Change speed or halt based on TTL input


I would like to trim thickfilm resistive material with my laser and need to be able to slow down, change to next cut, or stop cut when the resistance gets close to nominal (change speed or change cut) and when the fine trim completes to be able to halt the cut.

I’m hoping to be able to do this with a TTL input or something.

Are there any unused inputs on the cohesion3d board? If so where can I find technical documentation on the board? I’ve only seen high level documentation.

Thank you for your help and time.

Trent Spencer - KM4YTU

Hi Trent,

This is a highly unique thing you are wanting to do. Reading resistance would require an analog input, not a TTL (digital) one, which may not be available at all, and there is no firmware support for any of the things you have described.

Our documentation is about how to do specific laser things with the LaserBoard, as this is what the vast majority of our users are doing.

I’m sorry, I wasn’t as clear in describing my needs as I should have been. I am reading the resistance with an LCR meter and have made an interface board that can give either a high or low output when a given threshold has been passed. I would like to use 1 (or 2 if possible) of these outputs to at the very least stop/pause the current laser trim…if possible I would like to -with the use of two separate signals- first skip to the next cut, then stop the cut when the next signal is sent.

I understand that this is a very niche need and this particular use case is unlikely to have happened. I was hoping that there were unused gpio that might be easily accessed and used.

Thank you for your time and response.

Best regards,
Trent Spencer - KM4YTU

Any unused endstop pins can be used as generic digital GPIOs, but in order to do this you’d need firmware support, so that’ll mean hacking directly on Smoothie or GRBL-LPC to get the functionality you need baked in. It’s also not something LightBurn will respond to, either. This would very likely need a custom GCode streamer that could read the status and act appropriately.