EL4121 Embedded System / mbed-os

mbed-os

Dependents:   cobaLCDJoyMotor_Thread odometry_omni_3roda_v3 odometry_omni_3roda_v1 odometry_omni_3roda_v2 ... more

targets/TARGET_NXP/TARGET_LPC11UXX/pwmout_api.c@0:b74591d5ab33, 2017-12-11 (annotated)

Committer:
be_bryan
Date:
Mon Dec 11 17:54:04 2017 +0000
Revision:
0:b74591d5ab33
motor ++

Who changed what in which revision?

UserRevisionLine numberNew contents of line
be_bryan 0:b74591d5ab33 1 /* mbed Microcontroller Library
be_bryan 0:b74591d5ab33 2 * Copyright (c) 2006-2013 ARM Limited
be_bryan 0:b74591d5ab33 3 *
be_bryan 0:b74591d5ab33 4 * Licensed under the Apache License, Version 2.0 (the "License");
be_bryan 0:b74591d5ab33 5 * you may not use this file except in compliance with the License.
be_bryan 0:b74591d5ab33 6 * You may obtain a copy of the License at
be_bryan 0:b74591d5ab33 7 *
be_bryan 0:b74591d5ab33 8 * http://www.apache.org/licenses/LICENSE-2.0
be_bryan 0:b74591d5ab33 9 *
be_bryan 0:b74591d5ab33 10 * Unless required by applicable law or agreed to in writing, software
be_bryan 0:b74591d5ab33 11 * distributed under the License is distributed on an "AS IS" BASIS,
be_bryan 0:b74591d5ab33 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
be_bryan 0:b74591d5ab33 13 * See the License for the specific language governing permissions and
be_bryan 0:b74591d5ab33 14 * limitations under the License.
be_bryan 0:b74591d5ab33 15 */
be_bryan 0:b74591d5ab33 16 #include "mbed_assert.h"
be_bryan 0:b74591d5ab33 17 #include "pwmout_api.h"
be_bryan 0:b74591d5ab33 18 #include "cmsis.h"
be_bryan 0:b74591d5ab33 19 #include "pinmap.h"
be_bryan 0:b74591d5ab33 20 #include "PeripheralPins.h" // For the Peripheral to Pin Definitions found in the individual Target's Platform
be_bryan 0:b74591d5ab33 21
be_bryan 0:b74591d5ab33 22 #define TCR_CNT_EN 0x00000001
be_bryan 0:b74591d5ab33 23 #define TCR_RESET 0x00000002
be_bryan 0:b74591d5ab33 24
be_bryan 0:b74591d5ab33 25 typedef struct {
be_bryan 0:b74591d5ab33 26 uint8_t timer;
be_bryan 0:b74591d5ab33 27 uint8_t mr;
be_bryan 0:b74591d5ab33 28 } timer_mr;
be_bryan 0:b74591d5ab33 29
be_bryan 0:b74591d5ab33 30 static timer_mr pwm_timer_map[11] = {
be_bryan 0:b74591d5ab33 31 {0, 0}, {0, 1}, {0, 2},
be_bryan 0:b74591d5ab33 32 {1, 0}, {1, 1},
be_bryan 0:b74591d5ab33 33 {2, 0}, {2, 1}, {2, 2},
be_bryan 0:b74591d5ab33 34 {3, 0}, {3, 1}, {3, 2},
be_bryan 0:b74591d5ab33 35 };
be_bryan 0:b74591d5ab33 36
be_bryan 0:b74591d5ab33 37 static LPC_CTxxBx_Type *Timers[4] = {
be_bryan 0:b74591d5ab33 38 LPC_CT16B0, LPC_CT16B1,
be_bryan 0:b74591d5ab33 39 LPC_CT32B0, LPC_CT32B1
be_bryan 0:b74591d5ab33 40 };
be_bryan 0:b74591d5ab33 41
be_bryan 0:b74591d5ab33 42 void pwmout_init(pwmout_t* obj, PinName pin) {
be_bryan 0:b74591d5ab33 43 // determine the channel
be_bryan 0:b74591d5ab33 44 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
be_bryan 0:b74591d5ab33 45 MBED_ASSERT(pwm != (PWMName)NC);
be_bryan 0:b74591d5ab33 46
be_bryan 0:b74591d5ab33 47 obj->pwm = pwm;
