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Last commit 20 Feb 2019 by mbed official

targets/hal/TARGET_NXP/TARGET_LPC11XX/pwmout_api.c@19:398f4c622e1b, 2013-08-19 (annotated)

Committer:
bogdanm
Date:
Mon Aug 19 18:17:02 2013 +0300
Revision:
19:398f4c622e1b
Child:
20:4263a77256ae
Sync with official mbed library release 66

Who changed what in which revision?

UserRevisionLine numberNew contents of line
bogdanm 19:398f4c622e1b 1 /* mbed Microcontroller Library
bogdanm 19:398f4c622e1b 2 * Copyright (c) 2006-2013 ARM Limited
bogdanm 19:398f4c622e1b 3 *
bogdanm 19:398f4c622e1b 4 * Licensed under the Apache License, Version 2.0 (the "License");
bogdanm 19:398f4c622e1b 5 * you may not use this file except in compliance with the License.
bogdanm 19:398f4c622e1b 6 * You may obtain a copy of the License at
bogdanm 19:398f4c622e1b 7 *
bogdanm 19:398f4c622e1b 8 * http://www.apache.org/licenses/LICENSE-2.0
bogdanm 19:398f4c622e1b 9 *
bogdanm 19:398f4c622e1b 10 * Unless required by applicable law or agreed to in writing, software
bogdanm 19:398f4c622e1b 11 * distributed under the License is distributed on an "AS IS" BASIS,
bogdanm 19:398f4c622e1b 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
bogdanm 19:398f4c622e1b 13 * See the License for the specific language governing permissions and
bogdanm 19:398f4c622e1b 14 * limitations under the License.
bogdanm 19:398f4c622e1b 15 */
bogdanm 19:398f4c622e1b 16 #include "pwmout_api.h"
bogdanm 19:398f4c622e1b 17 #include "cmsis.h"
bogdanm 19:398f4c622e1b 18 #include "pinmap.h"
bogdanm 19:398f4c622e1b 19 #include "error.h"
bogdanm 19:398f4c622e1b 20
bogdanm 19:398f4c622e1b 21 #define TCR_CNT_EN 0x00000001
bogdanm 19:398f4c622e1b 22 #define TCR_RESET 0x00000002
bogdanm 19:398f4c622e1b 23
bogdanm 19:398f4c622e1b 24 /* To have a PWM where we can change both the period and the duty cycle,
bogdanm 19:398f4c622e1b 25 * we need an entire timer. With the following conventions:
bogdanm 19:398f4c622e1b 26 * * MR3 is used for the PWM period
bogdanm 19:398f4c622e1b 27 * * MR0, MR1, MR2 are used for the duty cycle
bogdanm 19:398f4c622e1b 28 */
bogdanm 19:398f4c622e1b 29 static const PinMap PinMap_PWM[] = {
bogdanm 19:398f4c622e1b 30 /* CT16B0 */
bogdanm 19:398f4c622e1b 31 {P0_8 , PWM_1, 0x02}, /* MR0 */
bogdanm 19:398f4c622e1b 32 {P0_9 , PWM_2, 0x02}, /* MR1 */
bogdanm 19:398f4c622e1b 33
bogdanm 19:398f4c622e1b 34 /* CT16B1 */
bogdanm 19:398f4c622e1b 35 {P1_9 , PWM_4, 0x01}, /* MR0 */
bogdanm 19:398f4c622e1b 36 {P1_10, PWM_5, 0x02}, /* MR1 */
bogdanm 19:398f4c622e1b 37
bogdanm 19:398f4c622e1b 38 /* CT32B0 */
bogdanm 19:398f4c622e1b 39 {P1_6 , PWM_6, 0x02}, /* MR0 */
bogdanm 19:398f4c622e1b 40 {P1_7 , PWM_7, 0x02}, /* MR1 */
bogdanm 19:398f4c622e1b 41 {P0_1 , PWM_8, 0x02}, /* MR2 */
bogdanm 19:398f4c622e1b 42
bogdanm 19:398f4c622e1b 43 /* CT32B1 */
bogdanm 19:398f4c622e1b 44 {P1_1 , PWM_9 ,0x03}, /* MR0 */
bogdanm 19:398f4c622e1b 45 {P1_2 , PWM_10,0x03}, /* MR1 */
bogdanm 19:398f4c622e1b 46
bogdanm 19:398f4c622e1b 47 {NC , NC ,0x00}
bogdanm 19:398f4c622e1b 48 };
bogdanm 19:398f4c622e1b 49
bogdanm 19:398f4c622e1b 50 typedef struct {
bogdanm 19:398f4c622e1b 51 uint8_t timer;
bogdanm 19:398f4c622e1b 52 uint8_t mr;
bogdanm 19:398f4c622e1b 53 } timer_mr;
bogdanm 19:398f4c622e1b 54
bogdanm 19:398f4c622e1b 55 static timer_mr pwm_timer_map[9] = {
bogdanm 19:398f4c622e1b 56 {0, 0}, /* CT16B0, MR0 */
bogdanm 19:398f4c622e1b 57 {0, 1}, /* CT16B0, MR1 */
