Cohesion3D board pinout


I am trying to do some unconventional things with my laser and am not familiar with the Cohesion3D board yet. Is there a pinout or datasheet for the board layout? Something similar to maybe?

Thanks in advance.


Hi Trent,

Here is a diagram showing the pins used on the LaserBoard:

If there is something specific you would like to do, please let us know.


Thanks for the reply.

I am really looking for a list or a diagram of where each of the pins (from the ARM mcu) are broken out onto the board. I ask this as I am using the board in an unusual way and need to make the best decision of what/where to tap into.

I need to have an input pin that can be triggered with a digital signal (TTL or CMOS, high or low, I have made the interface board flexible as to what it outputs) that will either immediately stop or, if possible, skip to the next cutting bank.

Not sure if the details matter to you or not, but I am trying to trim resistors with a CO2 laser I built (cartesian K40 design using Cohesion3D controller). The way I have planned to accomplish this is as follows;

My interface board monitors the output of an LCR meter (HP4275 that will constantly read the resistance of a given part) then my board can output a digital signal (TTL 1, TTL 0, CMOS 1, or CMOS 0) when the reading reaches one of the values that are set on the interface board. I then want to modify smoothieware to perform an action (I’ll likely begin with stopping, {and then attempt to cause it to skip to the next instruction bank after I have gotten the first part working}) when it receives that signal on the gpio pin I choose.

Thanks for your time and advice.
Trent - KM4YTU

Hi Trent,

This sounds like an interesting project to undertake! At this time, no such thing exists for the LaserBoard at the level you are looking for.

You can use one of the unused endstop pins as an input. They are spelled out in the config file and correspond to the name on the board’s silkscreen labeling. These pins are buffered.

It is also possible to access direct MCU GPIO pins via the “ethernet expansion” header. However, these are not protected in any manner, so we recommend trying the endstop pins first.


Thank you once again for your reply.

I will use the expansion header intended for ethernet and incorporate that into the next revision of my interface board. If there is interest I would be glad to make it more flexible in the next rev and to release it open source for others, although I’m afraid that my modified smoothieware is likely to be a butchered mess as my programming ability is quite lacking.

As an aside, I was looking over the board last night and noticed that two test points on the back of the board (above the silkscreen “ENDSTOPS (V+GndSig)”) appear to be directly connected to two mcu pins. I assume that these were used for QC during manufacture. Do you know if these are indeed directly wired and also do you know if they are active for any function in the shipped firmware…just trying to cover my bases before I start tearing into it.

Best regards,
Trent - KM4YTU

Those are 2 ADC pins that I was debating breaking out on the board - this is the extent to which they happened. They may or may not be tied to the typical thermistor RC circuit that you’d see on a 3D Printer board (my roots were originally in 3D Printers and that’s what we made before the laser stuff stuck, all those several years ago)


Thanks for the prompt reply.

Okay, it’s great to know that a pair of analog pins are available if needed.

From memory do you recall their resolution? From looking over the NXP datasheet I seem to think I saw a 12bit ADC, does that sound familiar? I won’t be using it right now, but would like to be familiar with the capabilities in case I need them in the future. Other than that, that is all I needed to know at the moment. Thank you again for your response.

Trent - KM4YTU

Not sure, I think that our laser PWM output is 10 bit, so different ballgame, similar ballpark though.

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