tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_Freescale/TARGET_K20XX/pwmout_api.c

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2015 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #include "mbed_assert.h"
  17 #include "pwmout_api.h"
  18
  19 #include "cmsis.h"
  20 #include "pinmap.h"
  21 #include "PeripheralPins.h"
  22
  23 static float pwm_clock = 0;
  24
  25 void pwmout_init(pwmout_t* obj, PinName pin) {
  26     // determine the channel
  27     PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
  28     MBED_ASSERT(pwm != (PWMName)NC);
  29
  30     uint32_t clkdiv = 0;
  31     float clkval = SystemCoreClock / 1000000.0f;
  32
  33     while (clkval > 1) {
  34         clkdiv++;
  35         clkval /= 2.0;
  36         if (clkdiv == 7)
  37             break;
  38     }
  39
  40     pwm_clock = clkval;
  41     unsigned int ftm_n = (pwm >> TPM_SHIFT);
  42     unsigned int ch_n = (pwm & 0xFF);
  43
  44     SIM->SCGC6 |= 1 << (SIM_SCGC6_FTM0_SHIFT + ftm_n);
  45
  46     FTM_Type *ftm = (FTM_Type *)(FTM0_BASE + 0x1000 * ftm_n);
  47     ftm->CONF |= FTM_CONF_BDMMODE(3);
  48     ftm->SC = FTM_SC_CLKS(1) | FTM_SC_PS(clkdiv); // (clock)MHz / clkdiv ~= (0.75)MHz
  49     ftm->CONTROLS[ch_n].CnSC = (FTM_CnSC_MSB_MASK | FTM_CnSC_ELSB_MASK); /* No Interrupts; High True pulses on Edge Aligned PWM */
  50     ftm->MODE = FTM_MODE_FTMEN_MASK;
  51     ftm->SYNC = FTM_SYNC_CNTMIN_MASK;
  52     ftm->SYNCONF = FTM_SYNCONF_SYNCMODE_MASK | FTM_SYNCONF_SWSOC_MASK | FTM_SYNCONF_SWWRBUF_MASK;
  53
  54     //Without SYNCEN set CnV does not seem to update
  55     ftm->COMBINE = FTM_COMBINE_SYNCEN0_MASK | FTM_COMBINE_SYNCEN1_MASK | FTM_COMBINE_SYNCEN2_MASK | FTM_COMBINE_SYNCEN3_MASK;
  56
  57     obj->CnV = &ftm->CONTROLS[ch_n].CnV;
  58     obj->MOD = &ftm->MOD;
  59     obj->SYNC = &ftm->SYNC;
  60
  61     // default to 20ms: standard for servos, and fine for e.g. brightness control
  62     pwmout_period_ms(obj, 20);
  63     pwmout_write(obj, 0.0);
  64
  65     // Wire pinout
  66     pinmap_pinout(pin, PinMap_PWM);
  67 }
  68
  69 void pwmout_free(pwmout_t* obj) {}
  70
  71 void pwmout_write(pwmout_t* obj, float value) {
  72     if (value < 0.0) {
  73         value = 0.0;
  74     } else if (value > 1.0) {
  75         value = 1.0;
  76     }
  77
  78     while(*obj->SYNC & FTM_SYNC_SWSYNC_MASK);
  79     *obj->CnV = (uint32_t)((float)(*obj->MOD + 1) * value);
  80     *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
  81 }
  82
  83 float pwmout_read(pwmout_t* obj) {
  84     while(*obj->SYNC & FTM_SYNC_SWSYNC_MASK);
  85     float v = (float)(*obj->CnV) / (float)(*obj->MOD + 1);
  86     return (v > 1.0) ? (1.0) : (v);
  87 }
  88
  89 void pwmout_period(pwmout_t* obj, float seconds) {
  90     pwmout_period_us(obj, seconds * 1000000.0f);
  91 }
  92
  93 void pwmout_period_ms(pwmout_t* obj, int ms) {
  94     pwmout_period_us(obj, ms * 1000);
  95 }
  96
  97 // Set the PWM period, keeping the duty cycle the same.
  98 void pwmout_period_us(pwmout_t* obj, int us) {
  99     float dc = pwmout_read(obj);
 100     *obj->MOD = (uint32_t)(pwm_clock * (float)us) - 1;
 101     *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
 102     pwmout_write(obj, dc);
 103 }
 104
 105 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
 106     pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
 107 }
 108
 109 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
 110     pwmout_pulsewidth_us(obj, ms * 1000);
 111 }
 112
 113 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
 114     *obj->CnV = (uint32_t)(pwm_clock * (float)us);
 115     *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
 116 }