Using a Raspberry Pi to Program an AVR and Python SPI Tutorial - YouTube
AVR
A simple and inexpensive way to program new AVR ATtiny214, ATtiny414, ATtiny814 and Atmega microcontrollers using by the UPDI interface - ООО "НПК "Спецтехнаука"
microcontroller - Help with AVR ADC and Serial port programming and integrating with python - Electrical Engineering Stack Exchange