IR Tracking Turret with PIC and C

This is a good learning project that is fun to build – I got a lot out of making it. I think this has been done quite a bit already, but I did not find a straightforward way of doing this with PICs. When I finally got it working, I thought I’d share it. It might be useful for someone that wants to learn or apply I2C, Interrupts and Callbacks, PWM, or Servo Control.

Basic Functionality

Detects and tracks an infrared light source. Pans or tilts when the light source moves away from the center of the frame, attempting to keep it in the center.

Main Components

• Pixart IR Camera
• PIC16F1503 (a 14-pin, 8-bit PIC microcontroller)
• Voltage Regulator
• Servos

Assumptions

• You can solder and desolder through-hole components
• You have a computer
• You can read a data sheet

Take-Away Skills

• 8-bit PIC programming in C using MPLAB X, XC8 and MPLAB X Code Configurator
• I2C Protocol
• Using microcontroller timers
• PWM servo control, and getting maximum resolution in movement
• Using an adjustable voltage regulator

You might also learn a little about

• IR Wavelengths
• Camera field of view
• Using one power source for servos and microcontroller
• Calibrating the Pixart camera module
• Making something with room for expansion

No PCB etching required 🙂 I made this with stripboard and just cut traces and added jumpers where needed. It is also doable on a small breadboard. My first prototype fit the voltage regulator and main board components on one 17×10 breadboard.

This project should cost less than 25 EUR even if you have no spare parts laying around.

There are unused pins on the PIC16F1503 and I’ve included male headers for all pins in the stripboard pcb, so in-circuit programming is possible and there is room for expansion (another servo, more sensors, rocket launchers…).

Step 1: Tools and Materials

You can find a broken WiiMote for cheap,I got one from Game Over in Amsterdam for 1 EUR. Broken WiiMotes are usually easy to find and the camera module is almost always OK – it’s the buttons that wear out.

Pixart Camera Board

• 1.5×1.3cm pice of stripboard (6×5 holes, with 5 holes along the strip)
• 6×1 male header
• 3×2 or two 3×1 male headers
• Something to pot the camera connections

For the camera module

Front of Camera (bottom view)

7 5 3 1
8 6 4 2

• Remove it from the WiiMote – desoldering braid works best, but I did manage to remove two intact with a blowtorch 🙂
• Clip pins 3 and 4 – we don’t need them
• Nudge pins 5 and 6 a little toward the center and nudge the other as necessary to make them line up with the pins on the 3×2 or two 3×1 headers
• Solder the camera pins to the header pins
• Test the continuity of the connections
• Pot the soldered connections in sugru, silicone, etc. – or just carefully wrap it with a piece of tape 🙂
• Done!

Voltage Regulator Board

• 2.4×1.2cm piece of stripboard (9×4, with 9 holes along the strip)
• LM317
• 240 ohm resistor (I used two 120 ohm in series)
• 380 ohm resistor
• .1 uF capcitor
• 3300 uF capacitor (you can get this from the WiiMote as well, else anything comparable will do)
• 4×1 male header

Main Board

• 4x4cm piece of stripboard (15×15 holes)
• 2x 7×1 make headers
• 2x 6×1 male header
• 4×1 male header
• PIC16F1503
• 25MHz oscillator
• Red LED
• 1x 220 ohm resistor
• 2x 2.2K ohm resistor
• .1 uF capacitor

Notes

Headers: Right-angle or straight will work – I actually wish I had used right-angle headers on the main board to keep things flatter.

Step 3: Design