atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 68

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

10.3
68
Alternate Port Functions
ATmega32U4
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
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 10-5. Alternate Port Functions
Note:
PUOExn:
PUOVxn:
DDOExn:
DDOVxn:
PVOExn:
PVOVxn:
DIEOExn: Pxn DIGITAL INPUT-ENABLE OVERRIDE ENABLE
DIEOVxn: Pxn DIGITAL INPUT-ENABLE OVERRIDE VALUE
SLEEP:
PTOExn:
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, PORT TOGGLE OVERRIDE ENABLE
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
or GND is not recommended, since this may cause excessive currents if the pin is
1
0
1
0
1
0
1
0
PUOExn
PUOVxn
PVOExn
PVOVxn
DIEOExn
DIEOVxn
SLEEP
DDOExn
DDOVxn
(1)
SYNCHRONIZER
D
L
SET
CLR
Q
Q
PUD:
WDx:
RDx:
RRx:
WRx:
RPx:
WPx:
clk
DIxn:
AIOxn:
D
PINxn
CLR
I/O
Q
Q
:
RESET
PORTxn
Q
Q
CLR
D
RESET
Q
Q
DDxn
CLR
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
D
Figure 10-2
1
0
RRx
clk
PUD
WDx
RDx
DIxn
AIOxn
RPx
I/O
WRx
can be overridden by
PTOExn
WPx
7766A–AVR–03/08
Figure 10-5
I/O
,