Special function io register – sfior, Alternate functions of port a, Atmega162/v – Rainbow Electronics ATmega162V User Manual
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ATmega162/V
2513E–AVR–09/03
Special Function IO Register –
SFIOR
• Bit 2 – PUD: Pull-up Disable
When this bit is written to one, the pull-ups in the I/O ports are disabled even if the DDxn
and PORTxn Registers are configured to enable the pull-ups ({DDxn, PORTxn} = 0b01).
See “Configuring the Pin” on page 63 for more details about this feature.
Alternate Functions of Port A
Port A has an alternate function as the address low byte and data lines for the External
Memory Interface and as Pin Change Interrupt.
Table 30 and Table 31 relate the alternate functions of Port A to the overriding signals
shown in Figure 32 on page 67.
Bit
7
6
5
4
3
2
1
0
TSM
XMBK
XMM2
XMM1
XMM0
PUD
PSR2
PSR310
SFIOR
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Table 29. Port A Pins Alternate Functions
Port Pin
Alternate Function
PA7
AD7 (External memory interface address and data bit 7)
PCINT7 (Pin Change INTerrupt 7)
PA6
AD6 (External memory interface address and data bit 6)
PCINT6 (Pin Change INTerrupt 6)
PA5
AD5 (External memory interface address and data bit 5)
PCINT5 (Pin Change INTerrupt 5)
PA4
AD4 (External memory interface address and data bit 4)
PCINT4 (Pin Change INTerrupt 4)
PA3
AD3 (External memory interface address and data bit 3)
PCINT3 (Pin Change INTerrupt 3)
PA2
AD2 (External memory interface address and data bit 2)
PCINT2 (Pin Change INTerrupt 2)
PA1
AD1 (External memory interface address and data bit 1)
PCINT1 (Pin Change INTerrupt 1)
PA0
AD0 (External memory interface address and data bit 0)
PCINT0 (Pin Change INTerrupt 0)