ATmega163(L)
101
The Port B pins with alternate functions are shown in Table 44.
When the pins are used for the alternate function, the DDRB and PORTB registers have to be set according to the alternate
function description.
The Port B Data Register - PORTB
The Port B Data Direction Register - DDRB
The Port B Input Pins Address - PINB
The Port B Input Pins address - PINB - is not a register, and this address enables access to the physical value on each Port
B pin. When reading PORTB, the PORTB Data Latch is read, and when reading PINB, the logical values present on the
pins are read.
Port B As General Digital I/O
All 8 bits in Port B are equal when used as digital I/O pins. PBn, General I/O pin: The DDBn bit in the DDRB register selects
the direction of this pin, if DDBn is set (one), PBn is configured as an output pin. If DDBn is cleared (zero), PBn is config-
ured as an input pin. If PORTBn is set (one) when the pin configured as an input pin, the MOS pull up resistor is activated.
To switch the pull up resistor off, the PORTBn has to be cleared (zero), the pin has to be configured as an output pin, or the
PUD bit has to be set. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running.
Table 44. Port B Pins Alternate Functions
Port Pin Alternate Functions
PB0 T0 (Timer/Counter 0 External Counter Input)
PB1 T1 (Timer/Counter 1 External Counter Input)
PB2 AIN0 (Analog Comparator Positive Input)
PB3 AIN1 (Analog Comparator Negative Input)
PB4 SS
(SPI Slave Select Input)
PB5 MOSI (SPI Bus Master Output/Slave Input)
PB6 MISO (SPI Bus Master Input/Slave Output)
PB7 SCK (SPI Bus Serial Clock)
Bit 76543210
$18 ($38) PORTB7 PORTB6 PORTB5 PORTB4 PORTB3 PORTB2 PORTB1 PORTB0 PORTB
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial value00000000
Bit 76543210
$17 ($37) DDB7 DDB6 DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 DDRB
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial value00000000
Bit 76543210
$16 ($36) PINB7 PINB6 PINB5 PINB4 PINB3 PINB2 PINB1 PINB0 PINB
Read/Write RRRRRRRR
Initial value N/A N/A N/A N/A N/A N/A N/A N/A
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