Lee Kai Xuan / mbed-os

mbed-os

Fork of mbed-os by erkin yucel

targets/TARGET_Freescale/TARGET_K20XX/pwmout_api.c@0:f269e3021894, 2016-10-23 (annotated)

Committer:
elessair
Date:
Sun Oct 23 15:10:02 2016 +0000
Revision:
0:f269e3021894
Initial commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
elessair 0:f269e3021894 1 /* mbed Microcontroller Library
elessair 0:f269e3021894 2 * Copyright (c) 2006-2015 ARM Limited
elessair 0:f269e3021894 3 *
elessair 0:f269e3021894 4 * Licensed under the Apache License, Version 2.0 (the "License");
elessair 0:f269e3021894 5 * you may not use this file except in compliance with the License.
elessair 0:f269e3021894 6 * You may obtain a copy of the License at
elessair 0:f269e3021894 7 *
elessair 0:f269e3021894 8 * http://www.apache.org/licenses/LICENSE-2.0
elessair 0:f269e3021894 9 *
elessair 0:f269e3021894 10 * Unless required by applicable law or agreed to in writing, software
elessair 0:f269e3021894 11 * distributed under the License is distributed on an "AS IS" BASIS,
elessair 0:f269e3021894 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
elessair 0:f269e3021894 13 * See the License for the specific language governing permissions and
elessair 0:f269e3021894 14 * limitations under the License.
elessair 0:f269e3021894 15 */
elessair 0:f269e3021894 16 #include "mbed_assert.h"
elessair 0:f269e3021894 17 #include "pwmout_api.h"
elessair 0:f269e3021894 18
elessair 0:f269e3021894 19 #include "cmsis.h"
elessair 0:f269e3021894 20 #include "pinmap.h"
elessair 0:f269e3021894 21 #include "PeripheralPins.h"
elessair 0:f269e3021894 22
elessair 0:f269e3021894 23 static float pwm_clock = 0;
elessair 0:f269e3021894 24
elessair 0:f269e3021894 25 void pwmout_init(pwmout_t* obj, PinName pin) {
elessair 0:f269e3021894 26 // determine the channel
elessair 0:f269e3021894 27 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
elessair 0:f269e3021894 28 MBED_ASSERT(pwm != (PWMName)NC);
elessair 0:f269e3021894 29
elessair 0:f269e3021894 30 uint32_t clkdiv = 0;
elessair 0:f269e3021894 31 float clkval = SystemCoreClock / 1000000.0f;
elessair 0:f269e3021894 32
elessair 0:f269e3021894 33 while (clkval > 1) {
elessair 0:f269e3021894 34 clkdiv++;
elessair 0:f269e3021894 35 clkval /= 2.0;
elessair 0:f269e3021894 36 if (clkdiv == 7)
elessair 0:f269e3021894 37 break;
elessair 0:f269e3021894 38 }
elessair 0:f269e3021894 39
elessair 0:f269e3021894 40 pwm_clock = clkval;
elessair 0:f269e3021894 41 unsigned int ftm_n = (pwm >> TPM_SHIFT);
elessair 0:f269e3021894 42 unsigned int ch_n = (pwm & 0xFF);
elessair 0:f269e3021894 43
elessair 0:f269e3021894 44 SIM->SCGC6 |= 1 << (SIM_SCGC6_FTM0_SHIFT + ftm_n);
elessair 0:f269e3021894 45
elessair 0:f269e3021894 46 FTM_Type *ftm = (FTM_Type *)(FTM0_BASE + 0x1000 * ftm_n);
elessair 0:f269e3021894 47 ftm->CONF |= FTM_CONF_BDMMODE(3);
elessair 0:f269e3021894 48 ftm->SC = FTM_SC_CLKS(1) | FTM_SC_PS(clkdiv); // (clock)MHz / clkdiv ~= (0.75)MHz
elessair 0:f269e3021894 49 ftm->CONTROLS[ch_n].CnSC = (FTM_CnSC_MSB_MASK | FTM_CnSC_ELSB_MASK); /* No Interrupts; High True pulses on Edge Aligned PWM */
elessair 0:f269e3021894 50 ftm->MODE = FTM_MODE_FTMEN_MASK;
elessair 0:f269e3021894 51 ftm->SYNC = FTM_SYNC_CNTMIN_MASK;
elessair 0:f269e3021894 52 ftm->SYNCONF = FTM_SYNCONF_SYNCMODE_MASK | FTM_SYNCONF_SWSOC_MASK | FTM_SYNCONF_SWWRBUF_MASK;
elessair 0:f269e3021894 53
