Tools

• Development board.  I use the Konijntje-thermo-humi board from a previous project.
• ISP programmer.  I use the Atmel AVRISP MkII

PlatformIO setup

1. Create a new project and select "Generic ATtiny84 (Atmel)".  The Arduino-framework will automatically be selected.
2. Adjust the platformio.ini file:

   [env:attiny84]
   platform = atmelavr
   board = attiny84
   framework = arduino
   upload_protocol = avrispmkII
   upload_port = usb
   
   ; https://www.engbedded.com/fusecalc/
   board_build.f_cpu = 1000000L
   board_fuses.lfuse = 0x62
   board_fuses.hfuse = 0xD7
   board_fuses.efuse = 0xFF
   upload_flags =
       -B  ; bit clock needs to be slowed down (original=1) when underclocking the MCU
       10
   
   lib_deps =
       stevemarple/AsyncDelay @ ^1.1.2
       thomasfredericks/Bounce2 @ ^2.70
   
   ; FTDI TTL-232R-3V3-WE
   monitor_port = /dev/ttyUSB0
   monitor_speed = 4800

3. Simply hit the "Upload"-button to program your device.

That's it.  No makefiles, no menu configs.

Remember to upload your code again after programming the fuses (if needed).

Here goes the blinkenlight example:

LED_BUILTIN = PIN_PB2

#include <Arduino.h>

void setup()
{
    // put your setup code here, to run once:
    pinMode(PIN_PB0, OUTPUT);
}

void loop()
{
    // put your main code here, to run repeatedly:
    digitalWrite(PIN_PB0, HIGH);
    delay(500);
    digitalWrite(PIN_PB0, LOW);
    delay(500);
}

framework-arduino-avr-attiny

More info about the framework (and the pin numbering) can be found on:

• SpenceKonde/ATTinyCore for ATtiny84
• platform-atmelavr