be_bryan 0:b74591d5ab33 48
be_bryan 0:b74591d5ab33 49 // Timer registers
be_bryan 0:b74591d5ab33 50 timer_mr tid = pwm_timer_map[pwm];
be_bryan 0:b74591d5ab33 51 LPC_CTxxBx_Type *timer = Timers[tid.timer];
be_bryan 0:b74591d5ab33 52
be_bryan 0:b74591d5ab33 53 // Disable timer
be_bryan 0:b74591d5ab33 54 timer->TCR = 0;
be_bryan 0:b74591d5ab33 55
be_bryan 0:b74591d5ab33 56 // Power the correspondent timer
be_bryan 0:b74591d5ab33 57 LPC_SYSCON->SYSAHBCLKCTRL |= 1 << (tid.timer + 7);
be_bryan 0:b74591d5ab33 58
be_bryan 0:b74591d5ab33 59 /* Enable PWM function */
be_bryan 0:b74591d5ab33 60 timer->PWMC = (1 << 3)|(1 << 2)|(1 << 1)|(1 << 0);
be_bryan 0:b74591d5ab33 61
be_bryan 0:b74591d5ab33 62 /* Reset Functionality on MR3 controlling the PWM period */
be_bryan 0:b74591d5ab33 63 timer->MCR = 1 << 10;
be_bryan 0:b74591d5ab33 64
be_bryan 0:b74591d5ab33 65 // default to 20ms: standard for servos, and fine for e.g. brightness control
be_bryan 0:b74591d5ab33 66 pwmout_period_ms(obj, 20);
be_bryan 0:b74591d5ab33 67 pwmout_write (obj, 0);
be_bryan 0:b74591d5ab33 68
be_bryan 0:b74591d5ab33 69 // Wire pinout
be_bryan 0:b74591d5ab33 70 pinmap_pinout(pin, PinMap_PWM);
be_bryan 0:b74591d5ab33 71 }
be_bryan 0:b74591d5ab33 72
be_bryan 0:b74591d5ab33 73 void pwmout_free(pwmout_t* obj) {
be_bryan 0:b74591d5ab33 74 // [TODO]
be_bryan 0:b74591d5ab33 75 }
be_bryan 0:b74591d5ab33 76
be_bryan 0:b74591d5ab33 77 void pwmout_write(pwmout_t* obj, float value) {
be_bryan 0:b74591d5ab33 78 if (value < 0.0f) {
be_bryan 0:b74591d5ab33 79 value = 0.0;
be_bryan 0:b74591d5ab33 80 } else if (value > 1.0f) {
be_bryan 0:b74591d5ab33 81 value = 1.0;
be_bryan 0:b74591d5ab33 82 }
be_bryan 0:b74591d5ab33 83
be_bryan 0:b74591d5ab33 84 timer_mr tid = pwm_timer_map[obj->pwm];
be_bryan 0:b74591d5ab33 85 LPC_CTxxBx_Type *timer = Timers[tid.timer];
be_bryan 0:b74591d5ab33 86 uint32_t t_off = timer->MR3 - (uint32_t)((float)(timer->MR3) * value);
be_bryan 0:b74591d5ab33 87
be_bryan 0:b74591d5ab33 88 timer->MR[tid.mr] = t_off;
be_bryan 0:b74591d5ab33 89 }
be_bryan 0:b74591d5ab33 90
be_bryan 0:b74591d5ab33 91 float pwmout_read(pwmout_t* obj) {
be_bryan 0:b74591d5ab33 92 timer_mr tid = pwm_timer_map[obj->pwm];
be_bryan 0:b74591d5ab33 93 LPC_CTxxBx_Type *timer = Timers[tid.timer];
be_bryan 0:b74591d5ab33 94
be_bryan 0:b74591d5ab33 95 float v = (float)(timer->MR3 - timer->MR[tid.mr]) / (float)(timer->MR3);
be_bryan 0:b74591d5ab33 96 return (v > 1.0f) ? (1.0f) : (v);
be_bryan 0:b74591d5ab33 97 }
be_bryan 0:b74591d5ab33 98
be_bryan 0:b74591d5ab33 99 void pwmout_period(pwmout_t* obj, float seconds) {
be_bryan 0:b74591d5ab33 100 pwmout_period_us(obj, seconds * 1000000.0f);
be_bryan 0:b74591d5ab33 101 }
be_bryan 0:b74591d5ab33 102
be_bryan 0:b74591d5ab33 103 void pwmout_period_ms(pwmout_t* obj, int ms) {
be_bryan 0:b74591d5ab33 104 pwmout_period_us(obj, ms * 1000);
be_bryan 0:b74591d5ab33 105 }
be_bryan 0:b74591d5ab33 106
