Looks impressive for the money ?

**Doddy** · 17-07-2021

Originally Posted by Fivetide

I'll give this a go tonight when I get 20 mins spare then report back

Yeah, that's a good test set up.

**Fivetide** · 17-07-2021

Originally Posted by Doddy

FiveTide - I've offered you my phone number on PM. Or we can continue this thread here. One way is faster than the other.

Ignore the frequency - that's a characteristic of that board that converts PWM to analogue. If you've cancelled that order, that issue is off the table.

I really need to understand from you how much you understand what PWM is (a variable mark-space signalling standard) and TTL levels (simply a digital 0/1 representation though there are particular voltage level connotations that we can probably safely ignore given the rail-to-rail drive of the Arduino outputs). The question that needs to be resolved is: If you tie the TTL input to 5V, does the laser emit 100% power, and if tied to 0V does the laser emit 0% power (off). If that's happening, then the laser is fundamentally working.

Next, we need to establish - if your GRBL is trying to lase at 100% power, is the PWM output from the Arduino substantially "on" (maybe > 95% mark/space). And similarly at each power level (e.g. 50% = 50% mark/space). That confirms the behaviour of the GRBL controller.

Then you plug them together and check that still works. Back of my mind I'm cautious about any loading from the laser onto the Arduino output. TTL implies a current source level that the Arduino can comfortably handle. But the proof of that is scoping the D11 output signal. I'm also hesitant for any voltage droop on the PSU under the full load drive from the laser. Again, that's a scope job.

Thanks for the offer, I'll try and adjust the PWM output via the Arduino library's as in the video above. If unsuccessful I'll call you probably tomorrow evening if that's convenient ?

**m_c** · 17-07-2021

One thing I've not seen mentioned, is how are the laser and arduino powered, and are they suitably connected?

If both are powered from the same 12V supply, they should already share a common ground, but if you're powering them independently (i.e. 12V to the laser, but relying on USB power for the Arduino), then you'll need to connect the Arduino ground to the laser/12V ground. Without that connection, the TTL/PWM control circuit won't be complete, and nothing will likely happen.