Rainbow Electronics ATmega128RFA1 - Manual (Page 206)

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8266A-MCU Wireless-12/09
ATmega128RFA1
logic zero or the pin has to be configured as an output pin. If PORTBn is written logic
one when the pin is configured as an output pin, the port pin is driven high (one). If
PORTBn is written logic zero when the pin is configured as an output pin, the port pin is
driven low (zero).
• Bit 7:0 – PORTB7:0 - Port B Data Register Value
14.4.5 DDRB – Port B Data Direction Register
Bit 7 6 5 4 3 2 1 0
$04 ($24) DDB7 DDB6 DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 DDRB
Read/Write RW RW RW RW RW RW RW RW
Initial Value 0 0 0 0 0 0 0 0
The DDBn bit in the DDRB Register selects the direction of the PORTB pin n. If DDBn
is written logic one, PBn is configured as an output pin. If DDBn is written logic zero,
PBn is configured as an input pin.
• Bit 7:0 – DDB7:0 - Port B Data Direction Register Value
14.4.6 PINB – Port B Input Pins Address
Bit 7 6 5 4 3 2 1 0
$03 ($23) PINB7:0 PINB
Read/Write R R R R R R R R
Initial Value 0 0 0 0 0 0 0 0
This register allows access to the PORTB pins independent of the setting of the Data
Direction bit DDBn. The port pin can be read through the PINBn Register bit, and
writing a logic one to PINBn toggles the value of PORTBn.
• Bit 7:0 – PINB7:0 - Port B Input Pins Value
14.4.7 PORTD – Port D Data Register
Bit 7 6 5 4 3 2 1 0
$0B ($2B) PORTD7:0 PORTD
Read/Write RW RW RW RW RW RW RW RW
Initial Value 0 0 0 0 0 0 0 0
If PORTDn is written logic one when the PORTD pin n is configured as an input pin, the
pull-up resistor is activated. To switch the pull-up resistor off, PORTDn has to be written
logic zero or the pin has to be configured as an output pin. If PORTDn is written logic
one when the pin is configured as an output pin, the port pin is driven high (one). If
PORTDn is written logic zero when the pin is configured as an output pin, the port pin is
driven low (zero).
• Bit 7:0 – PORTD7:0 - Port D Data Register Value