Hi slowjourney
To work with digital pin 8 (i.e. the one marked D8 on the PCB next to the pin), remove these from your code:
#define CHIP_PIN_28 28
#define PB4 CHIP_PIN_28
#define MICRO_D8 PB4
... and just do this:
pinMode(8, OUTPUT);
digitalWrite(8, HIGH);
Regards
Ray