Author Topic: Pin 11 PWM remains after image completes  (Read 13909 times)

Zax

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Re: Pin 11 PWM remains after image completes
« Reply #30 on: July 10, 2016, 10:11:21 AM »
I have it in the 12V jumper position, which bypasses the regulator circuit and is essentially the same as the L2 where only a MOSFET is used for switching. Yes, I do see the same as you reported and there is output at S0 (zero), just very minimal and my laser is off.

Agastar

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Re: Pin 11 PWM remains after image completes
« Reply #31 on: July 10, 2016, 10:35:57 AM »
Did you see that with the new ttl board attached directly to the diode?

Zax

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Re: Pin 11 PWM remains after image completes
« Reply #32 on: July 10, 2016, 01:13:38 PM »
(sorry for the long explanation)

No, but I now know what is going on.

In T2Laser the footer at the end of my G-Code generator sends:

M03 S0 (laser power 0)
M05 (laser disable)

Then, it moves back to the origin:

G00 X0 Y0 Fx

It is this move that causes the PWM to re-enable (must be something with the firmware, how they implemented the spindle control to allow changes on-the-fly)

If I end the program with an M2 or M30 this PWM signal stops but that also has a side effect of resetting Grbl and losing the home position, something I would prefer not to do (perhaps I could make this optional). This has been fixed by chamnit (Sonny Jeon) the current developer of Grbl in later versions of the master.

So back to your question, since the test G-Code I used for the laser power ramp up/down didn't have any moves after the laser power settings it did correctly shut off all PWM signal.

Agastar

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Re: Pin 11 PWM remains after image completes
« Reply #33 on: July 10, 2016, 01:48:46 PM »
Lol, I wondered if the move to home had something to do with it. Well, that explains why the GRBL 0.9i didn't do it. Mystery solved!

Agastar

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Re: Pin 11 PWM remains after image completes
« Reply #34 on: July 10, 2016, 03:02:46 PM »
Well, inbetween working on my laptop I was able to mess around with the laser a bit.

With my safety glasses on I put my multimeter on diode mode and checked the wires marked L+/L- and it read .855v one way and absolutely nothing the other way. With that I'm pretty sure those go to the pins on the laser diode.

The T+/T- pads don't appear to be connected to anything. :(

The fan pads (F+/F-) have continuity to the V+/V- pads so they are sharing the 12v source with the laser.

Zax

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Re: Pin 11 PWM remains after image completes
« Reply #35 on: July 10, 2016, 03:22:28 PM »
That will make it easier to hookup.

I will measure the voltage and current at full power so I can setup the current regulator board the same and see if it works. It probably won't be until next week as I have a business trip this week.

Were you hoping the T pins were already a TTL input? I did wonder if the board has the capability.

Agastar

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Re: Pin 11 PWM remains after image completes
« Reply #36 on: July 10, 2016, 03:48:44 PM »
Yeah I was hoping they were lol. I wasn't really surprised though lol.

kn4ud

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Re: Pin 11 PWM remains after image completes
« Reply #37 on: July 10, 2016, 04:01:04 PM »
It is going to be interesting to see what is on this board. I am not going to worry with it , from what I can tell the wires that go through the hole go to the diode. I am just going to unsolder them and run them to the board I have ordered and wire the fan to the board also. I have a 2.5w laser so at 12 volts it should draw around .2 amps (ohms law) this also figures to be around 57 to 58 ohms so I will most likely use some parallel .5 w resistors to get the 2.5w rating to test it first before connecting the laser. I will first start at say .1 amp and work up, checking to see how it does.
Question, does anyone have the adruino source code for the jtech firmware?
Allen

Zax

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Re: Pin 11 PWM remains after image completes
« Reply #38 on: July 10, 2016, 04:58:56 PM »
I just checked and those wires (grey and white, on L+/L-) are getting 12V, if they were going directly to the diode I would have expected half that or less.

I don't think J Tech Photonics have published the source code.

Agastar

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Re: Pin 11 PWM remains after image completes
« Reply #39 on: July 10, 2016, 05:28:24 PM »
Was that measures with the wires still soldered to the board?

Zax

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Re: Pin 11 PWM remains after image completes
« Reply #40 on: July 10, 2016, 06:45:49 PM »
Yes, with the laser running at 50% and full power. It appeared to be the PSU output, 12.8V.

Agastar

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Re: Pin 11 PWM remains after image completes
« Reply #41 on: July 10, 2016, 07:45:29 PM »
Sounds like the board only does current limiting then.

Zax

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Re: Pin 11 PWM remains after image completes
« Reply #42 on: July 11, 2016, 05:30:31 AM »
I'm not sure, if I move the jumper on my L1 board to "Adj." and set the output voltage to 5.5V the laser doesn't work.

If the module is just limiting current I would expect it to function, unless it's causing a significant voltage drop somewhere.

Agastar

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Re: Pin 11 PWM remains after image completes
« Reply #43 on: July 11, 2016, 06:24:49 AM »
If it were using a current regulation IC and that IC was designed to work in a range of 5-12v then it would work. However, since it isn't working at 5.5v, it might be a simple resistor and the value of that resistor was picked for a 12v source and might limit the current too much to work at 5.5.

If your multimeter has a diode setting you can find out what your diode's forward voltage is (assuming those wires are connected to the laser diode directly). Subtract that from your 5.5v and then calculate how much current is going through the diode.

Alternatively if you had the pot you could measure the resistance of it and the resistor in series and adjust until the laser came on. This would let you know the minimal current needed to turn it on at 12v.

Agastar

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Re: Pin 11 PWM remains after image completes
« Reply #44 on: July 11, 2016, 06:41:30 AM »
Not sure why I didn't notice this before when toning out the pads but I just found out there is nothing on the other side of the board. I just shined my laser pointer in the hole and you can see it is just traces. Also all the - pads have continuity to each other and same for the + pads to each other.