Toy Motor Controller Update: PCB Revision, Menu, Bootloader and Memory Card Support

March 31, 2024, 5:35 a.m. Electronics ilo lawa nasa

It's been more than a year since I've posted any update of this project on this blog. If you know me personally, you should probably have heard that this project has been on-going because I do talk about this project online from time to time. It just happened that I've been too busy to update this blog. Now that I've finally got the time to document the latest progress over these months, as well as the planned future development of this project.

Hardware Revision 3

Photo of Toy Motor Controller Hardware Revision 3

I've revised the hardware. The new hardware update includes:

A further revision is pending, which mainly focus on fixing hardware bugs and optimizing the design for small scale production. The pending revision doesn't change the feature set above.

Firmware Development

I've split the firmware into two parts, the bootloader and the app. The bootloader is used for performing firmware upgrade for the app. The app is where pretty much everything happens. The idea is to let the user develop their own custom app to be loaded into this toy motor controller.

The app upgrade file format is a dumb .BIN file. Basically it's just a binary stream to be self-flashed to the app region of the flash. The bootloader would flash as many pages as the size of the .BIN file. The development of the bootloader has just been completed.

The app development is still on-going. The user interface prototype is done with working menu and display. The UART protocol is also working. However, it's currently pretty difficult to develop plugin for this toy motor controller so I need to find a way to make it easier to perform plugin development. I foresee that I'd need to change quite a bit of the codebase for that.

On the app driver side, it's done and tested working except for the external memory card part. However, the existing code that initialize the peripheral is very inefficient (thanks to the auto-generated code of STM32CubeMX). I plan to make it more efficient somehow.

As for external memory card support for the app, I need to implement that. I'm mainly interested in data logging, config import/export and firmware dumping.

Production Plan

I found that it's too much work to manually solder the units for small scale production, especially for SMD soldering, I need to wear the gloves, take out the equipment and material, do the job and perform clean up, which's rather time-consuming. Therefore, I've decided that manual SMD soldering is to be done on only a unit or two for prototyping purpose. After the prototype is verified to work correctly, I'll at least outsource the SMD soldering for small scale production. For the parts with larger pitch, I could still solder that on my own if it isn't economical to outsource in small volume.

In the next revision, I'm gonna put all SMD parts on one side, and parts that can be hand-soldered on the other side.


As this is a hobbyist project, making profit is not and will never be the primary objective, just like other electronic projects that I work on. (To whoever proposing commercializing this project, particularly a certain close internet friend of mine coming from CIS, fuck you! As if I'd want to keep hustling off the clock! :P)

The main objective of this project is for me to learn and to share the tech that might be useful for others. There's no solid release schedule for this project. Tentatively I hope that I can get the first batch out by the end of this year, probably in a scale of <20 units. I'll make another blogpost of this project again when the time comes.

If I can complete this project, the firmware will be released under an FOSS license.