diff options
Diffstat (limited to 'core/wiring.c')
| -rwxr-xr-x | core/wiring.c | 250 |
1 files changed, 0 insertions, 250 deletions
diff --git a/core/wiring.c b/core/wiring.c deleted file mode 100755 index 72bc282..0000000 --- a/core/wiring.c +++ /dev/null @@ -1,250 +0,0 @@ -/* - wiring.c - Partial implementation of the Wiring API for the ATmega8. - Part of Arduino - http://www.arduino.cc/ - - Copyright (c) 2005-2006 David A. Mellis - - This library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - This library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General - Public License along with this library; if not, write to the - Free Software Foundation, Inc., 59 Temple Place, Suite 330, - Boston, MA 02111-1307 USA - - $Id$ -*/ - -#include "wiring_private.h" - -// the prescaler is set so that timer0 ticks every 64 clock cycles, and the -// the overflow handler is called every 256 ticks. -#define MICROSECONDS_PER_TIMER0_OVERFLOW (clockCyclesToMicroseconds(64 * 256)) - -// the whole number of milliseconds per timer0 overflow -#define MILLIS_INC (MICROSECONDS_PER_TIMER0_OVERFLOW / 1000) - -// the fractional number of milliseconds per timer0 overflow. we shift right -// by three to fit these numbers into a byte. (for the clock speeds we care -// about - 8 and 16 MHz - this doesn't lose precision.) -#define FRACT_INC ((MICROSECONDS_PER_TIMER0_OVERFLOW % 1000) >> 3) -#define FRACT_MAX (1000 >> 3) - -volatile unsigned long timer0_overflow_count = 0; -volatile unsigned long timer0_millis = 0; -static unsigned char timer0_fract = 0; - -SIGNAL(TIMER0_OVF_vect) -{ - // copy these to local variables so they can be stored in registers - // (volatile variables must be read from memory on every access) - unsigned long m = timer0_millis; - unsigned char f = timer0_fract; - - m += MILLIS_INC; - f += FRACT_INC; - if (f >= FRACT_MAX) { - f -= FRACT_MAX; - m += 1; - } - - timer0_fract = f; - timer0_millis = m; - timer0_overflow_count++; -} - -unsigned long millis() -{ - unsigned long m; - uint8_t oldSREG = SREG; - - // disable interrupts while we read timer0_millis or we might get an - // inconsistent value (e.g. in the middle of a write to timer0_millis) - cli(); - m = timer0_millis; - SREG = oldSREG; - - return m; -} - -unsigned long micros() { - unsigned long m, t; - uint8_t oldSREG = SREG; - - cli(); - t = TCNT0; - -#ifdef TIFR0 - if ((TIFR0 & _BV(TOV0)) && (t == 0)) - t = 256; -#else - if ((TIFR & _BV(TOV0)) && (t == 0)) - t = 256; -#endif - - m = timer0_overflow_count; - SREG = oldSREG; - - return ((m << 8) + t) * (64 / clockCyclesPerMicrosecond()); -} - -void delay(unsigned long ms) -{ - unsigned long start = millis(); - - while (millis() - start <= ms) - ; -} - -/* Delay for the given number of microseconds. Assumes a 8 or 16 MHz clock. - * Disables interrupts, which will disrupt the millis() function if used - * too frequently. */ -void delayMicroseconds(unsigned int us) -{ - uint8_t oldSREG; - - // calling avrlib's delay_us() function with low values (e.g. 1 or - // 2 microseconds) gives delays longer than desired. - //delay_us(us); - -#if F_CPU >= 16000000L - // for the 16 MHz clock on most Arduino boards - - // for a one-microsecond delay, simply return. the overhead - // of the function call yields a delay of approximately 1 1/8 us. - if (--us == 0) - return; - - // the following loop takes a quarter of a microsecond (4 cycles) - // per iteration, so execute it four times for each