Table 29. Overriding Signals for Alternate Functions in PA3..PA0(1)
Signal
Name
PA3/AD3
PA2/AD2
PA1/AD1
PUOE
SRE
SRE
SRE
PUOV
~(WR | ADA) •
PORTA3 • PUD
~(WR | ADA) •
PORTA2 • PUD
~(WR | ADA) •
PORTA1 • PUD
DDOE
SRE
SRE
SRE
DDOV
WR | ADA
WR | ADA
WR | ADA
PVOE
SRE
SRE
SRE
PVOV
A3 • ADA | D3
OUTPUT • WR
A2• ADA | D2
OUTPUT • WR
A1 • ADA | D1
OUTPUT • WR
DIEOE
0
0
0
DIEOV
0
0
0
DI
D3 INPUT
D2 INPUT
D1 INPUT
AIO
–
–
–
PA0/AD0
SRE
~(WR | ADA) •
PORTA0 • PUD
SRE
WR | ADA
SRE
A0 • ADA | D0
OUTPUT • WR
0
0
D0 INPUT
–
Note: 1. ADA is short for ADdress Active and represents the time when address is output. See
“External Memory Interface” on page 25 for details.
Alternate Functions of Port B The Port B pins with alternate functions are shown in Table 30.
Table 30. Port B Pins Alternate Functions
Port Pin
PB7
Alternate Functions
OC2/OC1C(1) (Output Compare and PWM Output for Timer/Counter2 or Output
Compare and PWM Output C for Timer/Counter1)
PB6 OC1B (Output Compare and PWM Output B for Timer/Counter1)
PB5 OC1A (Output Compare and PWM Output A for Timer/Counter1)
PB4 OC0 (Output Compare and PWM Output for Timer/Counter0)
PB3 MISO (SPI Bus Master Input/Slave Output)
PB2 MOSI (SPI Bus Master Output/Slave Input)
PB1 SCK (SPI Bus Serial Clock)
PB0 SS (SPI Slave Select input)
Note: 1. OC1C not applicable in ATmega103 compatibility mode.
The alternate pin configuration is as follows:
• OC2/OC1C, Bit 7
OC2, Output Compare Match output: The PB7 pin can serve as an external output for
the Timer/Counter2 Output Compare. The pin has to be configured as an output (DDB7
set (one)) to serve this function. The OC2 pin is also the output pin for the PWM mode
timer function.
OC1C, Output Compare Match C output: The PB7 pin can serve as an external output
for the Timer/Counter1 Output Compare C. The pin has to be configured as an output
(DDB7 set (one)) to serve this function. The OC1C pin is also the output pin for the
PWM mode timer function.
72 ATmega64(L)
2490G–AVR–03/04