Solving the USB Latency Dogma for HMI/MPG: Technical Feedback Request

not knowing how you print your message but how much of your main loop taken up by printing your message? It might not be as bad as you think.
Maybe an exercise for halstreamer?

This issue originated from LinuxCNC and occurred nine times within ~30 minutes.

not sooo bad

Hi everyone, I’ve been away for a few days focusing on the hardware side of the project.

Regarding meister's tests: they are very interesting! They confirm exactly why io_decoder is specifically designed for HMI (MPG, buttons, and operator panels) rather than real-time axis control.

While a 100-200ms jitter is critical for stepper motor timing, it is virtually imperceptible for an operator pressing a 'Coolant' button or turning a feed-override knob. By moving the logic to a dedicated user-space thread in v1.1.0, we ensure that even these USB latencies never interfere with the core LinuxCNC Real-Time performance.

Small update: I’ve just ordered a very limited run of 5 'Ready-to-Use' hardware kits (Core + IN/OUT expansions) for those who want a plug-and-play experience without the hassle of SMD soldering. I'll have them in my hands soon for final testing.

If anyone is interested in being one of the first 5 'beta-testers' for the official hardware, stay tuned!

Some observations:

Lots of people are using USB to Modbus convertors to control spindle VFDs, and that works OK, (it's noticably notchy doing CSS on my lathe, though)

Jepler (long-time LInuxCNC dev, but now left the project) wrote this back in 2007:
emergent.unpythonic.net/01198594294

USB is definitely adequate for any HMI interaction, otjherwise gamers wouldn't be able to use USB keyboards. (I know that _some_ insist on PS2 for less latency, but most don't)

No eBay APP ID and/or Cert ID defined in Kunena configurationHi everyone,Following the technical progress we've discussed regarding USB latency and UDEV permissions, I’ve assembled and tested a first batch of 5 complete kits (Main board + I/O expansions).To be clear on the project structure:

• The LinuxCNC HAL Component is fully Open Source on GitHub (GPLv2).
• The Firmware and PCB Schematics are proprietary and come pre-installed/ready-to-use in these hardware kits.

This is a 'ready-to-go' solution for those who want to implement this HMI/MPG interface without building the hardware or coding the firmware side themselves.eBay Link (5 units available): Looking forward to your feedback on these first units!

I understand this currently comes with 8 digital inputs and 8 digital outputs, besides the analog I/O. If I later wanted to add additional inputs, would it be just a simple matter of stacking on additional input cards and updating my linuxcnc config, or would additional changes be needed?