1 /* mbed Microcontroller Library
2 * Copyright (c) 2006-2015 ARM Limited
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
16 #include "mbed_assert.h"
17 #include "pwmout_api.h"
21 #include "PeripheralPins.h"
23 static float pwm_clock = 0;
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);
31 float clkval = SystemCoreClock / 1000000.0f;
41 unsigned int ftm_n = (pwm >> TPM_SHIFT);
42 unsigned int ch_n = (pwm & 0xFF);
44 SIM->SCGC6 |= 1 << (SIM_SCGC6_FTM0_SHIFT + ftm_n);
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;
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;
57 obj->CnV = &ftm->CONTROLS[ch_n].CnV;
59 obj->SYNC = &ftm->SYNC;
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);
66 pinmap_pinout(pin, PinMap_PWM);
69 void pwmout_free(pwmout_t* obj) {}
71 void pwmout_write(pwmout_t* obj, float value) {
74 } else if (value > 1.0) {
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;
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);
89 void pwmout_period(pwmout_t* obj, float seconds) {
90 pwmout_period_us(obj, seconds * 1000000.0f);
93 void pwmout_period_ms(pwmout_t* obj, int ms) {
94 pwmout_period_us(obj, ms * 1000);
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);
105 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
106 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
109 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
110 pwmout_pulsewidth_us(obj, ms * 1000);
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;