text: /**
   * 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/>.
   *
   */
  
  
  /**
   * Description: HAL for Teensy32 (MK20DX256)
   */
  
  #ifdef __MK20DX256__
  
  #include "HAL.h"
  #include "../shared/Delay.h"
  
  #include <Wire.h>
  
  uint16_t HAL_adc_result;
  
  static const uint8_t pin2sc1a[] = {
      5, 14, 8, 9, 13, 12, 6, 7, 15, 4, 0, 19, 3, 31, // 0-13, we treat them as A0-A13
      5, 14, 8, 9, 13, 12, 6, 7, 15, 4, // 14-23 (A0-A9)
      31, 31, 31, 31, 31, 31, 31, 31, 31, 31, // 24-33
      0+64, 19+64, 3+64, 31+64, // 34-37 (A10-A13)
      26, 22, 23, 27, 29, 30 // 38-43: temp. sensor, VREF_OUT, A14, bandgap, VREFH, VREFL. A14 isn't connected to anything in Teensy 3.0.
  };
  
  /*
    // disable interrupts
    void cli() { noInterrupts(); }
  
    // enable interrupts
    void sei() { interrupts(); }
  */
  
  void HAL_adc_init() {
    analog_init();
    while (ADC0_SC3 & ADC_SC3_CAL) {}; // Wait for calibration to finish
    NVIC_ENABLE_IRQ(IRQ_FTM1);
  }
  
  void HAL_clear_reset_source() { }
  
  uint8_t HAL_get_reset_source() {
    switch (RCM_SRS0) {
      case 128: return RST_POWER_ON; break;
      case 64: return RST_EXTERNAL; break;
      case 32: return RST_WATCHDOG; break;
      // case 8: return RST_LOSS_OF_LOCK; break;
      // case 4: return RST_LOSS_OF_CLOCK; break;
      // case 2: return RST_LOW_VOLTAGE; break;
    }
    return 0;
  }
  
  extern "C" {
    extern char __bss_end;
    extern char __heap_start;
    extern void* __brkval;
  
    int freeMemory() {
      int free_memory;
      if ((int)__brkval == 0)
        free_memory = ((int)&free_memory) - ((int)&__bss_end);
      else
        free_memory = ((int)&free_memory) - ((int)__brkval);
      return free_memory;
    }
  }
  
  void HAL_adc_start_conversion(const uint8_t adc_pin) { ADC0_SC1A = pin2sc1a[adc_pin]; }
  
  uint16_t HAL_adc_get_result() { return ADC0_RA; }
  
  #endif // __MK20DX256__
  