Programming an ATTiny13A Using Arduino & Servo Interpreter

So there I was, browsing eBay, looking for some cheap deals on Atmel chips when i came across a pair of ATTiny13 chips for £2.50. I just had to have them! After all, how hard can it be?

I needed a small chip to read servo signals from a hobby RC Receiver and control a laser output.

Once they arrived it dawned on me that I actually had no idea how to program these little chips. Dom and I spent hours trying various ways of ATTiny programming we found online with no luck. It was only until he left I sat down at my computer and found Tekstop's tutorial on 'Tiny programming that I had any success. With a couple of modifications to his files you will be up and programming these low price chips in no time!

Step 1: Connecting an ATTiny for Programming

Watch the video:

Connect your ATTiny13A to your arduino following the diagram below

Arduino pin 13 - ATTiny pin 7
Arduino pin 12 - ATTiny pin 6
Arduino pin 11 - ATTiny pin 5
Ardunio pin 10 - ATTiny pin 1
Arduino +5v - ATTiny pin 8
Arduino GNd - ATTiny pin 4

Optional:
GND - negative side of LED
ATTiny pin 3 - resistor (250 ohm) - positive side of LED

ATTINY13A Datasheet: http://www.atmel.com/Images/doc8126.pdf
Arduino ISP info: http://arduino.cc/en/Tutorial/ArduinoISP

Step 2: Setting Up the IDE

Open the arduino IDE and connect your Arduino
Go to file > Examples > ArduinoISP
Check you have the correct board & port selected (Tools > Board/Serial Port)
Press the upload button

This will program your arduino board to be used as an ISP (in system programmer)

Once complete, close the IDE

We now need to set up the IDE to recognise our ATTiny13A as an arduino compatible chip

Download and extract this file: https://github.com/tekstop/attiny/tree/Arduino1
Copy the folder "attiny" from the extracted ZIP to the /hardware/ folder in your arduino IDE installation directory

We then need to offset the clock speed (not a very elegant solution, but i'm working on it!):

Open Hardware/attiny/boards.txt
Scroll to the bottom of the file, this last few lines contains the data relevant to our chip
Change "attiny13.build.f_cpu=9600000L" to "attiny13.build.f_cpu=1000000L"

This will correct delay times etc.

Open the Arduino IDE again
Go to Tools>Board and select "ATtiny13 (internal 9.6 MHz clock)"

Step 3: Programming

You are now all set to upload your sketch to the attiny13a, make good use of its 1024 bytes of internal memory! ;)

Open the IDE
Click File>Examples>Basic>Blink
Change line 11 from "pinMode(13, OUTPUT);" to "pinMode(4, OUTPUT);"
Change line 15 from "digitalWrite(13, HIGH);" to "digitalWrite(4, HIGH);"
Change line 17 from "digitalWrite(13, LOW);" to "digitalWrite(4, LOW);"
Click File>Upload using programmer

The IDE should now upload the sketch to your chip via your ArduinoISP programmer!
Once this is complete (~5 seconds) your LED should start blinking with a 1 second interval

To address pins in the Arduino IDE you should use their PB number from the diagram below (EG Pin1 = PB1 etc..)

If all you wanted to do was learn to program your chip, then congratulations! You are done!
If you would like to build a RC Servo Interpreter then keep reading.

Step 4: Building the Servo Interpreter

Check out my YouTube video below for an easy walk through of how to program the software

Code is available in attached text file.

Connect the LED and resistor in exactly the same way as Step 1 states for testing purposes
If you use a relay it should be rated at 5V for the coil.
Connect the coil between pin 4 and GND
If using a relay you should also use a diode to protect the ATTiny from EMF by wiring it across the relay coil, negative(white band) side connected to pin 4.