ATMEGA128-16AU SL383 Atmel, ATMEGA128-16AU SL383 Datasheet - Page 71

• Manufacturer Part Number: ATMEGA128-16AU SL383
• Manufacturer: Atmel

Unconnected pins
Alternate Port
Functions
2467S–AVR–07/09
If some pins are unused, it is recommended to ensure that these pins have a defined level. Even
though most of the digital inputs are disabled in the deep sleep modes as described above, float-
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.
how the port pin control signals from the simplified
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 33. Alternate Port Functions
Note:
1. WPx, WDx, RLx, RPx, and RDx are common to all pins within the same port. clk
and PUD are common to all ports. All other signals are unique for each pin.
PUOExn:
PUOVxn:
DDOExn:
DDOVxn:
PVOExn:
PVOVxn:
DIEOExn: Pxn DIGITAL INPUT-ENABLE OVERRIDE ENABLE
DIEOVxn: Pxn DIGITAL INPUT-ENABLE OVERRIDE VALUE
SLEEP:
CC
Pxn
or GND is not recommended, since this may cause excessive currents if the pin is
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
1
0
1
0
1
0
1
0
(1)
PUOExn
PUOVxn
DDOExn
DDOVxn
PVOExn
PVOVxn
DIEOExn
DIEOVxn
SLEEP
PUD:
WDx:
RDx:
RRx:
WPx:
RPx:
clk
DIxn:
AIOxn:
SYNCHRONIZER
D
L
Figure 30
I/O
SET
CLR
:
Q
Q
PULLUP DISABLE
WRITE DDRx
READ DDRx
READ PORTx REGISTER
WRITE PORTx
READ PORTx PIN
I/O CLOCK
DIGITAL INPUT PIN n ON PORTx
ANALOG INPUT/OUTPUT PIN n ON PORTx
D
PINxn
CLR
Q
Q
can be overridden by alternate
RESET
RESET
PORTxn
Q
Q
Q
Q
DDxn
CLR
CLR
D
D
ATmega128
clk
PUD
WDx
RDx
WPx
RRx
DIxn
AIOxn
RPx
I/O
Figure 33
I/O
, SLEEP,
shows
71