microsecond of - // delay requested. - us <<= 2; - - // account for the time taken in the preceeding commands. - us -= 2; -#else - // for the 8 MHz internal clock on the ATmega168 - - // for a one- or two-microsecond delay, simply return. the overhead of - // the function calls takes more than two microseconds. can't just - // subtract two, since us is unsigned; we'd overflow. - if (--us == 0) - return; - if (--us == 0) - return; - - // the following loop takes half of a microsecond (4 cycles) - // per iteration, so execute it twice for each microsecond of - // delay requested. - us <<= 1; - - // partially compensate for the time taken by the preceeding commands. - // we can't subtract any more than this or we'd overflow w/ small delays. - us--; -#endif - - // disable interrupts, otherwise the timer 0 overflow interrupt that - // tracks milliseconds will make us delay longer than we want. - oldSREG = SREG; - cli(); - - // busy wait - __asm__ __volatile__ ( - "1: sbiw %0,1" "\n\t" // 2 cycles - "brne 1b" : "=w" (us) : "0" (us) // 2 cycles - ); - - // reenable interrupts. - SREG = oldSREG; -} - -void init() -{ - // this needs to be called before setup() or some functions won't - // work there - sei(); - - // on the ATmega168, timer 0 is also used for fast hardware pwm - // (using phase-correct PWM would mean that timer 0 overflowed half as often - // resulting in different millis() behavior on the ATmega8 and ATmega168) -#if !defined(__AVR_ATmega8__) - sbi(TCCR0A, WGM01); - sbi(TCCR0A, WGM00); -#endif - // set timer 0 prescale factor to 64 -#if defined(__AVR_ATmega8__) - sbi(TCCR0, CS01); - sbi(TCCR0, CS00); -#else - sbi(TCCR0B, CS01); - sbi(TCCR0B, CS00); -#endif - // enable timer 0 overflow interrupt -#if defined(__AVR_ATmega8__) - sbi(TIMSK, TOIE0); -#else - sbi(TIMSK0, TOIE0); -#endif - - // timers 1 and 2 are used for phase-correct hardware pwm - // this is better for motors as it ensures an even waveform - // note, however, that fast pwm mode can achieve a frequency of up - // 8 MHz (with a 16 MHz clock) at 50% duty cycle - - // set timer 1 prescale factor to 64 - sbi(TCCR1B, CS11); - sbi(TCCR1B, CS10); - // put timer 1 in 8-bit phase correct pwm mode - sbi(TCCR1A, WGM10); - - // set timer 2 prescale factor to 64 -#if defined(__AVR_ATmega8__) - sbi(TCCR2, CS22); -#else - sbi(TCCR2B, CS22); -#endif - // configure timer 2 for phase correct pwm (8-bit) -#if defined(__AVR_ATmega8__) - sbi(TCCR2, WGM20); -#else - sbi(TCCR2A, WGM20); -#endif - -#if defined(__AVR_ATmega1280__) - // set timer 3, 4, 5 prescale factor to 64 - sbi(TCCR3B, CS31); sbi(TCCR3B, CS30); - sbi(TCCR4B, CS41); sbi(TCCR4B, CS40); - sbi(TCCR5B, CS51); sbi(TCCR5B, CS50); - // put timer 3, 4, 5 in 8-bit phase correct pwm mode - sbi(TCCR3A, WGM30); - sbi(TCCR4A, WGM40); - sbi(TCCR5A, WGM50); -#endif - - // set a2d prescale factor to 128 - // 16 MHz / 128 = 125 KHz, inside the desired 50-200 KHz range. - // XXX: this will not work properly for other clock speeds, and - // this code should use F_CPU to determine the prescale factor. - sbi(ADCSRA, ADPS2); - sbi(ADCSRA, ADPS1); - sbi(ADCSRA, ADPS0); - - // enable a2d conversions - sbi(ADCSRA, ADEN); - - // the bootloader connects pins 0 and 1 to the USART; disconnect them - // here so they can be used as normal digital i/o; they will be - // reconnected in Serial.begin() -#if defined(__AVR_ATmega8__) - UCSRB = 0; -#else - UCSR0B = 0; -#endif -}
\ No newline at end of file |