Misbehaving encoders

[Steve_Alaniz]

Originally Posted by nathanww

Actually, the theory that I was referring to was that there wasn't enough difference between the voltage that the encoder sends for HIGH and what it sends for LOW. When we looked at this, it didn't really seem to actually touch either extreme of max/min--so we thought that it might be possible that the control system wasn't seeing these small differences because both the HIGH and LOW fall into what it considers HIGH.



It's the US digital kit encoder


Each encoder's A and B outputs are wired to the signal in on the digital sidecar. We also use the power and ground on one PWM for those connections on the encoder

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First of all, the encoders will send a 0 - 5 V or NEARLY a 0-5V square wave from both A and B channels. So there's no way that theory could be correct... unless you made a mistake building the quad system or the US digital unit is defective. Since you didn't build it and US Digital is primo stuff, both are unlikely. Although I DID have my very first failed USDigital device this year.
You need an o'scope to properly look at the signals for A and B and as I said, they SHOULD be a square wave 90 degrees out of phase with each other. ( At VERY high speeds there might not be time for the signal to drop to 0 or rise to 5 but you didn't say anything that might make me think that is a possibility.)
You said you are using a PWM for power to the encoders? Do you have a jumper on the 6V enable pins for that PWM? Sorry if that seems rudimentary but it a simple mistake that even I... <ahem> .. could POSSIBLY make... in a bizarre set of circumstances... not actually admitting anything you understand.

Steve