Mesa: How to consume TTL input from Glass Scales

Joco
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21 Sep 2018 05:53 #117836 by Joco

Replied by Joco on topic Mesa: How to consume TTL input from Glass Scales

andypugh wrote:
No, the GPIO pins are serially addressed rather than wired direct to the 6i25. That is how the 7i76 can have so many more pins than the 17 data pins on the DB25 connector.

Still learning here ... so the existing encoder inputs that would typically be used for the spindle are direct hooked to the 6i25 or are addressed in some other fashion? Presumably different to the GPIO pins hence why you can't utilise a custom firmware to sample a subset of the GPIO pins are a different rate to the rest of them?

Thanks,
James.

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andypugh
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21 Sep 2018 09:32 #117842 by andypugh

Replied by andypugh on topic Mesa: How to consume TTL input from Glass Scales

"Full" encoders are wired directly back to the FPGA. Though some are 2x multiplexed so that 3 FPGA pins + select can count 2 separate ABZ encoders.

MPG encoders are counted on the daughter board, and the total counts is sent back to the FPGA (as an 8 bit int) every 1mS. (The 8 bits are de-wrapped into a 64-bit int by the LinuxCNC HAL driver)

You may be able to use the MPG encoders for your application.

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Joco
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21 Sep 2018 10:12 #117843 by Joco

Replied by Joco on topic Mesa: How to consume TTL input from Glass Scales

Thanks Andy. Get it now.

Yes could use the MPG encoders but I would like to "do it properly".

Appreciate you taking the time to educate me a bit on this. Now to completed the basic CNC setup so I can make a decision on where to take this angle.

Cheers,
James.

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