Now that I’ve put wheels and motors on my quad, I need a motor controller. Of course, I’ll have to build my own… 8) . The ready-made ones that have a useful interface are too expensive. The cheaper ones are little more than an H-bridge chip on a board (you have to provide your own logic for on/off, speed, and direction).
The current plan is this:
An SN754410 H-bridge chip.
A PIC 16F88 MPU.
Protection diodes, and a few misc. R’s and C’s.
The interface will be I2C, so that my bot’s main MPU can easily talk to it.
The I2C commands will control on/off, speed, and direction for each of 2 motors.
I’ll use the 16F88 because it is the smallest DIP-package PIC that supports I2C. Plus my sensor board already uses one, so some of the SW will be common. Plus I have a bunch of them…
That looks like a nice article!
Yes, I’m using a single-chip solution because it’s cheap (about $2.50), simple (only one part plus the MPU and some diodes), compact, etc.
I needed an MPU anyway to get the I2C interface, so it’s very simple in SW to make the signals that the H-bridge chip needs. It’s only a slight variation off of my servo-PWM code that is already working - the only real difference is the frequency will be much higher than 50 Hz.
My motors use less than 0.25 amps, so I don’t need the big MOSFETs and such.
If I ever need something bigger, I have plenty of big beefy MOSFETs that can easily switch several amps.
Thanks Andy,
That OSMC looks very nice, although its not cheap enough where I would buy it (rather than build my own), and an MPU is still required.
I’ve seen a number of motor controllers that have an R/C servo interface, but I’d really prefer I2C…
The thing on the right that looks like 2 back-to-back power transistors are really resistors, 5 ohms each (R2 on the schematic).
The 20-pin header has all the signals coming and going.
The 10-pin header is for programming the PIC.
