Pin 11 PWM remains after image completes

[beikeland]

Curious, how does the "weak" button function after the upgrade? Hopefully I won't be using the original controller for long, CNC shield or RAMPS depending on success with building a Z axis, will be installed.

[Agastar]

The weak button will not work with this upgrade but that's ok because the software needed to take advantage of PWM/TTL can provide the weak laser functionality.

We have tossed around the idea of building a board with a weak laser button that will work with this driver but that may be a ways off.

[ggallant571]

Speaking of board with TTL weak laser. Attached is my first cut at such a board with provision for Nano or Mini2560 board. Artwork to match these schematics is also ready.

[Agastar]

Oh Nice! That's looking really good! You are the MAN!

Well, we may have a board with the weak button sooner than I thought.

[ggallant571]

The Nano to Mini pin mapping does not match that being prototyped today. Tomorrow I will investigate if rotating the Mini 180 degrees makes the current mapping possible (didn't think about that till just now). My personal goal for the board is to investigate driving the 3 stepper motors via hardware PWM. To that end I, or anyone else interested, needs to verify that the 4 PWM channels are completely independent. Not like the 328 with 2 channels per timer.

Attached in png of artwork.


   

[Agastar]

I thought they were but I'll have to refresh my memory.

[Lob0426]

That may work as the Analog and Digital sides are reversed between the Mini-Mega and the Nano.

A couple of hints. Do not carry the either of the coolant pins through, we do not need them That's pins A3 and A4 on the Nano and D8, D9 on the Mega if I remember correctly. We do not use anywhere near all the pins on the Mega. So could you get it to work better by only having the pins you need on the board?

I suggest that you not bother with the homing pins on the Nano I think most people will use Benbox on the Nano. And most do not have homing anyway. So route the limits from the Mini-Mega straight to the limit headers. Just a suggestion. And Vin does not need to be connected.


The Mini-Mega boards come with no pins installed. Most of the connected pins are on the Digital side of the board. There only about six pins used on the Analog/upper # digital pin side. And only one GND on the end opposite the USB. So we only need these and enough pins to keep the board solid.

That should reduce the number of traces

No the PWM's are still Siamese'd on the Mega's. D7, the Laser PWM, is not on any of the stepper PWM's that I know of. So you should be able change it's PWM without affecting the steppers.

[beikeland]

The weak button will not work with this upgrade but that's ok because the software needed to take advantage of PWM/TTL can provide the weak laser functionality.

I expected it would not work, but let me re-phrase. Does it faill 'safe', or will a new driver hooked up the the original laser output enable the laser at full power when the weak button is pressed, or will the lower voltage provided simply not power the laser at all?

I expect to be running cnc sheild or ramps before changing the driver in any case, so its mostly a curious question.

[beikeland]

The first picture is me testing the power with a G2 lens.

OT: Hmm, would that power meter enable you to measure how effective the supplied green goggles are, if you can find the time?

[Agastar]

I expected it would not work, but let me re-phrase. Does it faill 'safe', or will a new driver hooked up the the original laser output enable the laser at full power when the weak button is pressed, or will the lower voltage provided simply not power the laser at all?

I expect to be running cnc sheild or ramps before changing the driver in any case, so its mostly a curious question.

That is a good question and thanks for asking. The driver would come on at full power when the weak button is pushed in. To avoid this, you would need to connect to the jumper under the arduino for the 5v PWM signal or not use the weak button.

OT: Hmm, would that power meter enable you to measure how effective the supplied green goggles are, if you can find the time?

That's not a bad idea. I would need to find the right beam size and the right power setting to to get a before and after reading without melting the plastic. From there you could calculate the percent attenuation.

[ggallant571]

Just route the WEAK switch to a digital input and let the firmware enable the laser at the absolute lowest power level.

[Agastar]

Just route the WEAK switch to a digital input and let the firmware enable the laser at the absolute lowest power level.

We might need to make a tutorial on how to do that with pictures of the process.

[beikeland]

I read a lot of (potentially?) FUD about ESD with UV/blue laser diodes, and as I live in near prehistoric block where there are no grounded outlets, my only option is to clamp a ground wire to the water supply and drain pipes, so not ideal for electronics. Luckily I only have about 5m to the pipes from my desk, and ran 2.5mm^2 ground wire to a clamp.

But I'm still a bit weary about digging out the diode to do the TTL upgrade. Would it make any difference if I shorted out the diode while working on it? I read people putting resistors, caps, zeners and TVS across the diode to help against ESD.

But from my point of view the diode is either connected to the driver, which should provide enough protection for normal usage, or disconnected. In the latter case a dead short sounds more effective than even the fanciest Lasorb or discretes? Or am I just over simplifying things now?

[beikeland]

Link to quoted post, with image: http://benboxlaser.us/index.php/topic,381.msg4242.html#msg4242

I found this image of what appears to be the board that most of us have ordered. This has a little more detail .

I just received this board, which i ordered at the same time as the machine, along with a lower power laser module. Looks like the two holes on the board align with the two of the 4 holes above the stepper motor on the back side of the X carriage. Just an FYI if that was news. Still working on disassemble my low power laser to install the TTL driver though, it sure won't come apart by accident

If it works well enough then >$4 and with mounting holes that fit the machine its a pretty good deal, but I guess I'll see how well it works over the weekend.

[kn4ud]

LOL, they are fun to take apart. You can't get it apart without destroying the OEM circuit board in the heat sink, or at least I could not.