Joe's 1000x600x200 steel and aluminium router started

[Kitwn]

Ok your Stupid. . . .But so am I because I'm not seeing it either.?

Actually that should be "Ok you're Stupid' but the grammar police will let you off just this once

What confused me was the homing being set by the release of the switch. I only speak LinuxCNC which sets the homing on the (second) activation of the switch after the gantry has backed off and run in again slowly. An upgrade to version 2.8 includes the ability to have two separately controlled motors with their own switches to square the gantry. Then it runs off the switches by a set distance which can be slightly different for the two sides to fine-tune the squaring.

Yes, that is the whole point of this board I made, it enables the use of a single axis controller output and single home input to safely drive and also correctly home/resquare a dual motor axis with dual home switches. The controller executes its normal procedures without any knowledge that there are two motors and two switches.

That's basically what my board was designed to do but I opted to create all-new step pulses while the controller believed the machine was stationary. It also acted as the splitter for sending the pulses from one output axis of LinuxCNC to two motor drivers during normal operation. 'Great minds', eh?

[devmonkey]

That's basically what my board was designed to do but I opted to create all-new step pulses while the controller believed the machine was stationary. It also acted as the splitter for sending the pulses from one output axis of LinuxCNC to two motor drivers during normal operation. 'Great minds', eh?

Great minds! I just wanted the controller to stay in control at all times so I figured this approach was simpler and possibly a bit safer and it squares the axis as part of the controllers normal homing process. Not sure on the pros/cons of detection on approach vs retraction so long as it is done super slow I don't think it matters, may make more of a difference with mechanical switches.

I did notice a problem with my board yesterday, it was generating a spurious step every few seconds and you could hear them as faint ticks on the stepper whilst it was running. This was due to common mode noise on the step differential line, and is because I didn't bother to put a differential line receiver on the input lines, rather both the +ve and -ve signal are referenced to GND on the arduino. It was fixed by debouncing the inputs over 1 cpu cycle 62.5ns, i.e. reading them twice. However I think I will make a new board in a few days that properly terminates the differential signals, works well enough as it is to to get the machine working now. Any thoughts on the pros/cons of using a opto to terminate the differential signal like the stepper drivers do vs a proper line receiver?

The next step is work out how to bury these proximity sensors in the machine, the Z will be a bit tight and I may need to source a much smaller switch.