Even better low cost speed controllers

For some reason I have a passion for cheap speed controllers. In searching the web I noticed there are a bunch of affordable and pretty high quality brushless ESCs. I went scouring the web for firmware to convert the brushless ESCs to to a brushed, but came up empty handed. All brushless ESCs contain the necessary hardware to perform the task of being a brushed ESCs but finding firmware to convert the ESC for this purpose is super hard to come by.

My guess as to why this is, is that the leading firmware options for brushless ESCs are all written in assembly. This is done to maximize the performance of the very tiny micro controller that runs on the ESC. Unfortunately, assembly code is very low level and hard to modify. Seeing as the task of controlling a brushed motor is much simpler than controlling a brushless one, I felt there was room to write a branch of controller firmware that was entirely in C and could be easily modified.

Introducing MegaBrush, a simple C based firmware for SimonK and BLHeli ESCs that allows for high performance control of brushed motors. MegaBrush includes programmable RC Max and Min values as well as a reliable deadband at the center of the stick. MegaBrush also includes safety features such as failsafe power off and no-start out of deadband.

MegaBrush is very easy to install for ESCs running the SimonK or BLHeli bootloader. You can program the ESC using any popular ESC programming tool. In addition you can always easily flash back to SimonK or BLHeli at any time.

The primary ESC I developed this firmware for is the KingKong 12A Opto. This speed controller can be purchased from HobbyKing for about 5 dollars. This controller comes pre-loaded with the SimonK Bootloader and can be easily flashed using the the standard BLHeli flashing app.

I am working to add support for other ESCs as well as improve the overall featureset of MegaBrush.

You can download MegaBrush here: https://github.com/amcchord/MegaBrush

Low Cost Brushed Speed Controllers

Finding a good cheap speed controller for brushed motors can be hard, especially for small robots. I have been on the search for a good supply of low cost small speed controllers for the past few months and I think I have found a solution for under 7 dollars.

There are a large number of small brushed controllers made for TZ4 type RC cars. These controllers are sold under a bunch of names, but tend to be all the same. The problem is these controllers run in a mode setup for RC cars known as Forward/Brake/Reverse. To switch from forward to reverse you need to apply reverse twice. While this might be fine for an RC car, this doesn't work well for tank style (skid) steering robots. Some models of these controllers can be purchased at the links below. 

It turns out there is a way to change the mode on the speed controller to a more robot friendly Forward/Reverse. It requires simply soldering a specific jumper on the board. The image below depicts the jumper that should be closed. It is the jumper located between the power switch and servo input. There is a small arrow on the board pointing to the jumper. 

I have done some testing with these ESCs and they appear to perform well above their rated spec. I have tested them from 5.0v to 16.5v and found they perform without issue. They also have a 1A linear BEC for powering your receiver. All in all pretty great for under 7 dollars.