elessair 0:f269e3021894 54 //Without SYNCEN set CnV does not seem to update
elessair 0:f269e3021894 55 ftm->COMBINE = FTM_COMBINE_SYNCEN0_MASK | FTM_COMBINE_SYNCEN1_MASK | FTM_COMBINE_SYNCEN2_MASK | FTM_COMBINE_SYNCEN3_MASK;
elessair 0:f269e3021894 56
elessair 0:f269e3021894 57 obj->CnV = &ftm->CONTROLS[ch_n].CnV;
elessair 0:f269e3021894 58 obj->MOD = &ftm->MOD;
elessair 0:f269e3021894 59 obj->SYNC = &ftm->SYNC;
elessair 0:f269e3021894 60
elessair 0:f269e3021894 61 // default to 20ms: standard for servos, and fine for e.g. brightness control
elessair 0:f269e3021894 62 pwmout_period_ms(obj, 20);
elessair 0:f269e3021894 63 pwmout_write(obj, 0.0);
elessair 0:f269e3021894 64
elessair 0:f269e3021894 65 // Wire pinout
elessair 0:f269e3021894 66 pinmap_pinout(pin, PinMap_PWM);
elessair 0:f269e3021894 67 }
elessair 0:f269e3021894 68
elessair 0:f269e3021894 69 void pwmout_free(pwmout_t* obj) {}
elessair 0:f269e3021894 70
elessair 0:f269e3021894 71 void pwmout_write(pwmout_t* obj, float value) {
elessair 0:f269e3021894 72 if (value < 0.0) {
elessair 0:f269e3021894 73 value = 0.0;
elessair 0:f269e3021894 74 } else if (value > 1.0) {
elessair 0:f269e3021894 75 value = 1.0;
elessair 0:f269e3021894 76 }
elessair 0:f269e3021894 77
elessair 0:f269e3021894 78 while(*obj->SYNC & FTM_SYNC_SWSYNC_MASK);
elessair 0:f269e3021894 79 *obj->CnV = (uint32_t)((float)(*obj->MOD + 1) * value);
elessair 0:f269e3021894 80 *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
elessair 0:f269e3021894 81 }
elessair 0:f269e3021894 82
elessair 0:f269e3021894 83 float pwmout_read(pwmout_t* obj) {
elessair 0:f269e3021894 84 while(*obj->SYNC & FTM_SYNC_SWSYNC_MASK);
elessair 0:f269e3021894 85 float v = (float)(*obj->CnV) / (float)(*obj->MOD + 1);
elessair 0:f269e3021894 86 return (v > 1.0) ? (1.0) : (v);
elessair 0:f269e3021894 87 }
elessair 0:f269e3021894 88
elessair 0:f269e3021894 89 void pwmout_period(pwmout_t* obj, float seconds) {
elessair 0:f269e3021894 90 pwmout_period_us(obj, seconds * 1000000.0f);
elessair 0:f269e3021894 91 }
elessair 0:f269e3021894 92
elessair 0:f269e3021894 93 void pwmout_period_ms(pwmout_t* obj, int ms) {
elessair 0:f269e3021894 94 pwmout_period_us(obj, ms * 1000);
elessair 0:f269e3021894 95 }
elessair 0:f269e3021894 96
elessair 0:f269e3021894 97 // Set the PWM period, keeping the duty cycle the same.
elessair 0:f269e3021894 98 void pwmout_period_us(pwmout_t* obj, int us) {
elessair 0:f269e3021894 99 float dc = pwmout_read(obj);
elessair 0:f269e3021894 100 *obj->MOD = (uint32_t)(pwm_clock * (float)us) - 1;
elessair 0:f269e3021894 101 *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
elessair 0:f269e3021894 102 pwmout_write(obj, dc);
elessair 0:f269e3021894 103 }
elessair 0:f269e3021894 104
elessair 0:f269e3021894 105 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
elessair 0:f269e3021894 106 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
elessair 0:f269e3021894 107 }
elessair 0:f269e3021894 108
elessair 0:f269e3021894 109 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
elessair 0:f269e3021894 110 pwmout_pulsewidth_us(obj, ms * 1000);
elessair 0:f269e3021894 111 }
elessair 0:f269e3021894 112
elessair 0:f269e3021894 113 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
elessair 0:f269e3021894 114 *obj->CnV = (uint32_t)(pwm_clock * (float)us);
elessair 0:f269e3021894 115 *obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
elessair 0:f269e3021894 116 }