From abedda49627fac68620aa62372231537dbd36e64 Mon Sep 17 00:00:00 2001 From: Vasilis Georgitzikis Date: Sun, 15 Feb 2015 19:08:13 +0200 Subject: [PATCH] Created wiring.c with the 12MHz Ray (from Ray's Hobby Shop) has issued a fix for delayMicroseconds() which makes it work with 12MHz boards. It's also an important fix for Adafruit's Pro Trinket 3v3 which run at 12MHz. Since it's in the core, I've added it here --- override_cores/arduino/wiring.c | 382 ++++++++++++++++++++++++++++++++ 1 file changed, 382 insertions(+) create mode 100644 override_cores/arduino/wiring.c diff --git a/override_cores/arduino/wiring.c b/override_cores/arduino/wiring.c new file mode 100644 index 0000000..3650c41 --- /dev/null +++ b/override_cores/arduino/wiring.c @@ -0,0 +1,382 @@ +/* + 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; + +#if defined(__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__) +ISR(TIM0_OVF_vect) +#else +ISR(TIMER0_OVF_vect) +#endif +{ + // 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; + uint8_t oldSREG = SREG, t; + + cli(); + m = timer0_overflow_count; +#if defined(TCNT0) + t = TCNT0; +#elif defined(TCNT0L) + t = TCNT0L; +#else + #error TIMER 0 not defined +#endif + + +#ifdef TIFR0 + if ((TIFR0 & _BV(TOV0)) && (t < 255)) + m++; +#else + if ((TIFR & _BV(TOV0)) && (t < 255)) + m++; +#endif + + SREG = oldSREG; + + return ((m << 8) + t) * (64 / clockCyclesPerMicrosecond()); +} + +void delay(unsigned long ms) +{ + uint16_t start = (uint16_t)micros(); + + while (ms > 0) { + if (((uint16_t)micros() - start) >= 1000) { + ms--; + start += 1000; + } + } +} + +/* Delay for the given number of microseconds. Assumes a 1, 8, 12, 16, 20 or 24 MHz clock. */ +void delayMicroseconds(unsigned int us) +{ + // call = 4 cycles + 2 to 4 cycles to init us(2 for constant delay, 4 for variable) + // 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 >= 24000000L + // for the 24 MHz clock for the aventurous ones, trying to overclock + + // for a one-microsecond delay, simply wait 6 cycles and return. The overhead + // of the function call yields a delay of exactly one microsecond. + __asm__ __volatile__ ( + "nop" "\n\t" + "nop" "\n\t" + "nop" "\n\t" + "nop" "\n\t" + "nop" "\n\t" + "nop"); //just waiting 6 cycles + if (--us == 0) + return; + + // the following loop takes a 1/6 of a microsecond (4 cycles) + // per iteration, so execute it six times for each microsecond of + // delay requested. + us *= 6; // x6 us + + // account for the time taken in the preceeding commands. + us -= 2; + +#elif F_CPU >= 20000000L + // for the 20 MHz clock on rare Arduino boards + + // for a one-microsecond delay, simply wait 2 cycles and return. The overhead + // of the function call yields a delay of exactly one microsecond. + __asm__ __volatile__ ( + "nop" "\n\t" + "nop"); //just waiting 2 cycle + if (--us == 0) + return; + + // the following loop takes a 1/5 of a microsecond (4 cycles) + // per iteration, so execute it five times for each microsecond of + // delay requested. + us = (us<<2) + us; // x5 us + + // account for the time taken in the preceeding commands. + us -= 2; + +#elif 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 1/4 of a microsecond (4 cycles) + // per iteration, so execute it four times for each microsecond of + // delay requested. + us <<= 2; // x4 us + + // account for the time taken in the preceeding commands. + us -= 2; + +#elif F_CPU >= 12000000L + // for the 12 MHz clock if somebody is working with USB + + // for a one-microsecond delay, simply return. the overhead + // of the function call yields a delay of approximately 1.5 us. + if (--us == 0) + return; + + // the following loop takes 1/3 of a microsecond (4 cycles) + // per iteration, so execute it three times for each microsecond of + // delay requested. + us = (us << 1) + us; // x3 us + + // account for the time taken in the preceeding commands. + us -= 2; +#elif F_CPU >= 8000000L + // for the 8 MHz internal clock + + // 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 1/2 of a microsecond (4 cycles) + // per iteration, so execute it twice for each microsecond of + // delay requested. + us <<= 1; //x2 us + + // 