ServoControl

This is a small program to control a couple of servo motors directly connected to two PWM output signals on the Raspberry Pi Zero W.

I'm using Arch Linux ARM as my Linux distribution, but I assume that it'll compile under other distributions too. If you compile for another distribution, feel free to update with instructions.

Prerequisites

1. A couple of servos, possibly with a pan and tilt kit. I bought mine on Ebay (this kit from ms_graphics).
2. A Raspberry Pi Zero W, as it's handy to control the camera wirelessly
3. A separate power supply for servo and Raspberry. Seriously, it is absolutely essential! Make sure that the GND is the same on the supplies though. I am using a power supply with two USB outputs
4. That the Pan servo is connected to GPIO 18 and the Tilt servo is on GPIO 19 (pins 12 and 35 respectively)

Assumptions

That you...

1. ... are confident installing software on your OS of choice
2. ... know how to change directories, running programs etc.
3. ... have the base-devel and git packages installed (sudo pacman -S base-devel git)
4. ... are able to run sudo (check out the wiki for how to set that up)

Libraries

Make sure that you have all the libraries necessary to build this. The program uses ncurses, rt and pigpio.

The excellent PiGPIO library isn't installed in Arch Linux ARM and I don't think there's an AUR for the C-bindings. I just installed it myself as it's straight-forward enough:

git clone https://github.com/joan2937/pigpio
cd pigpio

Edit the Makefile to use /usr instead of /usr/local if you're on Arch (line starting with prefix), make the library and install it:

sed -i -e 's/\(prefix = \/usr\)\/local/\1/' Makefile
make
sudo make install

How to build

It should just be to clone this repository and build the program:

git clone https://github.com/nolltre/ServoControl.git
cd ServoControl
make

If you are using another GPIO, adjust that in the servo.c file.

How to run

If you haven't changed any permissions for accessing the GPIOs, you will need to run the program as root:

sudo ./servo

Controls

• h, j, k, l moves the servo left, down, up and right
• s stops the PWM signal (0% duty cycle)
• q quits the program

So how does it look?

These are just some images showing how your kit might turn out. I removed some of the plastic tabs on the pan & tilt kit and hotglued the official Raspberry Pi Zero case.

Image