Comment by bubaumba

Comment by bubaumba a year ago

9 replies

I played with it years ago, but it's still alive and well

    http://linuxcnc.org/
These days not sure, hard to find computer with parallel port. Combined version with microcontroller like raspberry pico (which costs < $10) should be the right way to do it. Hard real time, WiFi remote for cheap. Then computer doesn't need to be fat or realtime, almost anything, including smartphone.
HeyLaughingBoy a year ago

That and Linux-capable ARM System-on-Modules that also have a built-in microcontroller core to run real-time control separately are very popular these days.

alangibson a year ago

Most people use LinuxCNC with cards from Mesa now. They have various versions for Ethernet, direct connect to Raspberry Pi GPIO, etc.

GeorgeTirebiter a year ago

USB to Parallel are common. so, easy.

  • cwillu a year ago

    A “real” parallel port provides interrupts on each individual data line of the port, _much_ lower latency than a USB dongle can provide. Microseconds vs milliseconds.

    • YZF a year ago

      A standard PC parallel port does not provide interrupts on data lines.

      The difference is more that you can control those output lines with really low latency and guaranteed timing. USB has a protocol layer that is less deterministic. So if you need to generate a step signal for a stepper motor e.g. you can bit bang it a lot more accurately through a direct parallel port than a USB to parallel adapter (which is really designed for printing through USB and has very different set of requirements).

      • cwillu a year ago

        Are you sure about that? I'd have bet money that the input lines have an interrupt assigned, and googling seems to agree.

        • YZF a year ago

          I used the parallel port extensively. I've had the IBM PC AT Technical Reference that had a complete reference to the parallel port. I've read it many times.

          But alas, it was decades ago, so it's possible I'm wrong ;)

          This is the closest reference I can find: https://www.sfu.ca/phys/430/datasheets/parport.html

          The card does have an interrupt but only the ACK signal can interrupt. Not the Data lines. ACK makes sense since it would be part of the printing protocol, you'd send another byte each interrupt.

    • bubaumba a year ago

      I think it's possible do to it all on raspberry pico. Having pico doing low level driving and javascript in browser taking high level, feeding pico and providing UI. That would be close to perfect solution