marlin/Marlin/src/HAL/AVR/fast_pwm.cpp

/**
 * Marlin 3D Printer Firmware
 * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
 *
 * Based on Sprinter and grbl.
 * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */
#ifdef __AVR__

#include "../../inc/MarlinConfigPre.h"

#if NEEDS_HARDWARE_PWM // Specific meta-flag for features that mandate PWM

#include "HAL.h"

struct Timer {
  volatile uint8_t* TCCRnQ[3];  // max 3 TCCR registers per timer
  volatile uint16_t* OCRnQ[3];  // max 3 OCR registers per timer
  volatile uint16_t* ICRn;      // max 1 ICR register per timer
  uint8_t n;                    // the timer number [0->5]
  uint8_t q;                    // the timer output [0->2] (A->C)
};

/**
 * get_pwm_timer
 *  Get the timer information and register of the provided pin.
 *  Return a Timer struct containing this information.
 *  Used by set_pwm_frequency, set_pwm_duty
 */
Timer get_pwm_timer(const pin_t pin) {
  uint8_t q = 0;
  switch (digitalPinToTimer(pin)) {
    // Protect reserved timers (TIMER0 & TIMER1)
    #ifdef TCCR0A
      #if !AVR_AT90USB1286_FAMILY
        case TIMER0A:
      #endif
      case TIMER0B:
    #endif
    #ifdef TCCR1A
      case TIMER1A: case TIMER1B:
    #endif
                                        break;
    #if defined(TCCR2) || defined(TCCR2A)
      #ifdef TCCR2
        case TIMER2: {
          Timer timer = {
            /*TCCRnQ*/  { &TCCR2, nullptr, nullptr },
            /*OCRnQ*/   { (uint16_t*)&OCR2, nullptr, nullptr },
            /*ICRn*/      nullptr,
            /*n, q*/      2, 0
          };
        }
      #elif defined(TCCR2A)
        #if ENABLED(USE_OCR2A_AS_TOP)
          case TIMER2A:   break; // protect TIMER2A
          case TIMER2B: {
            Timer timer = {
              /*TCCRnQ*/  { &TCCR2A,  &TCCR2B,  nullptr },
              /*OCRnQ*/   { (uint16_t*)&OCR2A, (uint16_t*)&OCR2B, nullptr },
              /*ICRn*/      nullptr,
              /*n, q*/      2, 1
            };
            return timer;
          }
        #else
          case TIMER2B:   ++q;
          case TIMER2A: {
            Timer timer = {
              /*TCCRnQ*/  { &TCCR2A,  &TCCR2B,  nullptr },
              /*OCRnQ*/   { (uint16_t*)&OCR2A, (uint16_t*)&OCR2B, nullptr },
              /*ICRn*/      nullptr,
                            2, q
            };
            return timer;
          }
        #endif
      #endif
    #endif
    #ifdef OCR3C
      case TIMER3C:   ++q;
      case TIMER3B:   ++q;
      case TIMER3A: {
        Timer timer = {
          /*TCCRnQ*/  { &TCCR3A,  &TCCR3B,  &TCCR3C },
          /*OCRnQ*/   { &OCR3A,   &OCR3B,   &OCR3C },
          /*ICRn*/      &ICR3,
          /*n, q*/      3, q
        };
        return timer;
      }
    #elif defined(OCR3B)
      case TIMER3B:   ++q;
      case TIMER3A: {
        Timer timer = {
          /*TCCRnQ*/  { &TCCR3A,  &TCCR3B,  nullptr },
          /*OCRnQ*/   { &OCR3A,   &OCR3B,  nullptr },
          /*ICRn*/      &ICR3,
          /*n, q*/      3, q
        };
        return timer;
      }
    #endif
    #ifdef TCCR4A
      case TIMER4C:   ++q;
      case TIMER4B:   ++q;
      case TIMER4A: {
        Timer timer = {
          /*TCCRnQ*/  { &TCCR4A,  &TCCR4B,  &TCCR4C },
          /*OCRnQ*/   { &OCR4A,   &OCR4B,   &OCR4C },
          /*ICRn*/      &ICR4,
          /*n, q*/      4, q
        };
        return timer;
      }
    #endif
    #ifdef TCCR5A
      case TIMER5C:   ++q;
      case TIMER5B:   ++q;
      case TIMER5A: {
        Timer timer = {
          /*TCCRnQ*/  { &TCCR5A,  &TCCR5B,  &TCCR5C },
          /*OCRnQ*/   { &OCR5A,   &OCR5B,   &OCR5C },
          /*ICRn*/      &ICR5,
          /*n, q*/      5, q
        };
        return timer;
      }
    #endif
  }
  Timer timer = {
      /*TCCRnQ*/  { nullptr, nullptr, nullptr },
      /*OCRnQ*/   { nullptr, nullptr, nullptr },
      /*ICRn*/      nullptr,
                    0, 0
  };
  return timer;
}

void set_pwm_frequency(const pin_t pin, int f_desired) {
  Timer timer = get_pwm_timer(pin);
  if (timer.n == 0) return; // Don't proceed if protected timer or not recognised
  uint16_t size;
  if (timer.n == 2) size = 255; else size = 65535;

  uint16_t res = 255;   // resolution (TOP value)
  uint8_t j = 0;        // prescaler index
  uint8_t wgm = 1;      // waveform generation mode

