Looking for Stepgen Index Homing Firmware for Mesa 7i76eu & 7i85S

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24 Aug 2025 16:48 - 24 Aug 2025 17:01 #333862 by jschulze
Hi,
I was hoping someone might have a firmware file for a 7i76eu & 7i85S that enables the stepgen index homing.  Or if anyone has any links on how to make custom firmware I downloaded the source file and found a post with the necessary changes, but I'm not sure how to compile the firmware.

I didn't have enough encoder inputs so I only connected the index signals from my servo drives to the 7i85S encoder inputs.  Thanks in advance for the help.  

X-Axis ---> stepgen.00 --> hm2_7i76e.0.encoder.00.input-a
Y-Axis ---> stepgen.01 --> hm2_7i76e.0.encoder.00.input-b
Y2-Axis ---> stepgen.02 --> hm2_7i76e.0.encoder.00.input-index
Z-Axis ---> stepgen.03 --> hm2_7i76e.0.encoder.01.input-a
A-Axis ---> stepgen.04 --> hm2_7i76e.0.encoder.01.input-b
B-Axis ---> stepgen.05 --> hm2_7i76e.0.encoder.01.input-index
C-Axis ---> stepgen.06 --> hm2_7i76e.0.encoder.02.input-a
Last edit: 24 Aug 2025 17:01 by jschulze.

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24 Aug 2025 21:50 #333874 by PCW
It's a little odd because muxed cards are intended for encoders, so muxed encoders
and muxed stepgen index signals assume that there are an equal number of stepgens
and encoders. This could be fixed by adding a new pin type (muxed stepgen IDX)
but that would also require LinuxCNC driver changes, at least if done right.  

Here is an attempt:

 

File Attachment:

File Name: 7i76eu_7i8...sdid.zip
File Size:302 KB


I believe this has the stepgen index mapping the same as yours
for the first 6 indexes (0..5) , but then uses standard encoder pinout
for stepgen index 6 and 7 (since this allows 2 full encoders with shared
stepgen/encoder index pins) 

So you get 8 stepgen index pins, 3 working encoders (2 on the 7I85S and 1 on the 7I76EU)

A disadvantage of this current scheme will be that you need to enable all the encoders
even though only 3 are actually usable. I will take a look at better support for stepgen index
inputs using muxed cards, but as I mentioned, this will require LinuxCNC driver changes

I will take a look at fixing this but as I mentioned
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25 Aug 2025 01:50 #333877 by jschulze
Thanks so much. I really appreciate it. I'll load it up and give it a try.

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25 Aug 2025 02:49 #333878 by jschulze
Loaded up the firmware, but I'm not seeing the stepgen index-enable pins.  I looked in hal configuration and halcmd show pin in the terminal but I couldn't find them.  Would it make it easier if I picked up another 7i85S so I could have an encoder for each stepgen?  Thanks again for your help.  
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25 Aug 2025 02:59 #333879 by PCW
Did you power cycle the 7I76EU (or use the --reload command)?
 

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25 Aug 2025 03:12 #333880 by jschulze
I loaded it once and power cycled it, couldn't see anything, so I reuploaded the firmware and tried both power cycle and the --reload. I also enabled the additional encoders in my hal file.

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25 Aug 2025 03:21 - 25 Aug 2025 03:34 #333881 by PCW
Sorry,  I got the stepgen version wrong, will retry.


Try this:

 

File Attachment:

File Name: 7i76eu_7i8...8-24.zip
File Size:302 KB



 
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Last edit: 25 Aug 2025 03:34 by PCW.

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25 Aug 2025 03:56 #333882 by jschulze
It worked! I don't have much time right now to play with it, but I was able to manually turn on the stepgen index-enable and it turned off and zeroed the stepgen count with the index signal. Thanks so much for your help with this, it's very much appreciated.

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