Many sites already described how to use the Arduino as a programmer for the ATtiny series, but as some people still have some problems with it, it won’t hurt to share my experience in doing this with an Arduino Nano.
The connection between the Arduino and the ATtiny is in essence the same, regardless of what Arduino one has. One needs to connect the ISP hearder between both chips. But for the UNO and the Nano there is a little addition in the form of a capacitor between ground and the reset pin:
Most circuits will show a 10uF electrolytic capacitor, but I used a 33uF elco and that worked perfectly.
In order to use the ATtiny 45 or 85 you need to download some software. For the Attiny13 there are other cores. If you are using the Attiny13 core you also need to create a boot.txt file
You will also find a core for the Attiny here. and a number of them here.
Now create a folder called ‘Hardware’ in the folder where your Arduino IDE saves it’s sketches. Unzip this file to the newly created hardware folder. If you had your Arduino IDE running, you need to close it and restart it so it can read the proper files.
Now do the following:
- Connect Arduino Nano and Attiny85 as described above, but do not connect the capacitor yet.
- Load the ‘Arduino as ISP sketch’
- Disconnect USB
- Insert capacitor
- Reconnect USB
- Load Attiny sketch of your choosing in the Arduino IDE (e.g. the ‘blink’ sketch)
- Choose ‘ATtiny85 with Arduino as ISP’ in yr ‘Tools->boards’
- Ignore the errors about PAGEL and BS2
- Remove USB
- Remove capacitor and at least the line to the reset of the Attiny (the one from pin 1)
Your sketch should now be correctly in your ATtiny.
Configuring the ATtiny to run at 8 MHz (for SoftwareSerial support)
By default, the ATtiny’s run at 1 MHz (the setting used by the unmodified “ATtiny45″, etc. board menu items). You need to do an extra step before the programming to configure the microcontroller to run at 8 MHz – necessary for use of the SoftwareSerial library. Once you have the microcontroller connected, select the appropriate item from the Boards menu (e.g. “ATtiny45 (8 MHz)”). Then, run the “Burn Bootloader” command from the Tools menu. This configures the fuse bits of the microcontroller so it runs at 8 MHz. Note that the fuse bits keep their value until you explicitly change them, so you’ll only need to do this step once for each microcontroller. (Note this doesn’t actually burn a bootloader onto the board; you’ll still need to upload new programs using an external programmer.)
With regard to writing a sketch for the ATtiny85, there is only a limited instruction set:
SoftwareSerial Apparently with 1.0 IDE
TinyWireM & TinyWireS: Wire (I2C / TWI) library for the ATtiny85 (using USI)