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Unread 23-08-2016, 10:44
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marshall marshall is offline
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FRC #0900 (The Zebracorns)
Team Role: Mentor
 
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Re: CAN to PWM converter?

Quote:
Originally Posted by nickbrickmaster View Post
IIRC, the CAN protocol used for FRC is pretty heavily modified and kept under wraps to prevent tampering.

If you do somehow figure out the protocol, you would need to use a microprocessor to a. spoof a talon SRX and b. translate the commands into PWM values.

I can't really help you with anything, sorry. If you wanted to try to reverse-engineer the protocol, I would start with the firmware files, or maybe see if it's on robotpy's github.
If by heavily modified and kept under wraps you mean CAN spec compliant and out in the open based on the manuals provided by CTRE then you are absolutely right!

http://www.ctr-electronics.com/Talon...e%20Manual.pdf
http://www.ctr-electronics.com/Talon...;s%20Guide.pdf
http://www.ctr-electronics.com/PCM%20User's%20Guide.pdf
http://www.ctr-electronics.com/PDP%20User's%20Guide.pdf

Being that CTRE's devices are the only CAN devices at the moment for FRC motor control (and power and pneumatic) and they offer non-FRC firmware and tons of example code, they are doing a terrible job of hiding any of this.

My smarty-pants response aside, the CAN devices available for FRC teams are pretty well documented and accessible.

Also relevant if you get into CAN jiggery pokery:

Cool device and software for making it a lot easier (CAN is integrated into the Linux Kernel these days though):
http://linklayer.github.io/cantact/

Good talk explaining how CAN works and how to use above device with software (I'm in the audience somewhere):
http://livestream.com/internetsociet...deos/130605456

EDIT: Also, the irony of FRC specific CAN being an undocumented dark art while most of the automotive industry keeps it a closely guarded secret is amusing. Seriously, watch the talk.
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Last edited by marshall : 23-08-2016 at 10:52.
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