Author Topic: Identify microcontroller for reverse engineering cheap robot servo  (Read 1784 times)

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Offline ITman496

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Hello!  I want to make a cool hexapod robot, and I found these actually pretty decent, but more importantly CHEAP serial bus servos on amazon.  They are Lewansoul LX-16A servos.

http://www.lewansoul.com/product/detail-146.html

They have all metal gears, a continuous and angle mode, decent torque at 17kg/cm at 7.4V, you can daisychain them on a serial bus like dynamixel servos and have up to 253 of them.  I think it uses the same protocol as them, actually.  You can even read motor temperature and current angle back over the serial link!  All this for 14.99USD!

There are a few downsides, though.  The motor is apparently a little overvolted, so if you run it at 7.4 and at max load for long, you're going to fry it. But its a common size, and replacements of a suitable voltage rating can be had for only a dollar or two.  I don't plan on maxing them out too badly, and I will run them at a little less voltage.

Something really nice is the 3D cad reference they come with appears to be the same one they use to make the servo, as it contains all the gears and internal shafts, the pcb and its mounts, the potentiometer, motor, bearings.. etc.  I've never seen that provided as a cad ref before.

This brings me to what I want to do.  I want to try to see if its possible to add some features to this little servo, like PID control. Right now it appears to have a very basic control loop, with some overshoot if you move fast.

I can not identify the microcontroller, and before I design my own drop in replacement PCB, I'd love to see if it was possible to just reflash the firmware on board.   I have pulled this number from the top of the cpu, and this is what it looks like:

HL 004
642GB
2634B071
ARM

So does anyone know where I can start trying to do this?  I admit I have very little experience with microcontrollers outside of the arduino compatible atmega realm..
« Last Edit: February 10, 2018, 02:26:45 am by ITman496 »
KD2CHS
 

Offline amyk

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Re: Identify microcontroller for reverse engineering cheap robot servo
« Reply #1 on: February 10, 2018, 05:57:33 am »
Quick Google shows it's likely to be a Nuvoton MINI54ZDE. Appropriately enough, also found in drone control boards.
 
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Offline ITman496

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Re: Identify microcontroller for reverse engineering cheap robot servo
« Reply #2 on: February 10, 2018, 08:47:11 am »
Interesting! It appears that this might be the same Mini54 chip that the older version of the Teensy series used?

A quick google does not show any native support for this chip with the Arduino ecosystem so in terms of reprogramming this with my current skill set, I may be out of luck.
KD2CHS
 

Offline neutronstar

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Re: Identify microcontroller for reverse engineering cheap robot servo
« Reply #3 on: November 16, 2021, 09:00:43 am »
Hey, did you ever get a PID control loop working with these motors? (inside the motor or outside) I'm working on a project with these same ones and PID control would be awesome!
 


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