Maslow 4 - available IO (GPIO, I2C, SDIO, Tx/Rx, PWM, etc.)

I’ve not seen the Maslow 4 schematic yet. Q: What IO is drawn out to through-holes for pin headers - I2C, SDIO, 3v3 TX/RX, GPIO, PWM, etc. ? These IO will be important for the community to enhance the firmware & their Maslow’s features.

I2C (with power)

  • allows for an 2x16 LCD or OLED screen 32x128 or 64x128 to glance at it for progress without looking at the WebUI
  • allows for sensors (temperature, motion) and other digital IO to be added to

3v3 Tx/Rx - all development work needs a native serial console

SDIO - this will allow folks to add their own SD Card breakout boards for additional storage & features.

  • for possible user mods
  • logging
  • various file storage

Some GPIO, kind of necessary for things such as having an I2C sensor needing to switch/latch on-off a relay or optoisolator – such as sensing & turning a cooling fan on.

PWM - I suspect those are all used up by the motor controller.

I know it’s late in the game to add parts, it also adds cost for features some folks won’t use. Do not add them as it will create delays.

But please consider adding at least adding the traces & through-holes to allow others to enhance their Maslow 4’s. The headers do not even need to be in straight line like on an SBC - spread them around to where it’s convenient & workable for the current board layout.

Thanks for your consideration. Cheers.
(I’ll post a short version referencing this post in my KS Pledge).

There is already an AUX connector on the board…It’s a JST-XH connector, but those have the same pin spacing as a header if you want to connect that way, they’re just a little more secure…right now it has 3.3v, GND, Serial TX/RX and I believe we will have two extra GPIO pins, but it’s possible that there will be four. I will be sure to break out any unused GPIO for expansion.

I agree that it’s super important to have as many as possible.

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Hi Bar,

Something else just crossed my mind – more spaghetti ideas to see what sticks. Please don’t waste your time if it has a dead end or a major time sink.

I just remembered that ESP32 has built-in CAN Bus two-wire (as mentioned here on this Reddit post).

Would it be possible to break those out as well? IIRC, some other CNC machines also use CAN Bus - just like some Klipper 3D printers. Having CAN through-holes broken out would likely benefit the future use-case of Modders.

Thanks again for your consideration.

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Hi bar,
Maybe it’s confuse idea and too late.

I found lots of CNC product usually have laser add on so I think Maslow CNC also could be switch to laser engravers by connect laser module.

Does any method or plan could add HAT for laser module included PWM , 12 voltage and other necessary components?

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a laser on an open frame like the maslow is fairly risky. people have done it in
the past, but I think they did it for just cutting (due to the low speed of the

I don’t know Bar’s plans, but I would not expect it.

David Lang

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I made sure that the controller board will support it, but @dlang is right that I think it’s a little too dangerous so I probably won’t make an official one. I am 100% certain that there will be Maslow style laser cutters available soon.

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Anyone considering mounting a laser on their Maslow should read Phil “Certified Laser Safety Officer” B’s rant on the Cubiio laser.


I think that Cubiio might be one of the first to bring one to market. They do lasers AND have a CNC very similar to Maslow4 so they’re in the running for sure. I think that there is probably a way to do it safely, but it’s not on my agenda to try

I agree the laser cutting needs more safety protection than CNC.

I respect your plan and decision.

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Would it be possible to get the pinout and mapping for the GPIO? I assume it is one or both of these connectors?


Pin to pin spacing on JST-XH is 2.5 mm, as opposed to 2.54 mm (.1 in) for a standard header. For two pins you might make it work, but not for three or more pins.

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Absolutely. The pin out on those looks like this:

And on the ESP32 side we have:

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To make it a little easier to process, here is bar’s pinout as it looks on the board.