This a simple, header-only C++ library for using a Teensy 4.0 development board to run brushless motors via an electronic speed controller (ESC) supporting the popular OneShot125 protocol. I adapted the code from Nicholas Rehm's awesome dRehmFlight repository, with the goal of allowing fellow Teensy lovers to use this kind of ESC in other projects.

As shown in the sketch below (which I used for making this video), the API for the library is very simple:

1. Declare a OneShot125 object, passing it a list of pins.

2. In your setup() function, call the object's arm() function to arm the motors.

3. In your loop() function, call the object's set() function to set the pulse width on each pin; then call the run() function to run the motors at the specified pulse widths.

static const std::vector<uint8_t> PINS = {0, 1};

static auto motors = OneShot125(PINS);

void setup() 
{
    Serial.begin(115200);

    inputInit();

    motors.arm(); 
}

void loop() 
{
    auto pulseWidth = (uint8_t)(125 * (inputGet() + 1));

    motors.set(0, pulseWidth);
    motors.set(1, pulseWidth);

    motors.run();

In this sketch, inputInit() is a (possibly empty) function that sets up your input device, such as an R/C receiver, or the potentiometer used in the video. The inputGet() function returns a floating-point value between 0 and 1, such as the normalized throttle or potentiometer reading.

Calibrating your ESCs

Before using this library in your project, you should calibrate the ESCs. Calibration means that when your input (e.g., throttle stick) is in its max position, you send the maximum pulse with of 250 uSec to each ESC, and when your input is at its minimum you send the minimum 125uSec pulse width. Because of the potential to spin the motors unexpectedly, you should make sure to remove the propellers from your motors before calibrating.

The calibration sketch allows you to calibrate your ESCs using either the sort of potentiometer shown in the video, or the more common method of an R/C transmitter/receiver. This sketch supports the popular DSMX and SBUS protocols, which you can select by un-commenting on of the #include lines at the top of the sketch. The DSMX version requires this Arduino library, and the SBUS version requires this library. This video shows me using the SBUS version, with a FrSky transmitter and receiver. As you can see in the video, calibration uses the following steps:

1. With the battery and Teensy unplugged, turn on the transmitter and max-out the throttle.

2. Plug in the Teensy board. If it is receiving full throttle correctly, the LED will turn on.

3. Plug in the battery. You should immediately hear the calibration starting melody.

4. Lower the throttle stick on the transmitter all the way. You should see the LED turn off and should immediately hear the calibration completed melody.

5. Unplug the battery

In the calibration sketch I've used the Serial2 UART for the receiver and pins 0 and 1 for the ESCs, but you should be able to use any leigitimate serial port or pins in your copy of the sketch.

Testing and deploying

I've also provided a testing sketch that you can use to test your setup after calibrating, and to deploy in an actual project. As with the calibration sketch, you should make sure to remove an propellers before running the sketch, and un-comment the #include lines at the top of the sketch to match your input device.