bogdanm 19:398f4c622e1b 58
bogdanm 19:398f4c622e1b 59 {1, 0}, /* CT16B1, MR0 */
bogdanm 19:398f4c622e1b 60 {1, 1}, /* CT16B1, MR1 */
bogdanm 19:398f4c622e1b 61
bogdanm 19:398f4c622e1b 62 {2, 0}, /* CT32B0, MR0 */
bogdanm 19:398f4c622e1b 63 {2, 1}, /* CT32B0, MR1 */
bogdanm 19:398f4c622e1b 64 {2, 2}, /* CT32B0, MR2 */
bogdanm 19:398f4c622e1b 65
bogdanm 19:398f4c622e1b 66 {3, 0}, /* CT32B1, MR0 */
bogdanm 19:398f4c622e1b 67 {3, 1}, /* CT32B1, MR1 */
bogdanm 19:398f4c622e1b 68 };
bogdanm 19:398f4c622e1b 69
bogdanm 19:398f4c622e1b 70 static LPC_TMR_TypeDef *Timers[4] = {
bogdanm 19:398f4c622e1b 71 LPC_TMR16B0, LPC_TMR16B1,
bogdanm 19:398f4c622e1b 72 LPC_TMR32B0, LPC_TMR32B1
bogdanm 19:398f4c622e1b 73 };
bogdanm 19:398f4c622e1b 74
bogdanm 19:398f4c622e1b 75 static unsigned int pwm_clock_mhz;
bogdanm 19:398f4c622e1b 76
bogdanm 19:398f4c622e1b 77 void pwmout_init(pwmout_t* obj, PinName pin) {
bogdanm 19:398f4c622e1b 78 // determine the channel
bogdanm 19:398f4c622e1b 79 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
bogdanm 19:398f4c622e1b 80 if (pwm == (uint32_t)NC)
bogdanm 19:398f4c622e1b 81 error("PwmOut pin mapping failed");
bogdanm 19:398f4c622e1b 82
bogdanm 19:398f4c622e1b 83 obj->pwm = pwm;
bogdanm 19:398f4c622e1b 84
bogdanm 19:398f4c622e1b 85 // Timer registers
bogdanm 19:398f4c622e1b 86 timer_mr tid = pwm_timer_map[pwm];
bogdanm 19:398f4c622e1b 87 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 19:398f4c622e1b 88
bogdanm 19:398f4c622e1b 89 // Disable timer
bogdanm 19:398f4c622e1b 90 timer->TCR = 0;
bogdanm 19:398f4c622e1b 91
bogdanm 19:398f4c622e1b 92 // Power the correspondent timer
bogdanm 19:398f4c622e1b 93 LPC_SYSCON->SYSAHBCLKCTRL |= 1 << (tid.timer + 7);
bogdanm 19:398f4c622e1b 94
bogdanm 19:398f4c622e1b 95 /* Enable PWM function */
bogdanm 19:398f4c622e1b 96 timer->PWMC = (1 << 3)|(1 << 2)|(1 << 1)|(1 << 0);
bogdanm 19:398f4c622e1b 97
bogdanm 19:398f4c622e1b 98 /* Reset Functionality on MR3 controlling the PWM period */
bogdanm 19:398f4c622e1b 99 timer->MCR = 1 << 10;
bogdanm 19:398f4c622e1b 100
bogdanm 19:398f4c622e1b 101 pwm_clock_mhz = SystemCoreClock / 1000000;
bogdanm 19:398f4c622e1b 102
bogdanm 19:398f4c622e1b 103 // default to 20ms: standard for servos, and fine for e.g. brightness control
bogdanm 19:398f4c622e1b 104 pwmout_period_ms(obj, 20);
bogdanm 19:398f4c622e1b 105 pwmout_write (obj, 0);
bogdanm 19:398f4c622e1b 106
bogdanm 19:398f4c622e1b 107 // Wire pinout
bogdanm 19:398f4c622e1b 108 pinmap_pinout(pin, PinMap_PWM);
bogdanm 19:398f4c622e1b 109 }
bogdanm 19:398f4c622e1b 110
bogdanm 19:398f4c622e1b 111 void pwmout_free(pwmout_t* obj) {
bogdanm 19:398f4c622e1b 112 // [TODO]
bogdanm 19:398f4c622e1b 113 }
bogdanm 19:398f4c622e1b 114
bogdanm 19:398f4c622e1b 115 void pwmout_write(pwmout_t* obj, float value) {
bogdanm 19:398f4c622e1b 116 if (value < 0.0f) {
bogdanm 19:398f4c622e1b 117 value = 0.0;
bogdanm 19:398f4c622e1b 118 } else if (value > 1.0f) {
bogdanm 19:398f4c622e1b 119 value = 1.0;
bogdanm 19:398f4c622e1b 120 }
bogdanm 19:398f4c622e1b 121
bogdanm 19:398f4c622e1b 122 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 19:398f4c622e1b 123 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 19:398f4c622e1b 124 uint32_t t_off = timer->MR3 - (uint32_t)((float)(timer->MR3) * value);
bogdanm 19:398f4c622e1b 125
bogdanm 19:398f4c622e1b 126 timer->TCR = TCR_RESET;
bogdanm 19:398f4c622e1b 127 timer->MR[tid.mr] = t_off;
