Rainbow-electronics ATmega103L Uživatelský manuál stáhnout pdf (Strana 77)

ATmega603/103

The Port B pins with alternate functions are shown in the following table:

When the pins are used for the alternate function the DDRB and PORTB register have to be set according to the alternate

function description.

Port B Data Register - PORTB

Port B Data Direction Register - DDRB

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 Port B 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 pins in port B have equal functionality 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 con-

figured as an output pin. If DDBn is cleared (zero), PBn is configured 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) or the pin has to be configured as an output pin. The port pins are tri-stated when a reset condition becomes

active, even if the clock is not running.

Table 30. Port B Pins Alternate Functions

Port Pin Alternate Functions

PB0 SS

(SPI Slave Select input)

PB1 SCK (SPI Bus Serial Clock)

PB2 MOSI (SPI Bus Master Output/Slave Input)

PB3 MISO (SPI Bus Master Input/Slave Output)

PB4 OC0/PWM0 (Output Compare and PWM Output for Timer/Counter0)

PB5 OC1A/PWM1A (Output Compare and PWM Output A for Timer/Counter1)

PB6 OC1B/PWM1B (Output Compare and PWM Output B for Timer/Counter1)

PB7 OC2/PWM2 (Output Compare and PWM Output for Timer/Counter2

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/WriteRRRRRRRR

Initial value Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z

1 2 ... 72 73 74 75 76 77 78 79 80 81 82 ... 125 126

Žádné komentáře

Rainbow-electronics ATmega103L Uživatelský manuál Strana 77