at90pwm81-16se ATMEL Corporation, at90pwm81-16se Datasheet - Page 7

• Manufacturer Part Number: at90pwm81-16se
• Description: 8-bit Avr Microcontroller With 8k Bytes In- System Programmable Flash
• Manufacturer: ATMEL Corporation

3.1.4
3.1.5
3.1.6
7734M–AVR–03/10
Port D (PD7..PD0)
Port E (P32..0) RESET/ XTAL1/
XTAL2/AREF
AVCC
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D
output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs,
Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port
D pins are tri-stated when a reset condition becomes active, even if the clock is not running.
Port D also serves the functions of various special features of the AT90PWM81 as listed on
page 76
Port E is an 4-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port E
output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs,
Port E pins that are externally pulled low will source current if the pull-up resistors are activated. The Port
E pins are tri-stated when a reset condition becomes active, even if the clock is not running.
If the RSTDISBL Fuse is programmed, PE0 is used as an I/O pin. Note that the electrical characteristics of
PE0 differ from those of the other pins.
If the RSTDISBL Fuse is unprogrammed, PE0 is used as a 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
Depending on the clock selection fuse settings, PE1 can be used as input to the inverting Oscillator ampli-
fier and input to the internal clock operating circuit.
Depending on the clock selection fuse settings, PE2 can be used as output from the inverting Oscillator
amplifier.
The various special features of Port E are elaborated in
tems and their Distribution”, page 27.
AVCC is the supply voltage pin for the A/D Converter. It should be externally connected to V
the ADC is not used. If the ADC is used, it should be connected to V
Table 8-1 on page
50. Shorter pulses are not guaranteed to generate a Reset.
Table 10-9 on page 78
CC
through a low-pass filter.
AT90PWM81
and Section “Clock Sys-
Table 10-6 on
CC
, even if
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