be_bryan 0:b74591d5ab33 107 // Set the PWM period, keeping the duty cycle the same.
be_bryan 0:b74591d5ab33 108 void pwmout_period_us(pwmout_t* obj, int us) {
be_bryan 0:b74591d5ab33 109 int i = 0;
be_bryan 0:b74591d5ab33 110 uint32_t period_ticks = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000);
be_bryan 0:b74591d5ab33 111
be_bryan 0:b74591d5ab33 112 timer_mr tid = pwm_timer_map[obj->pwm];
be_bryan 0:b74591d5ab33 113 LPC_CTxxBx_Type *timer = Timers[tid.timer];
be_bryan 0:b74591d5ab33 114 uint32_t old_period_ticks = timer->MR3;
be_bryan 0:b74591d5ab33 115
be_bryan 0:b74591d5ab33 116 // for 16bit timer, set prescaler to avoid overflow
be_bryan 0:b74591d5ab33 117 if (timer == LPC_CT16B0 || timer == LPC_CT16B1) {
be_bryan 0:b74591d5ab33 118 uint16_t high_period_ticks = period_ticks >> 16;
be_bryan 0:b74591d5ab33 119 timer->PR = high_period_ticks;
be_bryan 0:b74591d5ab33 120 period_ticks /= (high_period_ticks + 1);
be_bryan 0:b74591d5ab33 121 }
be_bryan 0:b74591d5ab33 122
be_bryan 0:b74591d5ab33 123 timer->TCR = TCR_RESET;
be_bryan 0:b74591d5ab33 124 timer->MR3 = period_ticks;
be_bryan 0:b74591d5ab33 125
be_bryan 0:b74591d5ab33 126 // Scale the pulse width to preserve the duty ratio
be_bryan 0:b74591d5ab33 127 if (old_period_ticks > 0) {
be_bryan 0:b74591d5ab33 128 for (i=0; i<3; i++) {
be_bryan 0:b74591d5ab33 129 uint32_t t_off = period_ticks - (uint32_t)(((uint64_t)timer->MR[i] * (uint64_t)period_ticks) / (uint64_t)old_period_ticks);
be_bryan 0:b74591d5ab33 130 timer->MR[i] = t_off;
be_bryan 0:b74591d5ab33 131 }
be_bryan 0:b74591d5ab33 132 }
be_bryan 0:b74591d5ab33 133 timer->TCR = TCR_CNT_EN;
be_bryan 0:b74591d5ab33 134 }
be_bryan 0:b74591d5ab33 135
be_bryan 0:b74591d5ab33 136 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
be_bryan 0:b74591d5ab33 137 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
be_bryan 0:b74591d5ab33 138 }
be_bryan 0:b74591d5ab33 139
be_bryan 0:b74591d5ab33 140 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
be_bryan 0:b74591d5ab33 141 pwmout_pulsewidth_us(obj, ms * 1000);
be_bryan 0:b74591d5ab33 142 }
be_bryan 0:b74591d5ab33 143
be_bryan 0:b74591d5ab33 144 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
be_bryan 0:b74591d5ab33 145 timer_mr tid = pwm_timer_map[obj->pwm];
be_bryan 0:b74591d5ab33 146 LPC_CTxxBx_Type *timer = Timers[tid.timer];
be_bryan 0:b74591d5ab33 147 uint32_t t_on = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000 / (timer->PR + 1));
be_bryan 0:b74591d5ab33 148
be_bryan 0:b74591d5ab33 149 timer->TCR = TCR_RESET;
be_bryan 0:b74591d5ab33 150 if (t_on > timer->MR3) {
be_bryan 0:b74591d5ab33 151 pwmout_period_us(obj, us);
be_bryan 0:b74591d5ab33 152 t_on = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000 / (timer->PR + 1));
be_bryan 0:b74591d5ab33 153 }
be_bryan 0:b74591d5ab33 154 uint32_t t_off = timer->MR3 - t_on;
be_bryan 0:b74591d5ab33 155 timer->MR[tid.mr] = t_off;
be_bryan 0:b74591d5ab33 156 timer->TCR = TCR_CNT_EN;
be_bryan 0:b74591d5ab33 157 }