ATmega169P
12.3 Alternate Port Functions
Most port pins have alternate functions in addition to being general digital I/Os. Figure 12-5
shows how the port pin control signals from the simplified Figure 12-2 can be overridden by
alternate functions. The overriding signals may not be present in all port pins, but the figure
serves as a generic description applicable to all port pins in the AVR microcontroller family.
Figure 12-5. Alternate Port Functions(1)
PUOExn
PUOVxn
1
PUD
0
DDOExn
DDOVxn
1
Q
D
0
DDxn
Q CLR
WDx
RDx
PVOExn
PVOVxn
RESET
1
0
1
0
Pxn
Q
D
PORTxn
PTOExn
WPx
Q CLR
DIEOExn
DIEOVxn
SLEEP
RESET
WRx
1
0
RRx
RPx
SYNCHRONIZER
SET
D
Q
D
L
Q
Q
PINxn
CLR Q
CLR
clk I/O
DIxn
AIOxn
PUOExn: Pxn PULL-UP OVERRIDE ENABLE
PUOVxn: Pxn PULL-UP OVERRIDE VALUE
DDOExn: Pxn DATA DIRECTION OVERRIDE ENABLE
DDOVxn: Pxn DATA DIRECTION OVERRIDE VALUE
PVOExn: Pxn PORT VALUE OVERRIDE ENABLE
PVOVxn: Pxn PORT VALUE OVERRIDE VALUE
PUD:
WDx:
RDx:
RRx:
WRx:
RPx:
WPx:
PULLUP DISABLE
WRITE DDRx
READ DDRx
READ PORTx REGISTER
WRITE PORTx
READ PORTx PIN
WRITE PINx
I/O CLOCK
DIGITAL INPUT PIN n ON PORTx
ANALOG INPUT/OUTPUT PIN n ON PORTx
DIEOExn: Pxn DIGITAL INPUT-ENABLE OVERRIDE ENABLE
DIEOVxn: Pxn DIGITAL INPUT-ENABLE OVERRIDE VALUE
clkI/O
DIxn:
AIOxn:
:
SLEEP:
SLEEP CONTROL
PTOExn: Pxn, PORT TOGGLE OVERRIDE ENABLE
Note:
1. WRx, WPx, WDx, RRx, RPx, and RDx are common to all pins within the same port. clkI/O
,
SLEEP, and PUD are common to all ports. All other signals are unique for each pin.
Table 12-2 on page 72 summarizes the function of the overriding signals. The pin and port
indexes from Figure 12-5 on page 71 are not shown in the succeeding tables. The overriding
signals are generated internally in the modules having the alternate function.
71
8018A–AVR–03/06
ATMEL [ ATMEL ]
