78
2467S–AVR–07/09
ATmega128
Note:
1. XMM = 0 in ATmega103 compatibility mode.
Alternate Functions of
Port D
The Port D pins with alternate functions are shown in
Note:
1. XCK1, TXD1, RXD1, SDA, and SCL not applicable in ATmega103 compatibility mode.
The alternate pin configuration is as follows:
• T2 – Port D, Bit 7
T2, Timer/Counter2 counter source.
• T1 – Port D, Bit 6
T1, Timer/Counter1 counter source.
• XCK1 – Port D, Bit 5
XCK1, USART1 External clock. The Data Direction Register (DDD4) controls whether the clock
is output (DDD4 set) or input (DDD4 cleared). The XCK1 pin is active only when the USART1
operates in Synchronous mode.
Table 35.
Overriding Signals for Alternate Functions in PC3..PC0
Signal
Name
PC3/A11
PC2/A10
PC1/A9
PC0/A8
PUOE
SRE • (XMM<5)
SRE • (XMM<6)
SRE • (XMM<7)
SRE • (XMM<7)
PUOV
0
0
0
0
DDOE
SRE • (XMM<5)
SRE • (XMM<6)
SRE • (XMM<7)
SRE • (XMM<7)
DDOV
1
1
1
1
PVOE
SRE • (XMM<5)
SRE • (XMM<6)
SRE • (XMM<7)
SRE • (XMM<7)
PVOV
A11
A10
A9
A8
DIEOE
0
0
0
0
DIEOV
0
0
0
0
DI
–
–
–
–
AIO
–
–
–
–
Table 36.
Port D Pins Alternate Functions
Port Pin
Alternate Function
PD7
T2 (Timer/Counter2 Clock Input)
PD6
T1 (Timer/Counter1 Clock Input)
PD5
XCK1
(USART1 External Clock Input/Output)
PD4
ICP1 (Timer/Counter1 Input Capture Pin)
PD3
(External Interrupt3 Input or UART1 Transmit Pin)
PD2
INT2/RXD1
(External Interrupt2 Input or UART1 Receive Pin)
PD1
INT1/SDA
(External Interrupt1 Input or TWI Serial DAta)
PD0
(External Interrupt0 Input or TWI Serial CLock)