in the old days (the mid-late 2000s) 3D printer control electronics used to be built around an 8-bit microcontroller1 running at 10-12mhz doing everything. as printers got more sophisticated recently (a few years ago) new firmware features started hitting limits to storage and compute power, so the larger-scale hardware developers started designing boards around 32-bit microcontrollers2 which can run 50 times faster.
while this was happening, people got tired of having to run prints to their machines on thumb drives or microSD cards, so they started building control interfaces that sat on a single-board computer (like a raspberry pi) and talked directly to your printer over USB3, so you could copy prints to it over wi-fi; people started embellishing these interfaces with features like webcam streams, print-monitoring software, and software to automatically capture time-lapse videos. in this environment, work started on a new printer control stack called klipper, which completely hollows out the job of the control board to basically just be a fancy motor controller, and moves all of the compute-heavy parts onto the single-board computer you probably already have connected to your printer -- which is another half-dozen times faster than the fastest microcontrollers available, and has better peripherals (ethernet, wi-fi, a USB hub) and quality-of-life features (a graphics card to run nice displays). the single-board computers are fast enough that most of the stack can comfortably be written in python instead of embedded C, so the pace of development has been breakneck, and in the past year or so people have started shipping commercial printers with klipper built-in, instead of traditional firmware.
now it's come full circle, and bigtreetech4 just released the manta series, which is a control board with a bargain-basement 32-bit microcontroller (a 64mhz ARM cortex-M0+ with 144k of RAM, when their current mainstream board sports a 480mhz ARM cortex-M7 with a megabyte) but also an onboard socket for the raspberry pi compute module, raspberry pi's "deeply-embedded" single-board computer that you bolt directly onto another PCB.
I already had a compute module kicking around, and wanted a new control board for triangle man, so I decided to take a chance on the manta M8P. the compute module is the little green PCB peeking out from under that heatsink on the bottom right corner, it's got a HAT-compatible raspberry pi GPIO header next to it on the carrier board, and that's the linux terminal running on it on the little screen in the first picture.
truly a weird little guy.
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usually an atmel AVR -- because those are the microcontrollers used on the arduino microcontroller development boards, and some of the earliest affordable 3D printers were built around homebrew arduino breakouts
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mostly STmicroelectronics STM32s, which run basically every piece of embedded hardware on earth, though people have also been starting to build boards around the raspberry pi RP2040
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in a language called Gcode, the native tongue of 3D printing, originally adapted from CNC (computer numerical control) machining5
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one of the biggest hobbyist 3D printer hardware manufacturers, aka biqu, aka Shenzhen Big Tree Technology Co., Ltd.
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which, if you think about it, is basically the same process 3D printing is, except in CNC you cut into a work piece with a tool, and in 3D printing, you're cutting into free air with a little dribble of molten plastic
