these limits to a solution. That obviously requires imagination (or too little experience to know better ;)), but it also required her to really grasp the constraints.
Yep - seems like a perfectly reasonable approach. The two micros might not be in perfect sync, so the motors might not start/stop at exactly the same times, or run at exactly the same speed. In practice, I doubt you’ll be able to tell any difference. Just make sure both batteries are in a similar state, or one set of motors will wind up bearing more of the burden.
A more evolved approach would be to link the two micros via serial ports and have one programmed as a slave to the other. That would take some real programming in MPLAB (don’t think you can get to serial in EasyC), so not really suitable for 6yr olds.
Let us know how it works out for you,
- Dean
I haven’t really been showing them the programming yet. Its a bit advanced for them. But they do come up with some pretty amazing things. It’s kind of funny we’re going through the inventors guide and I get to break down all of the concepts in there for them. they loved the square bot.
As for the second micro controller I have to order it still. They both want to put three motors per wheel on a four wheel robot. I’m still working on the design with them and they do what they can as far as assembly and Engineering. It’s a lot of fun.
Thanks for the suggestions. If anything I’ll have an extra couple of parts.
If you’re not going to be doing any programming, the signal splitters are cheaper and smaller.
http://www.vexrobotics.com/vex-robotics-signal-splitter.shtml
You can use a PWM cable between the two controllers and use the digital in and out in order to use both controllers at the same time. That is the best way of doing this but it is complex.
It was definitely not legal in this year’s FTC game, it might be legal in other competitions but I frankly would not think it would be allowed. That whole technically being 2 robots is going to be problematic.
Another way is to use 2 PWM cables between the TX/RX ports, but it would be rather complex for a non-experienced programmer to send/recv bytes, etc.