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- /*
- || @author Paul Stoffregen (paul at pjrc dot com)
- || @contribution Brett Hagman <bhagman@wiring.org.co>
- || @url http://wiring.org.co/
- ||
- || @description
- || | A Software PWM Library
- || |
- || | Simple timer abstractions.
- || #
- ||
- || @license Please see the accompanying LICENSE.txt file for this project.
- ||
- || @name Software PWM Library support
- || @type Library support
- || @target Atmel AVR 8 Bit
- ||
- || @version 1.0.0
- ||
- */
-
- #include <avr/io.h>
- #include <avr/interrupt.h>
-
- // allow certain chips to use different timers
- #if defined(__AVR_ATmega32U4__)
- #define USE_TIMER4_HS // Teensy 2.0 lacks timer2, but has high speed timer4 :-)
- #elif defined(__arm__) && defined(TEENSYDUINO)
- #define USE_INTERVALTIMER // Teensy 3.x has special interval timers :-)
- #else
- #define USE_TIMER2
- #endif
-
- // for each timer, these macros define how to actually use it
- #if defined(USE_TIMER2)
- #define SOFTPWM_TIMER_INTERRUPT TIMER2_COMPA_vect
- #define SOFTPWM_TIMER_SET(val) (TCNT2 = (val))
- #define SOFTPWM_TIMER_INIT(ocr) ({\
- TIFR2 = (1 << TOV2); /* clear interrupt flag */ \
- TCCR2B = (1 << CS21); /* start timer (ck/8 prescalar) */ \
- TCCR2A = (1 << WGM21); /* CTC mode */ \
- OCR2A = (ocr); /* We want to have at least 30Hz or else it gets choppy */ \
- TIMSK2 = (1 << OCIE2A); /* enable timer2 output compare match interrupt */ \
- })
- #elif defined(USE_TIMER4_HS)
- #define SOFTPWM_TIMER_INTERRUPT TIMER4_COMPA_vect
- #define SOFTPWM_TIMER_SET(val) (TCNT4 = (val))
- #define SOFTPWM_TIMER_INIT(ocr) ({\
- TCCR4A = 0; \
- TCCR4B = 0x04; /* CTC Mode */\
- TCCR4C = 0; \
- TCCR4D = 0; \
- TCCR4E = 0; \
- OCR4C = 0; \
- OCR4C = (ocr); \
- TIMSK4 = (1 << OCIE4A); \
- })
- #elif defined(USE_INTERVALTIMER)
- #define SOFTPWM_TIMER_INTERRUPT softpwm_interval_timer
- #ifdef ISR
- #undef ISR
- #endif
- #define ISR(f) void f(void)
- #define SOFTPWM_TIMER_SET(val)
- #define SOFTPWM_TIMER_INIT(ocr) ({\
- IntervalTimer *t = new IntervalTimer(); \
- t->begin(softpwm_interval_timer, 1000000.0 / (float)(SOFTPWM_FREQ * 256)); \
- })
- #endif
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