bogdanm 19:398f4c622e1b 128 timer->TCR = TCR_CNT_EN;
bogdanm 19:398f4c622e1b 129 }
bogdanm 19:398f4c622e1b 130
bogdanm 19:398f4c622e1b 131 float pwmout_read(pwmout_t* obj) {
bogdanm 19:398f4c622e1b 132 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 19:398f4c622e1b 133 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 19:398f4c622e1b 134
bogdanm 19:398f4c622e1b 135 float v = (float)(timer->MR3 - timer->MR[tid.mr]) / (float)(timer->MR3);
bogdanm 19:398f4c622e1b 136 return (v > 1.0f) ? (1.0f) : (v);
bogdanm 19:398f4c622e1b 137 }
bogdanm 19:398f4c622e1b 138
bogdanm 19:398f4c622e1b 139 void pwmout_period(pwmout_t* obj, float seconds) {
bogdanm 19:398f4c622e1b 140 pwmout_period_us(obj, seconds * 1000000.0f);
bogdanm 19:398f4c622e1b 141 }
bogdanm 19:398f4c622e1b 142
bogdanm 19:398f4c622e1b 143 void pwmout_period_ms(pwmout_t* obj, int ms) {
bogdanm 19:398f4c622e1b 144 pwmout_period_us(obj, ms * 1000);
bogdanm 19:398f4c622e1b 145 }
bogdanm 19:398f4c622e1b 146
bogdanm 19:398f4c622e1b 147 // Set the PWM period, keeping the duty cycle the same.
bogdanm 19:398f4c622e1b 148 void pwmout_period_us(pwmout_t* obj, int us) {
bogdanm 19:398f4c622e1b 149 int i = 0;
bogdanm 19:398f4c622e1b 150 uint32_t period_ticks = pwm_clock_mhz * us;
bogdanm 19:398f4c622e1b 151
bogdanm 19:398f4c622e1b 152 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 19:398f4c622e1b 153 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 19:398f4c622e1b 154 uint32_t old_period_ticks = timer->MR3;
bogdanm 19:398f4c622e1b 155
bogdanm 19:398f4c622e1b 156 timer->TCR = TCR_RESET;
bogdanm 19:398f4c622e1b 157 timer->MR3 = period_ticks;
bogdanm 19:398f4c622e1b 158
bogdanm 19:398f4c622e1b 159 // Scale the pulse width to preserve the duty ratio
bogdanm 19:398f4c622e1b 160 if (old_period_ticks > 0) {
bogdanm 19:398f4c622e1b 161 for (i=0; i<3; i++) {
bogdanm 19:398f4c622e1b 162 uint32_t t_off = period_ticks - (uint32_t)(((uint64_t)timer->MR[i] * (uint64_t)period_ticks) / (uint64_t)old_period_ticks);
bogdanm 19:398f4c622e1b 163 timer->MR[i] = t_off;
bogdanm 19:398f4c622e1b 164 }
bogdanm 19:398f4c622e1b 165 }
bogdanm 19:398f4c622e1b 166 timer->TCR = TCR_CNT_EN;
bogdanm 19:398f4c622e1b 167 }
bogdanm 19:398f4c622e1b 168
bogdanm 19:398f4c622e1b 169 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
bogdanm 19:398f4c622e1b 170 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
bogdanm 19:398f4c622e1b 171 }
bogdanm 19:398f4c622e1b 172
bogdanm 19:398f4c622e1b 173 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
bogdanm 19:398f4c622e1b 174 pwmout_pulsewidth_us(obj, ms * 1000);
bogdanm 19:398f4c622e1b 175 }
bogdanm 19:398f4c622e1b 176
bogdanm 19:398f4c622e1b 177 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
bogdanm 19:398f4c622e1b 178 uint32_t t_on = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000);
bogdanm 19:398f4c622e1b 179 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 19:398f4c622e1b 180 LPC_TMR_TypeDef *timer = Timers[tid.timer];
bogdanm 19:398f4c622e1b 181
bogdanm 19:398f4c622e1b 182 timer->TCR = TCR_RESET;
bogdanm 19:398f4c622e1b 183 if (t_on > timer->MR3) {
bogdanm 19:398f4c622e1b 184 pwmout_period_us(obj, us);
bogdanm 19:398f4c622e1b 185 }
bogdanm 19:398f4c622e1b 186 uint32_t t_off = timer->MR3 - t_on;
bogdanm 19:398f4c622e1b 187 timer->MR[tid.mr] = t_off;
bogdanm 19:398f4c622e1b 188 timer->TCR = TCR_CNT_EN;
bogdanm 19:398f4c622e1b 189 }