mirror of https://github.com/ARMmbed/mbed-os.git
120 lines
3.8 KiB
C
120 lines
3.8 KiB
C
/* mbed Microcontroller Library
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* Copyright (c) 2006-2015 ARM Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "mbed_assert.h"
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#include "pwmout_api.h"
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#include "cmsis.h"
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#include "pinmap.h"
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#include "PeripheralPins.h"
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static float pwm_clock = 0;
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void pwmout_init(pwmout_t* obj, PinName pin) {
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// determine the channel
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PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
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MBED_ASSERT(pwm != (PWMName)NC);
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uint32_t MGCOUTClock = SystemCoreClock * (1u + ((SIM->CLKDIV1 & SIM_CLKDIV1_OUTDIV1_MASK) >> SIM_CLKDIV1_OUTDIV1_SHIFT));
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uint32_t BusClock = MGCOUTClock / (1u + ((SIM->CLKDIV1 & SIM_CLKDIV1_OUTDIV2_MASK) >> SIM_CLKDIV1_OUTDIV2_SHIFT));
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uint32_t clkdiv = 0;
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float clkval = BusClock / 1000000.0f;
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while (clkval > 1) {
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clkdiv++;
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clkval /= 2.0;
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if (clkdiv == 7)
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break;
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}
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pwm_clock = clkval;
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unsigned int ftm_n = (pwm >> TPM_SHIFT);
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unsigned int ch_n = (pwm & 0xFF);
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SIM->SCGC6 |= 1 << (SIM_SCGC6_FTM0_SHIFT + ftm_n);
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FTM_Type *ftm = (FTM_Type *)(FTM0_BASE + 0x1000 * ftm_n);
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ftm->CONF |= FTM_CONF_BDMMODE(3);
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ftm->SC = FTM_SC_CLKS(1) | FTM_SC_PS(clkdiv); // (clock)MHz / clkdiv ~= (0.75)MHz
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ftm->CONTROLS[ch_n].CnSC = (FTM_CnSC_MSB_MASK | FTM_CnSC_ELSB_MASK); /* No Interrupts; High True pulses on Edge Aligned PWM */
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ftm->MODE = FTM_MODE_FTMEN_MASK;
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ftm->SYNC = FTM_SYNC_CNTMIN_MASK;
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ftm->SYNCONF = FTM_SYNCONF_SYNCMODE_MASK | FTM_SYNCONF_SWSOC_MASK | FTM_SYNCONF_SWWRBUF_MASK;
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//Without SYNCEN set CnV does not seem to update
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ftm->COMBINE = FTM_COMBINE_SYNCEN0_MASK | FTM_COMBINE_SYNCEN1_MASK | FTM_COMBINE_SYNCEN2_MASK | FTM_COMBINE_SYNCEN3_MASK;
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obj->CnV = &ftm->CONTROLS[ch_n].CnV;
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obj->MOD = &ftm->MOD;
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obj->SYNC = &ftm->SYNC;
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// default to 20ms: standard for servos, and fine for e.g. brightness control
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pwmout_period_ms(obj, 20);
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pwmout_write(obj, 0.0);
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// Wire pinout
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pinmap_pinout(pin, PinMap_PWM);
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}
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void pwmout_free(pwmout_t* obj) {}
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void pwmout_write(pwmout_t* obj, float value) {
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if (value < 0.0) {
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value = 0.0;
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} else if (value > 1.0) {
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value = 1.0;
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}
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while(*obj->SYNC & FTM_SYNC_SWSYNC_MASK);
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*obj->CnV = (uint32_t)((float)(*obj->MOD + 1) * value);
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*obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
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}
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float pwmout_read(pwmout_t* obj) {
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while(*obj->SYNC & FTM_SYNC_SWSYNC_MASK);
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float v = (float)(*obj->CnV) / (float)(*obj->MOD + 1);
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return (v > 1.0) ? (1.0) : (v);
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}
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void pwmout_period(pwmout_t* obj, float seconds) {
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pwmout_period_us(obj, seconds * 1000000.0f);
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}
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void pwmout_period_ms(pwmout_t* obj, int ms) {
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pwmout_period_us(obj, ms * 1000);
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}
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// Set the PWM period, keeping the duty cycle the same.
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void pwmout_period_us(pwmout_t* obj, int us) {
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float dc = pwmout_read(obj);
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*obj->MOD = (uint32_t)(pwm_clock * (float)us) - 1;
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*obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
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pwmout_write(obj, dc);
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}
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void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
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pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
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}
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void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
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pwmout_pulsewidth_us(obj, ms * 1000);
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}
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void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
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*obj->CnV = (uint32_t)(pwm_clock * (float)us);
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*obj->SYNC |= FTM_SYNC_SWSYNC_MASK;
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}
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