[Willoubu]

Hello All,

I'm trying for months to found an answer on this forum about the end switch problem I meet from long time now.
I found several good tips who improve the behavior of my home made CNC but still the same issue.

I still have end switch detection despite all optimisations and the implementation of optocouplers with two diffenrents power supply.

My current configuration is the one in the joined file (best solution from GRBL github site)

I have 10cm of cable between the optocouplers and the Arduino nano board.
I have the issue even if the spindle is turned off.

I tried to replace the Arduino, motor cable with larger ones, add ferrites,

I don't know what else I could do...

If you have any idea I 'll take it.

Thank you

William

[CitizenOfDreams]

Your implementation seems to be correct, except I would use a 24V or at least a 12V power supply for the switches (and change R4/R5/R6 accordingly).

So what kind of problems do you have with the switches, false triggering? What kind of switches are they? Mechanical or inductive? Normally open or normally closed?

[Willoubu]

Hello,

thank your for your answer.

Yes I think about to replace 5v by 24v, I'll try it tonight.
The problem i have is false triggering, I use mechanical switch normally open.

I have observed that by adding a 100nf capacity between the arduino pin and the ground improved the situation.
This is why I thought that the problem was between the octocouplers and the arduino board.
I also tried the pull-up resistor but this doesn't improve anything.

William

[CitizenOfDreams]

I have observed that by adding a 100nf capacity between the arduino pin and the ground improved the situation.
This is why I thought that the problem was between the octocouplers and the arduino board.

Not necessarily. The 100nF capacitor filtered out the short false pulses, but those pulses could have been occuring either before or after the optocouplers.

Here is what you can try: place a short across the optocoupler's input. If you still have false triggering with the optocoupler input shorted, then you know the problem is on the Arduino side.

[Willoubu]

Ok, thank you i'll try tonight.

[Willoubu]

But If i put a short across the optocoupler's input, it will appears as a limit detection ? Circuit will be closed ?

Maybe I haven't catch what you mean by a short

[CitizenOfDreams]

But If i put a short across the optocoupler's input, it will appears as a limit detection ? Circuit will be closed ?

If you place a short across the optocoupler input, the limit will never activate. A short meaning a jumper, a piece of wire.

[Willoubu]

ok.... I got in mind to put a short on the Switch and not on the octocoupler...
I'll try it, thank you