text: /* mbed Microcontroller Library
   * Copyright (c) 2006-2013 ARM Limited
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  #include "pwmout_api.h"
  
  #include "cmsis.h"
  #include "pinmap.h"
  #include "error.h"
  
  static const PinMap PinMap_PWM[] = {
      // LEDs
      {LED_RED  , PWM_3 , 4}, // PTC3, FTM0 CH2
      {LED_GREEN, PWM_5,  4}, // PTD4, FTM0 CH4
      {LED_BLUE , PWM_8 , 3}, // PTA2, FTM0 CH7
  
      // Arduino digital pinout
      {D3,  PWM_5 , 4}, // PTD4, FTM0 CH4
      {D5,  PWM_7 , 3}, // PTA1, FTM0 CH6
      {D6,  PWM_3 , 4}, // PTC3, FTM0 CH2
      {D9,  PWM_6 , 4}, // PTD5, FTM0 CH6
      {D10, PWM_2 , 4}, // PTC2, FTM0 CH1
  
      {PTA0,  PWM_6 , 3}, // PTA0, FTM0 CH5
      {PTA3,  PWM_1 , 3}, // PTA3, FTM0 CH0
      {PTA4,  PWM_2 , 3}, // PTA4, FTM0 CH1
      {PTA5,  PWM_3 , 3}, // PTA5, FTM0 CH2
      {PTA12, PWM_9 , 3}, // PTA12, FTM1 CH0
      {PTA13, PWM_10, 3}, // PTA13, FTM1 CH1
      {PTB0,  PWM_9 , 3}, // PTB0, FTM1 CH0
      {PTB1,  PWM_10, 3}, // PTB1, FTM1 CH1
      {PTC1,  PWM_1 , 4}, // PTC1, FTM0 CH0
      {PTD4,  PWM_4 , 4}, // PTD4, FTM0 CH3
      {PTD6,  PWM_7 , 4}, // PTD6, FTM0 CH6
      {PTD7,  PWM_8 , 4}, // PTD7, FTM0 CH7
  
      {NC , NC    , 0}
  };
  
  static float pwm_clock = 0;
  
  void pwmout_init(pwmout_t* obj, PinName pin) {
      // determine the channel
      PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
      if (pwm == (PWMName)NC)
          error("PwmOut pin mapping failed");
  
      uint32_t clkdiv = 0;
      float clkval = SystemCoreClock / 1000000.0f;
  
      while (clkval > 1) {
          clkdiv++;
          clkval /= 2.0;
          if (clkdiv == 7)
              break;
      }
  
      pwm_clock = clkval;
      unsigned int port = (unsigned int)pin >> PORT_SHIFT;
      unsigned int ftm_n = (pwm >> TPM_SHIFT);
      unsigned int ch_n = (pwm & 0xFF);
  
      SIM->SCGC5 |= 1 << (SIM_SCGC5_PORTA_SHIFT + port);
      SIM->SCGC6 |= 1 << (SIM_SCGC6_FTM0_SHIFT + ftm_n);
  
      FTM_Type *ftm = (FTM_Type *)(FTM0_BASE + 0x1000 * ftm_n);
      ftm->CONF |= FTM_CONF_BDMMODE(3);
      ftm->SC = FTM_SC_CLKS(1) | FTM_SC_PS(clkdiv); // (clock)MHz / clkdiv ~= (0.75)MHz
      ftm->CONTROLS[ch_n].CnSC = (FTM_CnSC_MSB_MASK | FTM_CnSC_ELSB_MASK); /* No Interrupts; High True pulses on Edge Aligned PWM */
  
      obj->CnV = &ftm->CONTROLS[ch_n].CnV;
      obj->MOD = &ftm->MOD;
      obj->CNT = &ftm->CNT;
  
      // default to 20ms: standard for servos, and fine for e.g. brightness control
      pwmout_period_ms(obj, 20);
      pwmout_write(obj, 0);
  
      // Wire pinout
      pinmap_pinout(pin, PinMap_PWM);
  }
  
  void pwmout_free(pwmout_t* obj) {}
  
  void pwmout_write(pwmout_t* obj, float value) {
      if (value < 0.0) {
          value = 0.0;
      } else if (value > 1.0) {
          value = 1.0;
      }
  
      *obj->CnV = (uint32_t)((float)(*obj->MOD) * value);
  }
  
  float pwmout_read(pwmout_t* obj) {
      float v = (float)(*obj->CnV) / (float)(*obj->MOD);
      return (v > 1.0) ? (1.0) : (v);
  }
  
  void pwmout_period(pwmout_t* obj, float seconds) {
      pwmout_period_us(obj, seconds * 1000000.0f);
  }
  
  void pwmout_period_ms(pwmout_t* obj, int ms) {
      pwmout_period_us(obj, ms * 1000);
  }
  
  // Set the PWM period, keeping the duty cycle the same.
  void pwmout_period_us(pwmout_t* obj, int us) {
      float dc = pwmout_read(obj);
      *obj->MOD = (uint32_t)(pwm_clock * (float)us);
      pwmout_write(obj, dc);
  }
  
  void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
      pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
  }
  
  void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
      pwmout_pulsewidth_us(obj, ms * 1000);
  }
  
  void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
      *obj->CnV = (uint32_t)(pwm_clock * (float)us);
  }
  