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--; + +#else + // for the 1 MHz internal clock (default settings for common Atmega microcontrollers) + + // the overhead of the function calls takes about 16 microseconds. + if (us <= 16) //4 cycles spent here + return; + if (us <= 22) { //4 cycles spent here + return; + } + + // compensate for the time taken by the preceeding and next commands. + us -= 22; + + // the following loop takes 4 microseconds (4 cycles) + // per iteration, so execute it us/4 times + us >>= 2; // us div 4 +#endif + + // busy wait + __asm__ __volatile__ ( + "1: sbiw %0,1" "\n\t" // 2 cycles + "brne 1b" : "=w" (us) : "0" (us) // 2 cycles + ); + // return = 4 cycles +} + +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(TCCR0A) && defined(WGM01) + sbi(TCCR0A, WGM01); + sbi(TCCR0A, WGM00); +#endif + + // set timer 0 prescale factor to 64 +#if defined(__AVR_ATmega128__) + // CPU specific: different values for the ATmega128 + sbi(TCCR0, CS02); +#elif defined(TCCR0) && defined(CS01) && defined(CS00) + // this combination is for the standard atmega8 + sbi(TCCR0, CS01); + sbi(TCCR0, CS00); +#elif defined(TCCR0B) && defined(CS01) && defined(CS00) + // this combination is for the standard 168/328/1280/2560 + sbi(TCCR0B, CS01); + sbi(TCCR0B, CS00); +#elif defined(TCCR0A) && defined(CS01) && defined(CS00) + // this combination is for the __AVR_ATmega645__ series + sbi(TCCR0A, CS01); + sbi(TCCR0A, CS00); +#else + #error Timer 0 prescale factor 64 not set correctly +#endif + + // enable timer 0 overflow interrupt +#if defined(TIMSK) && defined(TOIE0) + sbi(TIMSK, TOIE0); +#elif defined(TIMSK0) && defined(TOIE0) + sbi(TIMSK0, TOIE0); +#else + #error Timer 0 overflow interrupt not set correctly +#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 + +#if defined(TCCR1B) && defined(CS11) && defined(CS10) + TCCR1B = 0; + + // set timer 1 prescale factor to 64 + sbi(TCCR1B, CS11); +#if F_CPU >= 8000000L + sbi(TCCR1B, CS10); +#endif +#elif defined(TCCR1) && defined(CS11) && defined(CS10) + sbi(TCCR1, CS11); +#if F_CPU >= 8000000L + sbi(TCCR1, CS10); +#endif +#endif + // put timer 1 in 8-bit phase correct pwm mode +#if defined(TCCR1A) && defined(WGM10) + sbi(TCCR1A, WGM10); +#elif defined(TCCR1) + #warning this needs to be finished +#endif + + // set timer 2 prescale factor to 64 +#if defined(TCCR2) && defined(CS22) + sbi(TCCR2, CS22); +#elif defined(TCCR2B) && defined(CS22) + sbi(TCCR2B, CS22); +#else + #warning Timer 2 not finished (may not be present on this CPU) +#endif + + // configure timer 2 for phase correct pwm (8-bit) +#if defined(TCCR2) && defined(WGM20) + sbi(TCCR2, WGM20); +#elif defined(TCCR2A) && defined(WGM20) + sbi(TCCR2A, WGM20); +#else + #warning Timer 2 not finished (may not be present on this CPU) +#endif + +#if defined(TCCR3B) && defined(CS31) && defined(WGM30) + sbi(TCCR3B, CS31); // set timer 3 prescale factor to 64 + sbi(TCCR3B, CS30); + sbi(TCCR3A, WGM30); // put timer 3 in 8-bit phase correct pwm mode +#endif + +#if defined(TCCR4A) && defined(TCCR4B) && defined(TCCR4D) /* beginning of timer4 block for 32U4 and similar */ + sbi(TCCR4B, CS42); // set timer4 prescale factor to 64 + sbi(TCCR4B, CS41); + sbi(TCCR4B, CS40); + sbi(TCCR4D, WGM40); // put timer 4 in phase- and frequency-correct PWM mode + sbi(TCCR4A, PWM4A); // enable PWM mode for comparator OCR4A + sbi(TCCR4C, PWM4D); // enable PWM mode for comparator OCR4D +#else /* beginning of timer4 block for ATMEGA1280 and ATMEGA2560 */ +#if defined(TCCR4B) && defined(CS41) && defined(WGM40) + sbi(TCCR4B, CS41); // set timer 4 prescale factor to 64 + sbi(TCCR4B, CS40); + sbi(TCCR4A, WGM40); // put timer 4 in 8-bit phase correct pwm mode +#endif +#endif /* end timer4 block for ATMEGA1280/2560 and similar */ + +#if defined(TCCR5B) && defined(CS51) && defined(WGM50) + sbi(TCCR5B, CS51); // set timer 5 prescale factor to 64 + sbi(TCCR5B, CS50); + sbi(TCCR5A, WGM50); // put timer 5 in 8-bit phase correct pwm mode +#endif + +#if defined(ADCSRA) + // 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); +#endif + + // 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(UCSRB) + UCSRB = 0; +#elif defined(UCSR0B) + UCSR0B = 0; +#endif +}