Looks impressive for the money ?

[Doddy]

Here's a question or two:-

1) Can you write software on the Arduino?, such as to test the PWM interface to the laser without the GRBL software?

2) If you have an Arduino sketch, can you Upload (compile, link and install) the software into the Arduino?


If Yes/Yes, that's your answer. If No/Yes, then I'll knock something up for you - if you're interested.

[Fivetide]

Just bought one of these

https://www.amazon.co.uk/1-3KHZ-Volt...6541965&sr=8-5

- looks simple conversion. But I'd hope for PWM control or TTL as its more accurate for shading etc. But.. saying that - I might buy another laser just for etching as I bought the 30w mainly for cutting hopefully it can achieve that. Apparently u get better focus and accuracy at lower power with diodes

[Doddy]

Hmmm, that module you linked converts (or claims to convert) a PWM signal into an analogue signal. All three input methods on the laser control board are TTL/PWM. If your intent is to use that board with the laser to control power, I don't understand how the laser is intended to take an analogue voltage.

Edit:

Consider also the Arduino PWM outputs, if using the built in libraries (counter driven PWM) operate around 500Hz.. That module claims 1kHz -> 3kHz operation. Just a health-warning on compatibility.

[Fivetide]

I'm amusing via the PWM/TTL imput?

[Fivetide]

Hmmm, that module you linked converts (or claims to convert) a PWM signal into an analogue signal. All three input methods on the laser control board are TTL/PWM. If your intent is to use that board with the laser to control power, I don't understand how the laser is intended to take an analogue voltage.

Edit:

Consider also the Arduino PWM outputs, if using the built in libraries (counter driven PWM) operate around 500Hz.. That module claims 1kHz -> 3kHz operation. Just a health-warning on compatibility.

I'm getting confused.. on the laser board it only says TTL not PWM I thought it may need a PWM to TTL conversion.

[Doddy]

Aha, get where you're coming from. That board does convert PWM into 0-10V analogue, but that's to support the spindle's VFD 0-10V analogue input. That makes some sense. But the interface to your laser remains a PWM-driven TTL-level input. I'd cancel the Amazon order if I was you for that board.

[Fivetide]

Aha, get where you're coming from. That board does convert PWM into 0-10V analogue, but that's to support the spindle's VFD 0-10V analogue input. That makes some sense. But the interface to your laser remains a PWM-driven TTL-level input. I'd cancel the Amazon order if I was you for that board.

Cancel thanks :)

So how do I increase the bandwidth of the PWM to 1khz - 2khz @Doddy ?

[Fivetide]

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

[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.

[Doddy]

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