Port B also serves the functions of various special features of the ATtiny25/45/85 as listed in “Alternate Functions
of Port B” on page 60.
On ATtiny25, the programmable I/O ports PB3 and PB4 (pins 2 and 3) are exchanged in ATtiny15 Compatibility
Mode for supporting the backward compatibility with ATtiny15.
1.1.4
RESET
Reset input. A low level on this pin for longer than the minimum pulse length will generate a reset, even if the clock
is not running and provided the reset pin has not been disabled. The minimum pulse length is given in Table 21-4
on page 165. Shorter pulses are not guaranteed to generate a reset.
The reset pin can also be used as a (weak) I/O pin.
ATtiny25/45/85 [DATASHEET]
3
2586PS–AVR–06/2013