Change to open source firmware

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey Derek, Neel @justneel,

@WaywardWoodworker

(I was never able to get it to build and install)

but what would be the reason that it did not work? If you look at the schematics, you can find the only very few differences (buildbotics/bbctrl-pcb vs. onefinitycnc-pcb). Of course the Onefinity Controller is a software and a hardware fork of the Buildbotics.com Controller. Both firmware and schematics, and the pcb too, you can clearly see where it comes from and find the differences. Obviously firmware it is based on Buildbotics 0.4.14.

Did you use the

• Buildbotics CNC Controller Development Guide to build it?

So regarding bbctrl-firmware, besides unpacking the files onto the Raspberry Pi OS system (“Stretch” of 2018 image) (https://buildbotics.com/upload/2018-05-15-raspbian-stretch-bbctrl.img.xz) that you put on a SD card in the Raspberry Pi 3B, the setup process includes uploading the AVR firmware to the AVR and to the ATTiny that measures the current on the AVR Mainboard. The Raspberry Pi 3B is the same in both hardwares.

Did you remember what the setup log said, specifically when it comes to uploading the AVR and ATTiny firmware?

@Aiph5u

The Raspberry Pi 3B that is inside the stock Onefinity Controller already has a 64-bit-capable CPU. The outdated Raspberry Pi OS from 2017 that runs on the Onefinity <=1.2.xx SD card images is an image of the 32-bit architecture “armhf” (ARM hard float), but switching to the 64-bit architecture “arm64” will work out of the box since the Raspberry Pi 3B is in fact made for it.

You can check this by taking an empty SD card and writing the most recent Raspberry Pi OS (64-bit) to it and boot it on the Raspberry Pi 3B.

I checked it, this recent ‘arm64’ image of course boots on the Onefinity Controller with its Raspberry Pi 3B. I did that when one buildbotics forum user reported that he was able to successfully build the Buildbotics-firmware sources on the Raspberry Pi 400 (Pi 4 based). I did not yet try to build ‘bbctrl-firmware’ on the Onefinity’s Raspberry Pi 3B though, but thought of trying it, since like Neel @justneel, I would prefer to contribute to the upstream project and would avoid to buy a separate controller.

@WaywardWoodworker

and it may/will brick the controller if you try it

I doubt you could brick it permanently as long as you are able upload the AVR firmware to the AVR and to the ATTiny.

@Aiph5u

The Raspberry Pi exchanges data with the AVR ATXMEGA192A3U (datasheet) only via I²C Bus (SDA/GPIO2 (pin 3) and SDC/GPIO3 (pin 5)) and over the serial interface (TXD/GPIO14 (pin 8), RXD/GPIO15 (pin 10) and CTS/GPIO16 (pin 36 of Raspberry Pi GPIO header)).

The latter is how the CNC Controller part works, by the bbserial.ko kernel module (See also Deep dive: Hacking the 8-bit AVR – By Joseph Coffland).

@Aiph5u

Note that there is also a TinyAVR microcontroller on the board which measures and controls current that is connected to the same I²2 bus than the main AVR.

What is missing on the Onefinity fork, is the small LCD on the box. It is on the same sda/sdc bus with two wires. So I would remove the code that drives it.

Buildbotics Controller (front)

EDIT: onefinity-firmware/src/avr/src/lcd.c and lcd.h exist and seem not to do any harm, although Onefinity lacks the LCD on the box.

Meanwell 36 V power supply is internal on the Onefinity, external on the Buildbotics. One difference on the pcb is that Load1, Load2, Probe and Laser are additionally made available as Molex sockets on the Onefinity Controller, while on Buildbotics you only get them via the 25-pin I/O port. A good thing on the recent Buildbotics version is the 15-pin Auxiliary Port that allows connection of external stepper drivers so you can use other things like closed-loop steppers or servos. However that is just a port, not a circuit change.

Buildbotics CNC Controller (back)

Onefinity CNC Controller (back)