You will also need a method to shift the voltage level between 3.3V and 5V as the Raspberry Pi and Arduino operate at these different voltages respectively. We will make a slight modification to them in order to use the GPIO serial port.
Go ahead and check out my tutorial on how to install arduino-cli on Raspberry Pi if you don’t already have them on your system. You will need to install the Arduino command line tools so that Arduino can be programmed from the Raspberry Pi terminal. I would imagine that your interest in this tutorial means you are well beyond the point of needing a Raspbian installation guide! However if you need it for quick reference, you can check out my guide on how to install Raspbian. I would recommend connecting to the Pi using SSH so that it is easier to copy and paste the commands. This tutorial is suitable for headless machines, so you can use Raspbian Lite if you prefer.
You will need a Raspberry Pi with the latest version of Raspbian, check the latest price at Amazon. Connect the Arduino to the Raspberry Pi.
Or perhaps your dog ate your FTDI programmer and you want to make use of a spare Pi that you have lying around. If you are looking to make a custom Arduino-based Pi hat and want to provide firmware updates from the Pi then this is the ideal method. Looking to flash Arduino via the serial bootloader with the Raspberry Pi GPIO serial port? This article explains how to use the Raspberry Pi serial port to flash Arduino without having to use ICSP.