atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 61

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

9.2
9.2.1
7647A–AVR–02/08
Ports as General Digital I/O
Configuring the Pin
The ports are bi-directional I/O ports with optional internal pull-ups.
tional description of one I/O-port pin, here generically called Pxn.
Figure 9-2.
Note:
Each port pin consists of three register bits: DDxn, PORTxn, and PINxn. As shown in
Description for I/O-Ports” on page
PORTxn bits at the PORTx I/O address, and the PINxn bits at the PINx I/O address.
The DDxn bit in the DDRx Register selects the direction of this pin. If DDxn is written logic one,
Pxn is configured as an output pin. If DDxn is written logic zero, Pxn is configured as an input
pin.
If PORTxn is written logic one when the pin is configured as an input pin, the pull-up resistor is
activated. To switch the pull-up resistor off, PORTxn has to be written logic zero or the pin has to
be configured as an output pin
The port pins are tri-stated when reset condition becomes active, even if no clocks are running.
1. WRx, WPx, WDx, RRx, RPx, and RDx are common to all pins within the same port. clk
Pxn
SLEEP, and PUD are common to all ports.
General Digital I/O
SLEEP: SLEEP CONTROL
clk
PUD: PULLUP DISABLE
I/O
: I/O CLOCK
(1)
79, the DDxn bits are accessed at the DDRx I/O address, the
SLEEP
SYNCHRONIZER
ATmega32/64/M1/C1
WDx: WRITE DDRx
RDx: READ DDRx
WRx: WRITE PORTx
RRx: READ PORTx REGISTER
RPx: READ PORTx PIN
WPx: WRITE PINx REGISTER
D
L
Q
Q
D
PINxn
Q
Q
Figure 9-2
RESET
RESET
PORTxn
Q
Q
Q
Q
DDxn
CLR
CLR
D
D
RRx
shows a func-
PUD
clk
WDx
RDx
RPx
1
0
I/O
“Register
WPx
WRx
I/O
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