ATA8743 ATMEL Corporation, ATA8743 Datasheet - Page 21

• Manufacturer Part Number: ATA8743
• Manufacturer: ATMEL Corporation

9.3
9.3.1
9.3.2
9.3.3
9.3.4
9.3.5
9152A–INDCO–07/09
Pin Descriptions
VCC
GND
Port B (PB3...PB0)
RESET
Port A (PA7...PA0)
Supply voltage.
Ground.
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 ATtiny24/44/84 as listed on
Section 19.3 “Alternate Port Functions” on page
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. The minimum pulse length is given in
56. Shorter pulses are not guaranteed to generate a reset.
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 an alternate functions as analog inputs for the ADC, analog comparator, timer/coun-
ter, SPI and pin change interrupt as described in
77.
“Alternate Port Functions” on page 77
Figure 16-1 on page
ATA8743
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