LinuxCNC-RIO - RealtimeIO for LinuxCNC based on FPGA (ICE40 / ECP5)

tommylight
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06 Aug 2026 01:30 #348477 by tommylight

Replied by tommylight on topic LinuxCNC-RIO - RealtimeIO for LinuxCNC based on FPGA (ICE40 / ECP5)

1. interference due to bad/not shielded/grounded cabling
2. marginal output signals for the drive optocouplers
3. Tango skipping steps, although LinuxCNC is very good at avoiding this, tango might not be, or LinuxCNC might not be aware that is happening.
Does this also happen at very low feeds/speeds?

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PCW
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06 Aug 2026 02:10 #348480 by PCW

Replied by PCW on topic LinuxCNC-RIO - RealtimeIO for LinuxCNC based on FPGA (ICE40 / ECP5)

Another possibility is marginal timing.

Either too narrow step pulse widths,
or insufficient setup times from DIR change to
STEP or insufficient hold times from STEP
to DIR change.

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viewsat
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06 Aug 2026 03:02 - 06 Aug 2026 03:22 #348482 by viewsat

Replied by viewsat on topic LinuxCNC-RIO - RealtimeIO for LinuxCNC based on FPGA (ICE40 / ECP5)

My tests on both the ICEBreakerV1.0e and Tana Nano9k yielded the same results, not due to the FPGA brand, noise, or settings.
I noticed that the Dir PIN output returns to its original position after the step action is completed. This may be because the DIR operation is not yet complete, but the STEP operation occurs prematurely, causing an error.

Last edit: 06 Aug 2026 03:22 by viewsat.

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