  // Calculating the prescaler and resolution to use to achieve closest frequency
  if (f_desired != 0) {
    int f = (F_CPU) / (2 * 1024 * size) + 1; // Initialize frequency as lowest (non-zero) achievable
    uint16_t prescaler[] = { 0, 1, 8, /*TIMER2 ONLY*/32, 64, /*TIMER2 ONLY*/128, 256, 1024 };

    // loop over prescaler values
    LOOP_S_L_N(i, 1, 8) {
      uint16_t res_temp_fast = 255, res_temp_phase_correct = 255;
      if (timer.n == 2) {
        // No resolution calculation for TIMER2 unless enabled USE_OCR2A_AS_TOP
        #if ENABLED(USE_OCR2A_AS_TOP)
          const uint16_t rtf = (F_CPU) / (prescaler[i] * f_desired);
          res_temp_fast = rtf - 1;
          res_temp_phase_correct = rtf / 2;
        #endif
      }
      else {
        // Skip TIMER2 specific prescalers when not TIMER2
        if (i == 3 || i == 5) continue;
        const uint16_t rtf = (F_CPU) / (prescaler[i] * f_desired);
        res_temp_fast = rtf - 1;
        res_temp_phase_correct = rtf / 2;
      }

      LIMIT(res_temp_fast, 1u, size);
      LIMIT(res_temp_phase_correct, 1u, size);
      // Calculate frequencies of test prescaler and resolution values
      const int f_temp_fast = (F_CPU) / (prescaler[i] * (1 + res_temp_fast)),
                f_temp_phase_correct = (F_CPU) / (2 * prescaler[i] * res_temp_phase_correct),
                f_diff = ABS(f - f_desired),
                f_fast_diff = ABS(f_temp_fast - f_desired),
                f_phase_diff = ABS(f_temp_phase_correct - f_desired);

      // If FAST values are closest to desired f
      if (f_fast_diff < f_diff && f_fast_diff <= f_phase_diff) {
        // Remember this combination
        f = f_temp_fast;
        res = res_temp_fast;
        j = i;
        // Set the Wave Generation Mode to FAST PWM
        if (timer.n == 2) {
          wgm = (
            #if ENABLED(USE_OCR2A_AS_TOP)
              WGM2_FAST_PWM_OCR2A
            #else
              WGM2_FAST_PWM
            #endif
          );
        }
        else wgm = WGM_FAST_PWM_ICRn;
      }
      // If PHASE CORRECT values are closes to desired f
      else if (f_phase_diff < f_diff) {
        f = f_temp_phase_correct;
        res = res_temp_phase_correct;
        j = i;
        // Set the Wave Generation Mode to PWM PHASE CORRECT
        if (timer.n == 2) {
          wgm = (
            #if ENABLED(USE_OCR2A_AS_TOP)
              WGM2_PWM_PC_OCR2A
            #else
              WGM2_PWM_PC
            #endif
          );
        }
        else wgm = WGM_PWM_PC_ICRn;
      }
    }
  }
  _SET_WGMnQ(timer.TCCRnQ, wgm);
  _SET_CSn(timer.TCCRnQ, j);

  if (timer.n == 2) {
    #if ENABLED(USE_OCR2A_AS_TOP)
      _SET_OCRnQ(timer.OCRnQ, 0, res);  // Set OCR2A value (TOP) = res
    #endif
  }
  else
    _SET_ICRn(timer.ICRn, res);         // Set ICRn value (TOP) = res
}

void set_pwm_duty(const pin_t pin, const uint16_t v, const uint16_t v_size/*=255*/, const bool invert/*=false*/) {
  // If v is 0 or v_size (max), digitalWrite to LOW or HIGH.
  // Note that digitalWrite also disables pwm output for us (sets COM bit to 0)
  if (v == 0)
    digitalWrite(pin, invert);
  else if (v == v_size)
    digitalWrite(pin, !invert);
  else {
    Timer timer = get_pwm_timer(pin);
    if (timer.n == 0) return; // Don't proceed if protected timer or not recognised
    // Set compare output mode to CLEAR -> SET or SET -> CLEAR (if inverted)
    _SET_COMnQ(timer.TCCRnQ, (timer.q
        #ifdef TCCR2
          + (timer.q == 2) // COM20 is on bit 4 of TCCR2, thus requires q + 1 in the macro
        #endif
      ), COM_CLEAR_SET + invert
    );

    uint16_t top;
    if (timer.n == 2) { // if TIMER2
      top = (
        #if ENABLED(USE_OCR2A_AS_TOP)
          *timer.OCRnQ[0] // top = OCR2A
        #else
          255 // top = 0xFF (max)
        #endif
      );
    }
    else
      top = *timer.ICRn; // top = ICRn

    _SET_OCRnQ(timer.OCRnQ, timer.q, v * float(top) / float(v_size)); // Scale 8/16-bit v to top value
  }
}

#endif // NEEDS_HARDWARE_PWM
#endif // __AVR__