We found this Arduino AVR ISP programmer particularly interesting. AVR microcontrollers can utilize an interface called In-System-Programming. ISP allows the chip to be programmed or reprogrammed ...

//This code shows how to upload a code to attiny using arduino as ISP in Platformio //at first upload code to arduino as ISP from arduino ide>example>arduinoISP //next connect the arduino to attiny ...

A small example about using Arduino UNO as the ISP to write a simple blinking program to ATtiny85 - ChenW12/Blinking_on_ATtiny85 ...