ATTINY24A_12 Datasheet, PDF (3/22 Pages) ATMEL Corporation – 8-bit Microcontroller with 2K/4K/8K Bytes In-System Programmable Flash

ATtiny24A/44A/84A
1.1 Pin Descriptions
1.1.1 VCC
Supply voltage.
1.1.2 GND
Ground.
1.1.3
Port B (PB3:PB0)
Port B is a 4-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port B output buffers have symmetrical drive characteristics with both high sink and source
capability except PB3 which has the RESET capability. To use pin PB3 as an I/O pin, instead of
RESET pin, program (‘0’) RSTDISBL fuse. As inputs, Port B pins that are externally pulled low
will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a
reset condition becomes active, even if the clock is not running.
Port B also serves the functions of various special features of the ATtiny24A/44A/84A as listed
in Section 10.2 “Alternate Port Functions” on page 58.
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 min-
imum pulse length is given in Table 20-4 on page 176. Shorter pulses are not guaranteed to
generate a reset.
The reset pin can also be used as a (weak) I/O pin.
1.1.5
Port A (PA7:PA0)
Port A is a 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port A output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port A pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port A pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port A has alternate functions as analog inputs for the ADC, analog comparator, timer/counter,
SPI and pin change interrupt as described in “Alternate Port Functions” on page 58.
3
8183FS–AVR–06/12