The Paperduino Tiny runs the “micronucleus tiny85” bootloader version 1.06, an open source project written by Bluebie: https://github.com/Bluebie. Digistump supported the development and donated the VID/PID pair for the USB device.
You can find the source in: https://github.com/micronucleus/micronucleus
You can download bootloader: micronucleus-1.06-upgrade.hex.zip
It is very important to use correct fuses bit when burning bootloader to ATtiny85, below list the fuses bit for burning bootloader:
Please note that these fuses setting not enable reset pin (ATtiny85 pin 1) as I/O pin, so you only have 5 I/O pins but you are able to reprogramm ATtiny85 with other software withou HV programmer.
If you are experienced user you can set RSTDSBL bit to enable 6 I/O pins:
With avrdude and USBasp with RSTDSBL:
avrdude -c usbasp -p t85 -U flash:w:micronucleus-1.06-upgrade.hex -U lfuse:w:0xe1:m -U hfuse:w:0x5d:m -U efuse:w:0xfe:m
avrdude -c usbasp -p t85 -U flash:w:micronucleus-1.06-upgrade.hex -U lfuse:w:0xe1:m -U hfuse:w:0xdd:m -U efuse:w:0xfe:m
You will need:
5 x 1K resistors (or similar)
A connection to the GPIO of the Pi, and a breadboard and wire.
sudo apt-get install bison automake autoconf flex git gcc sudo apt-get install gcc-avr binutils-avr avr-libc git clone https://github.com/kcuzner/avrdude cd avrdude/avrdude ./bootstrap && ./configure && sudo make install
Download and build WiringPi for the gpio commands
cd ~ git clone git://git.drogon.net/wiringPi cd wiringPi ./build
Connect up the ATtiny85 to the Raspberry Pi GPIO
Test avrdude connection to the ATtiny85, we are set up with GPIO pin 22 on the ATtiny reset. We must pull this pin low to program the chip. This can be done in other ways, e.g. a switch, but I an using another pin of the GPIO to do this.
sudo gpio -g mode 22 out sudo gpio -g write 22 0 sudo avrdude -p t85 -P /dev/spidev0.0 -c linuxspi -b 10000 sudo gpio -g write 22 1
This must give success type messages!
sudo gpio -g mode 22 out sudo gpio -g write 22 0 avrdude -P /dev/spidev0.0 -c linuxspi -b 10000 -p t85 -U flash:w:micronucleus-1.06-upgrade.hex -U lfuse:w:0xe1:m -U hfuse:w:0x5d:m -U efuse:w:0xfe:m sudo gpio -g write 22 1
You can make ISP programmer from old USB keyboard:
If you are not able to burn bootloader you can buy ATtiny85 with bootloader + 3 original paperduino cards for 5 USD with Worldwide shipping.