Create Your Own UPDI Programmer - Arduino Project Hub
A simple and inexpensive way to program new AVR ATtiny214, ATtiny414, ATtiny814 and Atmega microcontrollers using by the UPDI interface - ООО "НПК "Спецтехнаука"
Space-saving FTDI / UPDI connector for the ATtiny3217 and others - Product Design - Arduino Forum
UPDI pin noise robustness in ATtiny | AVR Freaks
AVR Handheld programmer UPDI 12V Adapter to supply 12V pulse for UPDI interface reset.
AVR® Programming Interfaces - Developer Help
UPDI programmer compatible with Arduino IDE - Electronics-Lab.com