mbed official / mbed-dev

mbed library sources. Supersedes mbed-src.

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targets/hal/TARGET_NXP/TARGET_LPC11XX_11CXX/pwmout_api.c@0:9b334a45a8ff, 2015-10-01 (annotated)

Committer:
bogdanm
Date:
Thu Oct 01 15:25:22 2015 +0300
Revision:
0:9b334a45a8ff
Child:
144:ef7eb2e8f9f7
Initial commit on mbed-dev



Replaces mbed-src (now inactive)

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bogdanm 0:9b334a45a8ff 1 /* mbed Microcontroller Library
bogdanm 0:9b334a45a8ff 2 * Copyright (c) 2006-2013 ARM Limited
bogdanm 0:9b334a45a8ff 3 *
bogdanm 0:9b334a45a8ff 4 * Licensed under the Apache License, Version 2.0 (the "License");
bogdanm 0:9b334a45a8ff 5 * you may not use this file except in compliance with the License.
bogdanm 0:9b334a45a8ff 6 * You may obtain a copy of the License at
bogdanm 0:9b334a45a8ff 7 *
bogdanm 0:9b334a45a8ff 8 * http://www.apache.org/licenses/LICENSE-2.0
bogdanm 0:9b334a45a8ff 9 *
bogdanm 0:9b334a45a8ff 10 * Unless required by applicable law or agreed to in writing, software
bogdanm 0:9b334a45a8ff 11 * distributed under the License is distributed on an "AS IS" BASIS,
bogdanm 0:9b334a45a8ff 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
bogdanm 0:9b334a45a8ff 13 * See the License for the specific language governing permissions and
bogdanm 0:9b334a45a8ff 14 * limitations under the License.
bogdanm 0:9b334a45a8ff 15 */
bogdanm 0:9b334a45a8ff 16 #include "mbed_assert.h"
bogdanm 0:9b334a45a8ff 17 #include "pwmout_api.h"
bogdanm 0:9b334a45a8ff 18 #include "cmsis.h"
bogdanm 0:9b334a45a8ff 19 #include "pinmap.h"
bogdanm 0:9b334a45a8ff 20
bogdanm 0:9b334a45a8ff 21 #define TCR_CNT_EN 0x00000001
bogdanm 0:9b334a45a8ff 22 #define TCR_RESET 0x00000002
bogdanm 0:9b334a45a8ff 23
bogdanm 0:9b334a45a8ff 24 /* To have a PWM where we can change both the period and the duty cycle,
bogdanm 0:9b334a45a8ff 25 * we need an entire timer. With the following conventions:
bogdanm 0:9b334a45a8ff 26 * * MR3 is used for the PWM period
bogdanm 0:9b334a45a8ff 27 * * MR0, MR1, MR2 are used for the duty cycle
bogdanm 0:9b334a45a8ff 28 */
bogdanm 0:9b334a45a8ff 29 static const PinMap PinMap_PWM[] = {
bogdanm 0:9b334a45a8ff 30 /* CT16B0 */
bogdanm 0:9b334a45a8ff 31 {P0_8 , PWM_1, 0x02}, /* MR0 */
bogdanm 0:9b334a45a8ff 32 {P0_9 , PWM_2, 0x02}, /* MR1 */
bogdanm 0:9b334a45a8ff 33
bogdanm 0:9b334a45a8ff 34 /* CT16B1 */
bogdanm 0:9b334a45a8ff 35 {P1_9 , PWM_3, 0x01}, /* MR0 */
bogdanm 0:9b334a45a8ff 36 {P1_10, PWM_4, 0x02}, /* MR1 */
bogdanm 0:9b334a45a8ff 37
bogdanm 0:9b334a45a8ff 38 /* CT32B0 */
bogdanm 0:9b334a45a8ff 39 {P0_1 , PWM_5, 0x02}, /* MR2 */
bogdanm 0:9b334a45a8ff 40
bogdanm 0:9b334a45a8ff 41 {NC , NC ,0x00}
bogdanm 0:9b334a45a8ff 42 };
bogdanm 0:9b334a45a8ff 43
bogdanm 0:9b334a45a8ff 44 typedef struct {
bogdanm 0:9b334a45a8ff 45 uint8_t timer;
bogdanm 0:9b334a45a8ff 46 uint8_t mr;
bogdanm 0:9b334a45a8ff 47 } timer_mr;
bogdanm 0:9b334a45a8ff 48
bogdanm 0:9b334a45a8ff 49 static timer_mr pwm_timer_map[5] = {
bogdanm 0:9b334a45a8ff 50 {0, 0}, /* CT16B0, MR0 */
bogdanm 0:9b334a45a8ff 51 {0, 1}, /* CT16B0, MR1 */
bogdanm 0:9b334a45a8ff 52
bogdanm 0:9b334a45a8ff 53 {1, 0}, /* CT16B1, MR0 */
bogdanm 0:9b334a45a8ff 54 {1, 1}, /* CT16B1, MR1 */
bogdanm 0:9b334a45a8ff 55
bogdanm 0:9b334a45a8ff 56 {2, 2}, /* CT32B0, MR2 */
bogdanm 0:9b334a45a8ff 57 };
