Unitree GO-M8018-6 Motor Reverse Engineering

May 23, 2026 by Maya Posch 10 Comments

People seem to be rather into the Unitree Go2 quadruped robot, if only for the low price tag. But perhaps more interesting are the motors that propel it — they appear to be similar to the Go1’s GO-M8010-6 motors that Unitree also sells, with [Thomas Flayols] currently working on reverse-engineering its proprietary driver using the publicly available documentation for that motor and some reverse-engineering.

These motors are an assembly that includes a reducer, magnetic encoder, 3-phase inverter, current sensing, an RS-485 bus and a Cortex-M0-based CMS32M57xx MCU, all in a very capable package intended for robotics applications where a compact actuator is needed.

The first step of reverse-engineering involved the physical PCB, made all the more difficult as Unitree was so kind as to remove all markings on the ICs. Fortunately using an X-ray machine and some sleuthing it was possible to deduce the MCU and other components. Following this SWD/OpenOCD access to the MCU could be established and the firmware key extracted from the bootloader SRAM.

Although the firmware was encrypted, a locally recovered key was found to decrypt it. This allowed for an initial custom firmware to be developed, which [Thomas] hopes to develop into a fully featured open source firmware. Doing so would obviously open these motors to a larger audience outside of Unitree’s ecosystem, as they are pretty good value for what they offer mechanically.

It might give the associated Go2 robot a new life too considering the serious malware accusations and security issues pertaining to its firmware.

DIY Linear Tubular Motor Does Precise Slides

March 31, 2025 by Donald Papp 25 Comments

We’ve seen plenty of motor projects, but [Jeremy]’s DIY Tubular Linear Motor is a really neat variety of stepper motor in a format we certainly don’t see every day. It started as a design experiment in making a DIY reduced noise, gearless actuator and you can see the result here.

Here’s how it works: the cylindrical section contains permanent magnets, and it slides back and forth through the center of a row of coils depending on how those coils are energized. In a way, it’s what one would get by unrolling a typical rotary stepper motor. The result is a gearless (and very quiet) linear actuator that controls like a stepper motor.

While a tubular linear motor is at its heart a pretty straightforward concept, [Jeremy] found very little information on how to actually go about making one from scratch. [Jeremy] acknowledges he’s no expert when it comes to motor design or assembly, but he didn’t let that stop him from iterating on the concept (which included figuring out optimal coil design and magnet spacing and orientation) until he was satisfied. We love to see this kind of learning process centered around exploring an idea.

We’ve seen DIY linear motors embedded in PCBs and even seen them pressed into service as model train tracks, but this is the first time we can recall seeing a tubular format.

Watch it in action in the short video embedded below, and dive into the project log that describes how it works for added detail.

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Driving A Motor With An Audio Amp Chip

September 18, 2023 by Al Williams 25 Comments

[InazumaDenki] wanted to answer the question: can you drive a motor with an audio amplifier chip? The answer, of course, is yes. The TDA7052 has a single input, and a bridge output meant to drive a speaker differentially. It should work if the motor doesn’t present more of a load than a speaker.

The plan was to use a resistive divider to provide several discrete voltages to the input. At precisely the half-way mark, there should be no voltage across the load. Altering the input to go higher than halfway should make the motor turn one way, and making it go lower should turn the motor the other way. As you can see in the video below, it does work, although it may not be ideal for this application.

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Arduino Takes Control Of Dead Business Card Cutter

September 10, 2020 by Tom Nardi 13 Comments

It’s a common enough situation, that when an older piece of equipment dies, and nobody wants to spend the money to repair it. Why fix the old one, when the newer version with all the latest bells and whistles isn’t much more expensive? We all understand the decision from a business standpoint, but as hackers, it always feels a bit wrong.

Which is exactly why [tommycoolman] decided to rebuild the office’s recently deceased Duplo CC-330 heavy duty business card cutter. It sounds like nobody really knows what happened to the machine in the first place, but since the majority of the internals were cooked, some kind of power surge seems likely. Whatever the reason, almost none of the original electronics were reused. From the buttons on the front panel to the motor drivers, everything has been implemented from scratch.

An Arduino Mega 2560 clone is used to control four TB6600 stepper motor drivers, with a common OLED display module installed where the original display went. The keypad next to the screen has been replaced with 10 arcade-style buttons soldered to a scrap of perfboard, though in the end [tommycoolman] covers them with a very professional looking printed vinyl sheet. There’s also a 24 V power supply onboard, with the expected assortment of step up and step down converters necessary to feed the various electronics their intended voltages.

In the end, [tommycoolman] estimates it took about $200 and 30 hours of work to get the card cutter up and running again. The argument could be made that the value of his time needs to be factored into the repair bill as well, but even still, it sounds like a bargain to us; these machines have a four-figure price tag on them when new.

Stories like this one are important reminders of the all wondrous things you can find hiding in the trash. Any time a machine like this can be rescued from the junkyard, it’s an accomplishment worthy of praise in our book.

