120 lines
3.1 KiB
C
120 lines
3.1 KiB
C
//tone04.c
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// use atmega timer4 as main tone timer instead of timer2
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// timer2 is used for System timer.
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#include "system_timer.h"
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#include "Configuration_var.h"
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#ifdef SYSTEM_TIMER_2
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#include "pins.h"
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#include "fastio.h"
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#include "macros.h"
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void timer4_init(void)
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{
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CRITICAL_SECTION_START;
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SET_OUTPUT(BEEPER);
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WRITE(BEEPER, LOW);
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SET_OUTPUT(EXTRUDER_0_AUTO_FAN_PIN);
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// Set timer mode 9 (PWM,Phase and Frequency Correct)
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// Prescaler is CLK/1024
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// Output compare is disabled on all timer pins
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// Input capture is disabled
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// All interrupts are disabled
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TCCR4A = _BV(WGM40);
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TCCR4B = _BV(WGM43) | _BV(CS42) | _BV(CS40);
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OCR4A = 255U;
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OCR4B = 255U;
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OCR4C = 255U;
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TIMSK4 = 0;
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CRITICAL_SECTION_END;
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}
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#ifdef EXTRUDER_0_AUTO_FAN_PIN
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void timer4_set_fan0(uint8_t duty)
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{
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if (duty == 0 || duty == 255)
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{
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// We use digital logic if the duty cycle is 0% or 100%
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TCCR4A &= ~_BV(COM4C1);
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OCR4C = 0;
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WRITE(EXTRUDER_0_AUTO_FAN_PIN, duty);
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}
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else
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{
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// Use the timer for fan speed. Enable the timer compare output and set the duty cycle.
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// This function also handles the impossible scenario of a fan speed change during a Tone.
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// Better be safe than sorry.
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CRITICAL_SECTION_START;
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// Enable the PWM output on the fan pin.
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TCCR4A |= _BV(COM4C1);
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OCR4C = (((uint16_t)duty) * ((uint16_t)((TIMSK4 & _BV(OCIE4A)) ? OCR4A : 255U))) / 255U;
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CRITICAL_SECTION_END;
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}
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}
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#endif //EXTRUDER_0_AUTO_FAN_PIN
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// Because of the timer mode change, we need two interrupts. We could also try to assume that the frequency is x2
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// and use a TOGGLE(), but this seems to work well enough so I left it as it is now.
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ISR(TIMER4_COMPA_vect)
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{
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WRITE(BEEPER, 1);
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}
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ISR(TIMER4_OVF_vect)
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{
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WRITE(BEEPER, 0);
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}
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void tone4(_UNUSED uint8_t _pin, uint16_t frequency)
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{
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//this ocr and prescalarbits calculation is taken from the Arduino core and simplified for one type of timer only
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uint8_t prescalarbits = 0b001;
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uint32_t pwm_freq = F_CPU / (2 * frequency);
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if (pwm_freq > UINT16_MAX) {
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pwm_freq /= 64; // Increase prescaler to 64
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prescalarbits = 0b011;
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}
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uint16_t ocr = pwm_freq - 1;
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CRITICAL_SECTION_START;
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// Set calcualted prescaler
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TCCR4B = (TCCR4B & 0b11111000) | prescalarbits;
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#ifdef EXTRUDER_0_AUTO_FAN_PIN
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// Scale the fan PWM duty cycle so that it remains constant, but at the tone frequency
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OCR4C = (OCR4C * ocr) / (uint16_t)((TIMSK4 & _BV(OCIE4A)) ? OCR4A : 255U);
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#endif //EXTRUDER_0_AUTO_FAN_PIN
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// Set calcualted ocr
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OCR4A = ocr;
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// Enable Output compare A interrupt and timer overflow interrupt
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TIMSK4 |= _BV(OCIE4A) | _BV(TOIE4);
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CRITICAL_SECTION_END;
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}
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void noTone4(_UNUSED uint8_t _pin)
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{
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CRITICAL_SECTION_START;
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// Revert prescaler to CLK/1024
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TCCR4B = (TCCR4B & 0b11111000) | _BV(CS42) | _BV(CS40);
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#ifdef EXTRUDER_0_AUTO_FAN_PIN
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// Scale the fan OCR back to the original value.
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OCR4C = (OCR4C * 255U) / (uint16_t)((TIMSK4 & _BV(OCIE4A)) ? OCR4A : 255U);
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#endif //EXTRUDER_0_AUTO_FAN_PIN
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OCR4A = 255U;
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// Disable Output compare A interrupt and timer overflow interrupt
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TIMSK4 &= ~(_BV(OCIE4A) | _BV(TOIE4));
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CRITICAL_SECTION_END;
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// Turn beeper off if it was on when noTone was called
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WRITE(BEEPER, 0);
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}
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#endif //SYSTEM_TIMER_2
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