Hardware Assist

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.

if you are firm with FPGA's and maybe verilog:
github.com/multigcs/LinuxCNC-RIO/

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

If you decide not to do this from scratch, a 7I92TM+ 7I77 or 6I25+7I77
will work and are available.

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