UMO 1.5.7 PCB, LED / 19V DC output - PWM? ON / OFF?

[martin-bienz 36]

Hi Guys,

I was really looking for this and I could not find a concrete anwser, so question for you UMO owners out there .

The specifications of the 1.5.7 board I could find here: http://reprap.org/wiki/Ultimaker's_v1.5.7_PCB describe the specifications and include this feature:

- A PWM output with power for LED arrays and other lighting

Now, I allways assumed this is the port labeld LED Port / 19DVC on 1.5.7, would make sense right? Picture of the output on my board that I connected my LEDs to, just to be sure we are talking about the same thing / output:

It works, they seem to be default ON / max PWM.

Someone knows if this is actually PWMable and / or controllable with GCODE?

Thanks

Martin

[martin-bienz 36]

No UMO owners with LEDs?

Are there schematics / documentation for the board so I could try to figure it out myself?

[anon4321 16]

Unfortunately, as near as I can remember, that WIKI is incorrect. I don't believe the LED connector can be PWM'ed. I believe it is hardwired to 19V.

You'll need EagleCAD to open the files but they are here:

https://github.com/Ultimaker/UltimakerOriginal/tree/master/1090_Arduino_Mega_Ultimaker_Shield_1.5.7

If my memory is correct, you might be able to run the LEDs off the second heater output if you don't have a dual extruder output. But you would need LEDs that can run on 19V. And you might need to tweak the firmware.

[martin-bienz 36]

@anon4321, thank you very much! That would confirm my fears . I will look at the eagle files tomorrow. Maybe I will then go for exp3, pin13 and an additional transistor (my leds run at 19v, no problem) to turn them on and off (pwm). I will let you know if you are interested.

[aggertroll 12]

@anon4321, thank you very much! That would confirm my fears . I will look at the eagle files tomorrow. Maybe I will then go for exp3, pin13 and an additional transistor (my leds run at 19v, no problem) to turn them on and off (pwm). I will let you know if you are interested.

I would definitely be interested! I have my UMO (heated bed in the mail (I hope)) illuminated by 3 IKEA Dioder LED strips. They are on a completely separate power supply since I don't know enough about electronics to use options on the board. Solid advice on hooking them up to the board would be highly appreciated - pwm is secondary. Thanks.

Edited January 10, 2016 by Guest

[martin-bienz 36]

Ahhh... no eagle installed. okay. I just assume it's a fixed 19V DV source and use P13, EXP3 to create a small pwm circuit with an npn transiistor. my leds, 3 x dioder, I seem to remember are in series 18V which is just fine. They draw around 0.4 Amps (400 mA) so with a standard npn BC337 or so, this should be doable. I guess... will try.

[martin-bienz 36]

okay. I have it running. I have no clue why, but P13 did not do anything ... at all. So I took P12, that is doing ON 5V and OFF just fine. So with P12, I can now switch a BC337 on that switches the 19 V DC output on and voila, the LEDs light up.

That means, I can now turn on via M42 P12 S255 and turn OFF by sending M42 P12 S0. Works just fine.

Maybe the BC337 is a bit on the lower end, could be higher? The LEDs draw only .45 A and my datasheet tells me that my BC337 is good up to 0.8 Ic... it gets warm, hot. let's see how it goes.

More info upon request.

[anon4321 16]

I installed Eagle and checked. The LEDs output is just the 19V supply. There is nothing controlling it.

If I were you, I would just duplicate the fan controller portion of the shield. It's a BD679 darlington pair with a 1k current limiting resistor for the base. Good for a couple amps.

Buy a couple extra BD679 in as backups for the one on the shield. Then you have a spare should the fan been shorted.

The marlin firmware seems to define a LED control pin as pin 13. If you figure out what pin that maps to on the shield and use it for the LED drive then I think you will get GCODE control of the LEDs without changing the firmware. Although I'm making a lot of assumptions.

See line 1319 here https://github.com/Ultimaker/Marlin/blob/Marlin_v1/Marlin/pins.h

This is the fan control portion of the shield:

Looks like pin 13 is in the group near heated bed output

Good luck.

[anon4321 16]

sorry my reply was a little late. So pin 13 didn't work? strange...

[anon4321 16]

It's possible that the PWM frequency is too high and your transistor isn't switching on and off fast enough. So the transistor might be operating in the linear region longer then it should and dissipating a lot of power.

[Dim3nsioneer 557]

I think @gr5 might be able to provide some help here as he did some PWM work in the Ultimaker2 version of Marlin for the heated bed of the UM2 Go.

[martin-bienz 36]

@anon4321, thank you!

hmm... I don't think the PWM frequency is too high, I think (am not sure) I used those transistors before to drive som LEDs for another arduino project. But hey, I will try with BD679 if I get some. For now, on and off is just fine on PIN12. I will need to look at the schematics again...

@Dim3nsioneer, great thanks, but is the UM2 Go not equiped with a "new" board? I thought they allready have a powered PWM output for LEDs? Or did @gr5 do seomthing custom with the analaog PINS?

I have also created my own PWM board for the heated bed, works quite well. I will need to look at it once I have some more time...

[martin-bienz 36]

short update... it works just fine as described on PIN12 (without PWM). I had it on for more than 24 h and the BC337 transistor is still working . I put the small board just under one of my electornics cooling fans, so I guess it's fine.

Still wondering why my P13 is dead...

Next step is probably connecting a small dc/dc voltage regulator to the print cooling fan output (19V to 12V) in order to be able to install super silent and efficient 12 V (or maybe even 2 small 5 V) fans in paralel... for better print cooling. UMO hacking is still cool.

Edited January 13, 2016 by Guest
small corrections, typos