This post is a summary that covers how to turn your Arduino board into an ISP programmer and use it to program an ATtiny85 or 45 8-pin microcontroller.

The instructions in this post are based on the following two tutorials written by David Mellis:
Arduino board as ATtiny programmer >> http://hlt.media.mit.edu/?p=1706
Programming an ATtiny w/ Arduino 1.0.1 >> http://hlt.media.mit.edu/?p=1695

If you get fed up with all the wires, see how to make your own ATtiny programming shield for Arduino:
>> http://www.kobakant.at/DIY/?p=3996

Turning your Arduino into an ISP Programmer

What is an ISP (In System Programmer)???
The answer >> http://en.wikipedia.org/wiki/In-system_programming

1 Materials and Tools

– Laptop with the Arduino software version 1.0.1 or 0022 installed
– Arduino Uno or Duemilanove (with an ATmega328, not an older board with an ATmega168!)
– USB cable
– ATtiny45 or ATtiny85 (Sparkfun, DigiKey, RS)
– 10 uF capacitor
– Breadboard
– Jumper wires

2 Download and Save the ATtiny Folder

– Download the “ATtiny” folder from this GitHub repository:
>> https://github.com/damellis/attiny/tree/Arduino1
– In your Arduino sketchbook folder create a new sub-folder called “hardware”
– Put the “ATtiny” folder inside this “hardware” folder
– You should end up with folder structure like this: “Documents > Arduino > hardware > attiny”

– Quit and restart the Arduino software
– Look inside the “Tools > board” menu and you should see the ATtiny entries

3 Upload “ArduinoISP” to your Arduino

– Open “ArduinoISP” sketch from “Examples” folder
– Select “Arduino Uno” from the “Tools > Board” menu
– Upload sketch

Using your Arduino ISP to Program an ATtiny Microcontroller

1 Wiring your ISP connection

ATtiny —– Arduino
Pin PB2 (SCK) —– Pin 13
Pin PB1 (MISO) —– Pin 12
Pin PB0 (MOSI) —– Pin 11
Pin PB5 (Reset) —– Pin 10
Plus (VCC) —– +5V
Minus (GND) —– GND

10uF Capcitor:
Arduino pins: RESET —-||—- GND

How a breadboard is internally connected:

How to connect the Arduino and the ATtiny using the breadboard, jumper wires and one 10uF capacitor:

2 Burn Bootloader

To set the clock speed of your ATtiny to be faster (8Mhz) than the default 1 MHz.
– Select “ATtiny45 (8 MHz)” from the “Tools > Board” menu
– Select “Arduino as ISP“ from the “Tools > Programmer” menu
– Select “Burn Bootloader” from the “Tools” menu

“ATtiny45 (8 MHz clock)”:

“Arduino as ISP”:

“Burn Bootloader”:

3 Writing a Sketch for the ATtiny

Download the ATtiny25/45/85 datasheet >> http://at.rs-online.com/web/p/microcontroller/6962339/

The following Arduino commands are supported for the ATtiny:

4 Uploading a Sketch to the ATtiny

– Open the sketch you want to upload to ATtiny
– Select “ATtiny45 (8 MHz)” from the “Tools > Board” menu”
– Select “Arduino as ISP“ from the “Tools > Programmer” menu
– Upload sketch
– The following error message is okay:

Notes

– Once you have added parts to your circuit that connect to the programming pins of the ATtiny, you may need to disconnect these parts before uploading a new program.
– Once you have programmed your ATtiny, you may need to remove the programming connections in order for your circuit to function correctly.
– Make sure you have a compatible version of the Arduino software installed. At the time of writing this post version 1.0.1 worked, but verion 1.0 had bugs and version 1.0.2 was not working at all.
– Remember to remove the capacitor when uploading the Arduino ISP sketch to the Arduino Uno or Duemilanove and to put the capacitor back for burning the bootloader and uploading any sketches to your ATtiny.
– Declare IN- and OUTPUTS refering to the pin’s port number: pinMode(PB#, INPUT);
– When reading an analog input, refer to the pin’s ADC number: analogRead(ADC#);
– To set the internal pull-up resistors write the following into the setup() function:
pinMode(4, INPUT);
digitalWrite(4, HIGH);
Because we have declared pin 4 to be an INPUT, writing HIGH to the pin will set the internal pull-up.

Checklist:

Turning your Arduino into an ISP Programmer

No capacitor!
1. Download the Arduino software and install it
2. Download the ATtiny folder and save it in a “hardware” folder in your Arduino sketch folder
3. Restart Arduino
4. Open “ArduinoISP” sketch from “Examples” folder
5. Select “Arduino Uno” from the “Tools > Board” menu
6. Select “/dev/tty/usbserial###” from the “Tools > Serial Port” menu
7. Upload sketch

Using your Arduino ISP to Programming an ATtiny Microcontroller

Add capacitor and programming connections!
1. Select “ATtiny45 (8 MHz)” from the “Tools > Board” menu
2. Select “Arduino as ISP“ from the “Tools > Programmer” menu
3. Select “Burn Bootloader” from the “Tools” menu (yes capacitor)
4. Open the sketch you want to upload to the ATtiny
5. Upload sketch (yes capacitor)

The following error message is okay: