/* pin = Arduino Mapped Pin Name, ex. Digital pin 22: pin = 22 */ void digitalWrite(uint8_t pin, uint8_t val) { uint8_t timer = digitalPinToTimer(pin); uint8_t bit = digitalPinToBitMask(pin); uint8_t port = digitalPinToPort(pin); volatile uint8_t *out; out = portOutputRegister(port); uint8_t oldSREG = SREG; cli(); if (val == LOW) { *out &= ~bit; } else { *out |= bit; } SREG = oldSREG; }
SREG (Status Register) und Globale Interrupts aktivieren: SREG -Register
extern const uint8_t PROGMEM digital_pin_to_port_PGM[]; #define digitalPinToPort(P) ( pgm_read_byte( digital_pin_to_port_PGM + (P) ) )
#define pgm_read_byte(address_short) pgm_read_byte_near(address_short) #define pgm_read_byte_near(address_short) __LPM((uint16_t)(address_short))
Was pgm_read_byte() macht bzw. wie es in Assembler übersetzt wird: Source von pgm_read_byte
C:\arduino-1.0.4\hardware\tools\avr\avr\include C:\arduino-1.0.4\hardware\arduino\cores\arduino
const uint16_t PROGMEM port_to_mode_PGM[] = { NOT_A_PORT, &DDRA, &DDRB, &DDRC, &DDRD, &DDRE, &DDRF, &DDRG, &DDRH, NOT_A_PORT, &DDRJ, &DDRK, &DDRL, };
/arduino/variants/mega/pins_arduino.h
Accessing data past 64k boundary on atmega1280