This process uses a modified version of the official Raspberry Pi OS (2020-02-13-raspbian-buster-lite.img). It has been configured with the tools necessary to burn an Arduino style bootloader using the Raspberry Pi’s GPIO pins (described here).

Brief summary of steps:

• Wire Raspberry Pi GPIO pins to Arduino ICSP pins
• Boot the custom Raspberry Pi image
• Connect a computer to Raspberry Pi WiFi
• SSH into Raspberry Pi
• cd to ‘/arduino’ and run ‘./burn.sh’

This requires a Raspberry Pi and six jumper wires to connect to your target Arduino or similar microcontroller. Once the Raspberry Pi is booted, it will broadcast an SSID (unsecured). Once connected to the Raspberry Pi, an SSH client such as PuTTY can be used login and execute commands. Alternatively, a keyboard and monitor can be attached directly.

I will be using an Arduino Uno with the 328p microcontroller, but multiple microcontrollers are supported.

Getting Started

Download the image

Download Link – 460MB

MD5: 543417af80e140c609b8dec69a09f229

Write the image to an SD card

I recommend using the official Raspberry Pi imager. Linux’s ‘dd’, Balena Etcher, or similar programs can also work. The image file is compressed using ‘xz’ — the Raspberry Pi imager will automatically decompress the image, but you may need to do this manually for other programs.

You will need a 4GB microSD card.

Booting and credentials

Once booted, the Raspberry Pi should broadcast an SSID of “raspberry”. This is an open wifi hotspot. You will need to connect and login using any SSH client.

You can also connect a keyboard and monitor directly.

SSID: raspberry
passkey: none (open)

IP Address: 192.168.2.1
username: root
password: pi

Wiring Example

This image shows the wiring from the Raspberry Pi to the Arduino Uno’s ICSP pin header. Not all ICSP pin headers are the same. If you don’t have any ICSP headers, you will need to determine which pins directly correspond to the SCK/MOSI/MISO and VCC/GND/RST.

avrdude Command

Once you’re connected to the Raspberry Pi, there is a directory called ‘/arduino’ that contains the avrdude configuration file, different bootloaders, and a script called ‘burn.sh’ that has examples of how to burn programs to different Arduino boards.

‘burn.sh’ contains a few examples. You will need to use the correct command and fuse settings to match your microcontroller.

Below is the command to burn the blink program (which happens to include a bootloader) to the Arduino Uno. The fuse bytes are included, but not necessary if you want to keep the existing fuse settings.

avrdude -C /arduino/avrdude.conf \
	-p atmega328p \
	-c pi_1 -v \
	-U flash:w:/arduino/hex/atmega328p_blink.hex:i \
	-U lfuse:w:0xf7:m \
	-U hfuse:w:0xd6:m

The -U flag, further details

Performs memory operations. Multiple operations can be performed in one command.

-U memtype:op:filename[:format]

memtype

• calibration One or more bytes of RC oscillator calibration data.
• eeprom The EEPROM of the device.
• efuse The extended fuse byte.
• flash The flash ROM of the device.
• fuse The fuse byte in devices that have only a single fuse byte.
• hfuse The high fuse byte.
• lfuse The low fuse byte.
• lock The lock byte.

op

• r read memory and write to file
• w read file and write to memory
• v read memory and file, verify both

format (optional)

• i Intel Hex
• s Motorola S-record
• r binary, little-endian
• m immediate, 0x for HEX values

Examples

Uploading blink sketch to ATtiny85

avrdude -C /arduino/avrdude.conf \
    -p t85 -c pi_1 -v \
    -U flash:w:/arduino/hex/attiny85_blink.hex:i \
    -U lfuse:w:0xE2:m \
    -U hfuse:w:0xDF:m \
    -U efuse:w:0xFF:m \
    -U lock:w:0xFF:m 

Uploading Adafruit OLED demo to Nano

This sketch takes a little longer to upload and it’s easier to “see” avrdude doing its thing.

avrdude -C /arduino/avrdude.conf \
    -p atmega328p -c pi_1 -v \
    -U flash:w:/arduino/hex/atmega328p_oled.hex:i \
    -U lfuse:w:0xf7:m \
    -U hfuse:w:0xd6:m

Reading EEPROM from ATmega8

I’ve programmed a message into the EEPROM of an ATmega8A and I will read it back to a file called ‘eeprom.dump’ and then I will hexdump the file to see the message.

avrdude -C /arduino/avrdude.conf \
-p m8 -c pi_1 -v \
-U eeprom:r:/arduino/eeprom.dump:r

Compiling Sketches on the Raspberry Pi

‘arduino-cli’ is installed. Within the ‘/arduino’ directory is the standard ‘blink’ program. The script ‘compile.sh’ has an example of how to compile using ‘arduino-cli’

arduino-cli compile --fqbn arduino:avr:uno -v blink/ --output-dir blink

This command will produce the compiled program, including a HEX file, that can be uploaded.

Samba Filesharing

The Raspberry Pi has Samba installed and is sharing the ‘/arduino’ directory.

Common ‘part’ names

These are used with the ‘avrdude’ command and the ‘-p’ flag.