Use a 500CPR Encoder with Cortex
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Author:  norsmi [ Tue Dec 07, 2010 12:35 pm ]
Post subject:  Use a 500CPR Encoder with Cortex

I'm using an optical quadrature encoder with 500 CPR. With TTL Squarewave output.

I tried to use the embedded encoder input function but failed.
I get values but not reasonable values. Probably because the VEX encoder has a lower CPR?
The encoder has two outputs with low 0V and high 5V.

So is it possible to make some changes in the embedded encoder function or create a new one that works with our encoder?


Author:  jbflot [ Tue Dec 07, 2010 4:07 pm ]
Post subject:  Re: Use a 500CPR Encoder with Cortex

Currently, we only support the official VEX encoders in firmware, which provide 360 CPR. There's some technical info regarding the sensors in this document: ... r-inst.pdf

Author:  neso [ Wed Dec 08, 2010 3:57 am ]
Post subject:  Re: Use a 500CPR Encoder with Cortex

Hello. I'm working with norsmi, thought I'd clarify.

We are using a non-VEX encoder that seems to be generating reasonable values.
Not 100% sure, but I think we have the latest firmware (it came with RobotC 2.30)
When connected to ports designated by the Sensor/Motor Setup as Quadrature encoders, these are the results:
•when the shaft is turned at more or less constant speed, SensorValue[..] oscillates between 2 adjacent values
•when the shaft turning speed is changed, the encoder value jumps to a new value.

This would indicate that SensorValue[] returns a speed measurement (wierd!)... except that the connection between speed and SensorValue[] reading seems non-existant or obscure.
Any help in interpreting these values would be appreciated =)

[edit] It seems our Cortex was merely having a bad day. Starting up the same code a few days later, we get reasonable values out of the encoder's SensorValue[].
Thanks anyway =)

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