@Koh_Biet The Digispark uses the ATtiny85. Has 4 pins free. With charliplexing that can be 20 buttons.
Personal blog of Peter "Sci" Turpin
Technology, art and personal faff
@Koh_Biet The Digispark uses the ATtiny85. Has 4 pins free. With charliplexing that can be 20 buttons.