bogdanm 0:9b334a45a8ff 58
bogdanm 0:9b334a45a8ff 59 static LPC_TMR_TypeDef *Timers[3] = {
bogdanm 0:9b334a45a8ff 60 LPC_TMR16B0, LPC_TMR16B1,
bogdanm 0:9b334a45a8ff 61 LPC_TMR32B0
bogdanm 0:9b334a45a8ff 62 };
bogdanm 0:9b334a45a8ff 63
bogdanm 0:9b334a45a8ff 64 void pwmout_init(pwmout_t* obj, PinName pin) {
bogdanm 0:9b334a45a8ff 65 // determine the channel
bogdanm 0:9b334a45a8ff 66 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
bogdanm 0:9b334a45a8ff 67 MBED_ASSERT(pwm != (PWMName)NC);
bogdanm 0:9b334a45a8ff 68
bogdanm 0:9b334a45a8ff 69 obj->pwm = pwm;
bogdanm 0:9b334a45a8ff 70
bogdanm 0:9b334a45a8ff 71 // Timer registers
bogdanm 0:9b334a45a8ff 72 timer_mr tid = pwm_timer_map[pwm];
bogdanm 0:9b334a45a8ff 73 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 74
bogdanm 0:9b334a45a8ff 75 // Disable timer
bogdanm 0:9b334a45a8ff 76 timer->TCR = 0;
bogdanm 0:9b334a45a8ff 77
bogdanm 0:9b334a45a8ff 78 // Power the correspondent timer
bogdanm 0:9b334a45a8ff 79 LPC_SYSCON->SYSAHBCLKCTRL |= 1 << (tid.timer + 7);
bogdanm 0:9b334a45a8ff 80
bogdanm 0:9b334a45a8ff 81 /* Enable PWM function */
bogdanm 0:9b334a45a8ff 82 timer->PWMC = (1 << 3)|(1 << 2)|(1 << 1)|(1 << 0);
bogdanm 0:9b334a45a8ff 83
bogdanm 0:9b334a45a8ff 84 /* Reset Functionality on MR3 controlling the PWM period */
bogdanm 0:9b334a45a8ff 85 timer->MCR = 1 << 10;
bogdanm 0:9b334a45a8ff 86
bogdanm 0:9b334a45a8ff 87 if (timer == LPC_TMR16B0 || timer == LPC_TMR16B1) {
bogdanm 0:9b334a45a8ff 88 /* Set 16-bit timer prescaler to avoid timer expire for default 20ms */
bogdanm 0:9b334a45a8ff 89 /* This can be also modified by user application, but the prescaler value */
bogdanm 0:9b334a45a8ff 90 /* might be trade-off to timer accuracy */
bogdanm 0:9b334a45a8ff 91 timer->PR = 30;
bogdanm 0:9b334a45a8ff 92 }
bogdanm 0:9b334a45a8ff 93
bogdanm 0:9b334a45a8ff 94 // default to 20ms: standard for servos, and fine for e.g. brightness control
bogdanm 0:9b334a45a8ff 95 pwmout_period_ms(obj, 20);
bogdanm 0:9b334a45a8ff 96 pwmout_write (obj, 0);
bogdanm 0:9b334a45a8ff 97
bogdanm 0:9b334a45a8ff 98 // Wire pinout
bogdanm 0:9b334a45a8ff 99 pinmap_pinout(pin, PinMap_PWM);
bogdanm 0:9b334a45a8ff 100 }
bogdanm 0:9b334a45a8ff 101
bogdanm 0:9b334a45a8ff 102 void pwmout_free(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 103 // [TODO]
bogdanm 0:9b334a45a8ff 104 }
bogdanm 0:9b334a45a8ff 105
bogdanm 0:9b334a45a8ff 106 void pwmout_write(pwmout_t* obj, float value) {
bogdanm 0:9b334a45a8ff 107 if (value < 0.0f) {
bogdanm 0:9b334a45a8ff 108 value = 0.0;
bogdanm 0:9b334a45a8ff 109 } else if (value > 1.0f) {
bogdanm 0:9b334a45a8ff 110 value = 1.0;
bogdanm 0:9b334a45a8ff 111 }
bogdanm 0:9b334a45a8ff 112
bogdanm 0:9b334a45a8ff 113 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 0:9b334a45a8ff 114 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 115 uint32_t t_off = timer->MR3 - (uint32_t)((float)(timer->MR3) * value);
bogdanm 0:9b334a45a8ff 116 // to avoid spike pulse when duty is 0%
bogdanm 0:9b334a45a8ff 117 if (value == 0) {
bogdanm 0:9b334a45a8ff 118 t_off++;
bogdanm 0:9b334a45a8ff 119 }
bogdanm 0:9b334a45a8ff 120
bogdanm 0:9b334a45a8ff 121 timer->TCR = TCR_RESET;
bogdanm 0:9b334a45a8ff 122 timer->MR[tid.mr] = t_off;
bogdanm 0:9b334a45a8ff 123 timer->TCR = TCR_CNT_EN;
bogdanm 0:9b334a45a8ff 124 }
bogdanm 0:9b334a45a8ff 125
