Hardware Assist

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30 Apr 2024 08:18 #299376 by 3CHman
Hardware Assist was created by 3CHman
Hi all - I'm just trying to plan out what is possible before I get too far into Linuxcnc . Its an old Colchester TriumhCNC lathe. +/-10V velocity control as usual with a 3TRM2 amp. The amp works fine but the old Crusader11 controller is now dust. On the lathe there are two slide encoders plus a spindle encoder. The encoders are fairly modest at 250ppr and the spindle is 1000ppr. Im looking to provide some HW assist with the encoders - the obvious route would be with a Mesa card feeding into a DB25 port but a) you cant get them and b) I would like to have a go myself.  Decoding the encoders into count and direction or whatever is a pretty simple HW task. Im OK with VHDL and can make my own PCB's but the question is - does this sound like a possible route to take. Would it be possible to generate a hal layer to receive such an interface. I'm pretty flexible about what the interface might be at the mo. Just trying to sus out what may be possible, Thanks in advance for any assist.

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30 Apr 2024 09:46 #299378 by tommylight
Replied by tommylight on topic Hardware Assist
Mesa 7i85 and 7i85S can do 4 encoders, and can usually be found.
A Mesa 7i92TM or 7i96S with 7i85 and 7i83 and 7i84 is all you would need. 7i96S has some IO so might not need 7i84 at all.

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30 Apr 2024 11:57 #299389 by meister
Replied by meister on topic Hardware Assist
if you are firm with FPGA's and maybe verilog:
github.com/multigcs/LinuxCNC-RIO/

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30 Apr 2024 12:16 #299392 by cornholio
Replied by cornholio on topic Hardware Assist
Mesa firmware is open source, the 7i92 & 7c81 schematics are floating around on the forum. The mesa firmware is available for download on the product page of each board.

Here's one I made earlier:
forum.linuxcnc.org/show-your-stuff/51142...pga-card-9d60#289226

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30 Apr 2024 14:49 #299402 by PCW
Replied by PCW on topic Hardware Assist
If you decide not to do this from scratch, a 7I92TM+ 7I77 or 6I25+7I77
will work and are available.

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02 May 2024 11:54 #299542 by 3CHman
Replied by 3CHman on topic Hardware Assist
Many thanks for your help guys - so so useful. Think Ill go with a bit of belt and braces - get hold of some Mesa cards if I can as a back up for if my attempts fails. Looks as if there is a load of useful info. out there. Regards

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