nerves_livebook

# Controlling A Servo With PWM

## Introduction

in this notebook we will be controlling a servo on a raspberry pi with the `Pigpiox` library which uses the [pigpio](https://abyz.me.uk/rpi/pigpio/index.html) library under the hood. You will need an [SG90](http://www.ee.ic.ac.uk/pcheung/teaching/DE1_EE/stores/sg90_datasheet.pdf) servo motor or something similar.

## Try it out

Lets set a variable so that we don't have to choose the GPIO pin every time.

First, refer to the GPIO ports for your Nerves device.
In this example, we will be using pin 12 on the raspberry pi platform.

![](https://raw.githubusercontent.com/nerves-livebook/nerves_livebook/main/assets/gpio/rpi_pinout.png)

Wire everything up like in the diagram below. Servos have 3 wires: ground, vcc and pwm. In this case the black is ground the red is vcc and the yellow is pwm. Hook it up to pin 12 of the raspberry pi.

![](https://raw.githubusercontent.com/nerves-livebook/nerves_livebook/main/assets/gpio/rpi_servo.png)

Lets set the pin as a variable so we don't have to choose the GPIO pin every time.

```elixir
pin = 12
```

Now we can set the servo to neutral or 90 degrees with the following command.

```elixir
Pigpiox.Socket.command(:set_servo_pulsewidth, pin, 1500)
```

Here we can set it to 0 degrees.

```elixir
Pigpiox.Socket.command(:set_servo_pulsewidth, pin, 500)
```

And now 180 degrees.

```elixir
Pigpiox.Socket.command(:set_servo_pulsewidth, pin, 2500)
```

Refer to the data sheet for your servo. You may need to change the values.You can learn more about how servos work [here](https://www.jameco.com/Jameco/workshop/Howitworks/how-servo-motors-work.html).