ATMEGA48V_11 ATMEL [ATMEL Corporation], ATMEGA48V_11 Datasheet - Page 76

• Manufacturer Part Number: ATMEGA48V_11
• Description: 8-bit Atmel Microcontroller with 4/8/16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

14.3
2545T–AVR–05/11
Alternate port functions
ing inputs should be avoided to reduce current consumption in all other modes where the digital
inputs are enabled (Reset, Active mode and Idle mode).
The simplest method to ensure a defined level of an unused pin, is to enable the internal pull-up.
In this case, the pull-up will be disabled during reset. If low power consumption during reset is
important, it is recommended to use an external pull-up or pull-down. Connecting unused pins
directly to V
accidentally configured as an output.
Most port pins have alternate functions in addition to being general digital I/Os.
shows how the port pin control signals from the simplified
ridden 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 14-5. Alternate port functions
Note:
PTOExn:
PUOExn:
PUOVxn:
DDOExn:
DDOVxn:
PVOExn:
PVOVxn:
DIEOExn: Pxn DIGITAL INPUT-ENABLE OVERRIDE ENABLE
DIEOVxn: Pxn DIGITAL INPUT-ENABLE OVERRIDE VALUE
SLEEP:
Pxn
1. WRx, WPx, WDx, RRx, RPx, and RDx are common to all pins within the same port. clk
SLEEP, and PUD are common to all ports. All other signals are unique for each pin.
CC
Pxn PULL-UP OVERRIDE ENABLE
Pxn PULL-UP OVERRIDE VALUE
Pxn DATA DIRECTION OVERRIDE ENABLE
Pxn DATA DIRECTION OVERRIDE VALUE
Pxn PORT VALUE OVERRIDE ENABLE
Pxn PORT VALUE OVERRIDE VALUE
SLEEP CONTROL
Pxn, PORT TOGGLE OVERRIDE ENABLE
or GND is not recommended, since this may cause excessive currents if the pin is
1
0
1
0
1
0
1
0
(1)
PUOExn
PUOVxn
DIEOExn
DDOExn
DDOVxn
PVOExn
PVOVxn
DIEOVxn
SLEEP
.
PUD:
WDx:
RDx:
RRx:
WRx:
RPx:
WPx:
clk
DIxn:
AIOxn:
SYNCHRONIZER
D
L
I/O
SET
CLR
:
Q
Q
WRITE DDRx
WRITE PORTx
PULLUP DISABLE
READ DDRx
READ PORTx REGISTER
READ PORTx PIN
WRITE PINx
I/O CLOCK
DIGITAL INPUT PIN n ON PORTx
ANALOG INPUT/OUTPUT PIN n ON PORTx
D
PINxn
CLR
Q
Q
Figure 14-2 on page 72
RESET
RESET
PORTxn
Q
Q
Q
Q
DDxn
CLR
CLR
D
D
ATmega48/88/168
1
0
clk
PUD
WDx
RRx
DIxn
AIOxn
RDx
RPx
I/O
WRx
PTOExn
WPx
can be over-
Figure 14-5
I/O
,
76