Robotics Controller For The Pi Boasts An Impressive Feature List

November 5, 2019 by Donald Papp 4 Comments

[Michael Horne] recently shared his thoughts on the RedBoard+, a motor controller board for the Raspberry Pi aimed at robotic applications. His short version for busy people is: if you’re at all into robotics, get one because it’s fantastic.

At heart the RedBoard+ is a motor controller, but it’s packed with I/O and features that set it above the usual fare. It can drive two DC motors and up to twelve servos, but what is extra useful is the wide input range of 7-24 V and its ability to power and control the underlying Raspberry Pi. A user-programmable button defaults to either doing a reboot or safe shutdown, depending on how long the button is held. Another neat feature is the ability to blink out the IP address of the Pi using the onboard RGB LED, which is always handy in a pinch.

The RedBoard+ has a GitHub repository which provides a variety of test scripts and an easy to use library, as well as a variety of hookup guides and quickstart guides. There’s even a pre-configured SD image for those who prefer to simply dive in.

A brief demo video showing the board in operation is embedded below. If you’re interested in one, Creator [Neil] of RedRobotics has made it available for sale on Tindie.

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Arduino Drives Seventeen Stepper Motors, Carefully

April 9, 2019 by Tom Nardi 27 Comments

It’s fair to say that building electronic gadgets is easier now than it ever has been in the past. With low-cost modular components, there’s often just a couple dozen lines of code and a few jumper wires standing between your idea and a functioning prototype. Driving stepper motors is a perfect example: you can grab a cheap controller board, hook it up to a microcontroller, and the rest is essentially just software. But recently [mechatronicsguy] wondered if even that was more hardware than was technically necessary to get the job done.

It’s not that he was intentionally looking to make things more complicated for himself, of course. His rationale was entirely economic; if you’re looking to drive a dozen or more stepper motors, even the “cheap” controllers can add up. So he started to wonder if he could skip the controller entirely and connect the stepper motor directly to the digital pins of an Arduino. Generally speaking this is a bad idea, but if you’re careful and are willing to take the risk, [mechatronicsguy] is living proof it’s possible

So what’s the trick to running a whopping seventeen individual stepper motors directly from the digital pins of an Arduino Mega? Well, to start with you’re not going to be running the beefy NEMA 17 motors like you might find in a 3D printer. [mechatronicsguy] is using the diminutive (and dirt cheap) 28BYJ-48, a light duty stepper used in many consumer products. Even with this relatively tiny motor, you need to crack open the case and cut a trace on the PCB to switch it from unipolar to bipolar.

Beyond that, you need to be careful. [mechatronicsguy] reports he’s had success running as many as ten of them at once, but realistically the fewer operating simultaneously the better. This is actually made easier due to the relatively poor specs of the 28BYJ-48 motor; its huge eleven degree step size means its not really susceptible to the same kind of slippage you’d get on a NEMA 17 when powered down. This means you can cut power to all but the actively moving motor and be fairly sure they’ll all stay where you left them.

With as popular as the 28BYJ-48 stepper is, there are several projects this “quick and dirty” method of interfacing could potentially work with. This small “barn door” star tracker is an obvious example, but we’ve also seen some very nice robotic arms built with these low-cost motors which could benefit from the technique.

New Part Day: ST’s New 3D Printer Motor Driver

October 29, 2018 by Brian Benchoff 21 Comments

ST has released a new evaluation board for a stepper motor driver. It’ll plug right into your 3D printer, and if you’re looking for a chip to build a cheap 3D printer controller board around, this might be the one.

We’ve come a long way in the field of stepper motor drivers in just a few short years. The first popular driver for RepRap electronics was ‘the Pololu’, a stepper motor carrier board using Allegro’s A4988 driver. If you had a big heat sink, this driver could deliver 2 A per coil, operated between 8 and 35 V, and had microstep resolution down to 1/16th. Was it the best stepper driver around? No, but it was cheap, it was everywhere, and RAMPS, the popular RepRap control electronics picked up on its pinout and accidentally created a standard. The DRV8825 motor driver from TI followed next, with microstepping down to 1/32nd, a little more current per coil, and arguably a better thermal design.

Then the wave of Trinamic drivers happened. The Trinamic TMC2100 was a silent stepper motor driver when running a motor at medium or low speeds. With this driver, you could run a motor more efficiently, which means the motor doesn’t get as hot. There are diagnostics via SPI. Tom liked it, and now in every Prusa i3, you’ll find a bunch of Trinamic drivers.

ST’s new offering, the STSPIN820, doesn’t have the fancy-schmancy features the Trinamic driver does, but the chip itself is fantastically cheap, at about 1/5th the price of a Trinamic driver. As far as feature set, you should probably look at this new chip as an upgrade to the A4988, with much higher microstepping and slightly higher current handling.

If you’d like to experiment with the evaluation module, you can grab one from an ST distributor; at the time of this writing, there were seventeen of these modules available worldwide. If you’d just like to play with the STSPIN820 motor driver chip, ten thousand are available between Mouser and Digikey, starting at $2.97 in quantity one. If someone could tell electronics manufacturers to build more than a dozen evaluation boards at a time, that would be great.