bogdanm 0:9b334a45a8ff 126 float pwmout_read(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 127 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 0:9b334a45a8ff 128 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 129
bogdanm 0:9b334a45a8ff 130 float v = (float)(timer->MR3 - timer->MR[tid.mr]) / (float)(timer->MR3);
bogdanm 0:9b334a45a8ff 131 if (timer->MR[tid.mr] > timer->MR3) {
bogdanm 0:9b334a45a8ff 132 v = 0.0f;
bogdanm 0:9b334a45a8ff 133 }
bogdanm 0:9b334a45a8ff 134 return (v > 1.0f) ? (1.0f) : (v);
bogdanm 0:9b334a45a8ff 135 }
bogdanm 0:9b334a45a8ff 136
bogdanm 0:9b334a45a8ff 137 void pwmout_period(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 138 pwmout_period_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 139 }
bogdanm 0:9b334a45a8ff 140
bogdanm 0:9b334a45a8ff 141 void pwmout_period_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 142 pwmout_period_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 143 }
bogdanm 0:9b334a45a8ff 144
bogdanm 0:9b334a45a8ff 145 // Set the PWM period, keeping the duty cycle the same.
bogdanm 0:9b334a45a8ff 146 void pwmout_period_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 147 int i = 0;
bogdanm 0:9b334a45a8ff 148 uint32_t period_ticks;
bogdanm 0:9b334a45a8ff 149
bogdanm 0:9b334a45a8ff 150 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 0:9b334a45a8ff 151 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 152 uint32_t old_period_ticks = timer->MR3;
bogdanm 0:9b334a45a8ff 153 period_ticks = (SystemCoreClock / 1000000 * us) / (timer->PR + 1);
bogdanm 0:9b334a45a8ff 154
bogdanm 0:9b334a45a8ff 155 timer->TCR = TCR_RESET;
bogdanm 0:9b334a45a8ff 156 timer->MR3 = period_ticks;
bogdanm 0:9b334a45a8ff 157
bogdanm 0:9b334a45a8ff 158 // Scale the pulse width to preserve the duty ratio
bogdanm 0:9b334a45a8ff 159 if (old_period_ticks > 0) {
bogdanm 0:9b334a45a8ff 160 for (i=0; i<3; i++) {
bogdanm 0:9b334a45a8ff 161 uint32_t t_off = period_ticks - (uint32_t)(((uint64_t)timer->MR[i] * (uint64_t)period_ticks) / (uint64_t)old_period_ticks);
bogdanm 0:9b334a45a8ff 162 timer->MR[i] = t_off;
bogdanm 0:9b334a45a8ff 163 }
bogdanm 0:9b334a45a8ff 164 }
bogdanm 0:9b334a45a8ff 165 timer->TCR = TCR_CNT_EN;
bogdanm 0:9b334a45a8ff 166 }
bogdanm 0:9b334a45a8ff 167
bogdanm 0:9b334a45a8ff 168 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 169 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 170 }
bogdanm 0:9b334a45a8ff 171
bogdanm 0:9b334a45a8ff 172 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 173 pwmout_pulsewidth_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 174 }
bogdanm 0:9b334a45a8ff 175
bogdanm 0:9b334a45a8ff 176 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 177 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 0:9b334a45a8ff 178 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 179 uint32_t t_on = (uint32_t)((((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000) / (timer->PR + 1));
bogdanm 0:9b334a45a8ff 180
bogdanm 0:9b334a45a8ff 181 timer->TCR = TCR_RESET;
bogdanm 0:9b334a45a8ff 182 if (t_on > timer->MR3) {
bogdanm 0:9b334a45a8ff 183 pwmout_period_us(obj, us);
bogdanm 0:9b334a45a8ff 184 }
bogdanm 0:9b334a45a8ff 185 uint32_t t_off = timer->MR3 - t_on;
bogdanm 0:9b334a45a8ff 186 timer->MR[tid.mr] = t_off;
bogdanm 0:9b334a45a8ff 187 timer->TCR = TCR_CNT_EN;
bogdanm 0:9b334a45a8ff 188 }