If you have been playing around with your digispark, be sure the bootloader and board in the Arduino IDE are set correctly to the board you are now programming.Īfter uploading, go to tools > port and note the port where your Arduino is connected. Using the Arduino IDE (I used v1.6.6), go to file > examples > ArduinoISP and upload this sketch to your Duemilanove (or Uno). The next thing you will need is another Arduino, I used a Duemilanove, but you can also use an Uno. You will still be able to upload programs via the USB connection as you normally do after changing the configuration fuse. If you can upload programs to your ATTINY85USB via the USB connection from the Arduino IDE the bootloader is present and working. Ok, so now you know that your pin 5 is configured as a reset pin and you want it for GPIO.įirst and foremost be sure the micronucleus bootloader is installed on your ATTINY85 and working properly.Īfter we change the configuration fuse, you will not be able to load micronucleus without a high voltage programmer! Be sure the bootloader is present and working first. High voltage programmer, which is fairly simple to build and use, but itīeyond the scope of this post. (If pin 5 is working for GPIO and you want change it to a reset pin, it is possible. If the program resets (the micronucleus bootloader waits 5 seconds and then the program runs) you cannot use pin 5 for GPIO.

If it doesn't work pin 5 will not work for GPIO.Īnother simple test would be to pull pin 5 to ground through a small resistor (~220 ohms) while a program is running. One would be to upload a sketch that blinks an led on pin 5, if it works that's great! You don't need to change anything.

To test if your clone can use pin 5, there are some simple methods. This is well documented on the digistump site.Īfter the bootloader is added, we no longer need that reset pin, and on the genuine boards they go ahead for us and set the 'fuse' on the ATTINY85 to disable the reset pin, allowing it to be used as a GPIO pin. The micronucleus bootloader allows the user to program the ATTINY85 with a USB connection. The ATTINY85 comes from the factory set up for ISP (in system programming), for this to work it needs a reset pin. If you only need 5 pins, or want a reset pin that's great, you can stop reading. The catch is that pin P5 (the last one, physically counted as number 6, ADC0) may be configured as a reset pin. There are Chinese clones available on ebay for about $1.50 that are pin for pin compatible and come with the micronucleus bootloader installed.

The genuine version, available here: comes with the micronucleus bootloader installed and 6 GPIO pins enabled. The digispark ATTINY85 is a handy microcontroller for simple projects.

Attiny85 digispark reprogramming