This firmware will turn a Raspberry Pi Pico with two DRV8833 motor controller boards into a USB Midi to DC Motor controller of sorts.
It maps midi notes to one of the 4 currently available channels and uses the velocity of the notes to set the speeds.
It also features a small auto sleep function which will activate the DRV8833's sleep mode when idle.
These are the midi messages expected by the device, and their effect.
In all note on messages, the velocity is mapped to the speed of the motor.
| midi message | motor | effect |
|---|---|---|
| note on 48 | motor 1 a | reverse |
| note off 48 | motor 1 a | stop |
| note on 49 | motor 1 b | reverse |
| note off 49 | motor 1 b | stop |
| note on 50 | motor 2 a | reverse |
| note off 50 | motor 2 a | stop |
| note on 51 | motor 2 b | reverse |
| note off 51 | motor 2 b | stop |
| note on 60 | motor 1 a | forward |
| note off 60 | motor 1 a | stop |
| note on 61 | motor 1 b | forward |
| note off 61 | motor 1 b | stop |
| note on 62 | motor 2 a | forward |
| note off 62 | motor 2 a | stop |
| note on 63 | motor 2 b | forward |
| note off 63 | motor 2 b | stop |
The serial interface allows you to control the motors via serial commands. The general format of a command is set <motor> <property> <value>. Here's a breakdown of the command structure:
| Command Part | Description | Valid Values |
|---|---|---|
<motor> |
Specifies which motor to control. | 1a, 1b, 2a, 2b |
<property> |
Specifies which property of the motor to set. | speed, dir, stop, sleep, decay |
<value> |
Specifies the value to set the property to. | Depends on the property. For speed, it's a float between 0 and 1. For dir, it's either forward or reverse. For stop and sleep, it's not used. For decay, it's either fast or slow. |
Here are some examples of valid commands:
set 1a speed 0.5: Sets the speed of motor A on motor driver 1 to 0.5.set 2b dir forward: Sets the direction of motor B on motor driver 2 to forward.set 1a stop: Stops motor A on motor driver 1.set 2b sleep: Puts motor B on motor driver 2 to sleep.set 1a decay fast: Sets the decay mode of motor A on motor driver 1 to fast.
You need to have platformio installed to make use of this.
Install it on MacOS by running homebrew:
brew install platformioTo compile and upload your sketch, simply run the following command:
pio run -t upload