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targets/hal/TARGET_NXP/TARGET_LPC13XX/pwmout_api.c@0:9b334a45a8ff, 2015-10-01 (annotated)

Committer:
bogdanm
Date:
Thu Oct 01 15:25:22 2015 +0300
Revision:
0:9b334a45a8ff
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, 2}, {P1_13, PWM_1, 2}, /* MR0 */
bogdanm 0:9b334a45a8ff 32 {P0_9 , PWM_2, 2}, {P1_14, PWM_2, 2}, /* MR1 */
bogdanm 0:9b334a45a8ff 33 {P0_10, PWM_3, 3}, {P1_15, PWM_3, 2}, /* MR2 */
bogdanm 0:9b334a45a8ff 34
bogdanm 0:9b334a45a8ff 35 /* CT16B1 */
bogdanm 0:9b334a45a8ff 36 {P0_21, PWM_4, 1}, /* MR0 */
bogdanm 0:9b334a45a8ff 37 {P0_22, PWM_5, 2}, {P1_23, PWM_5, 1}, /* MR1 */
bogdanm 0:9b334a45a8ff 38
bogdanm 0:9b334a45a8ff 39 /* CT32B0 */
bogdanm 0:9b334a45a8ff 40 {P0_18, PWM_6, 2}, {P1_24, PWM_6, 1}, /* MR0 */
bogdanm 0:9b334a45a8ff 41 {P0_19, PWM_7, 2}, {P1_25, PWM_7, 1}, /* MR1 */
bogdanm 0:9b334a45a8ff 42 {P0_1 , PWM_8, 2}, {P1_26, PWM_8, 1}, /* MR2 */
bogdanm 0:9b334a45a8ff 43
bogdanm 0:9b334a45a8ff 44 /* CT32B1 */
bogdanm 0:9b334a45a8ff 45 {P0_13, PWM_9 , 3}, //{P1_0, PWM_9 , 1}, /* MR0 */
bogdanm 0:9b334a45a8ff 46 {P0_14, PWM_10, 3}, //{P1_1, PWM_10, 1}, /* MR1 */
bogdanm 0:9b334a45a8ff 47 {P0_15, PWM_11, 3}, //{P1_2, PWM_11, 1}, /* MR2 */
bogdanm 0:9b334a45a8ff 48
bogdanm 0:9b334a45a8ff 49 {NC, NC, 0}
bogdanm 0:9b334a45a8ff 50 };
bogdanm 0:9b334a45a8ff 51
bogdanm 0:9b334a45a8ff 52 typedef struct {
bogdanm 0:9b334a45a8ff 53 uint8_t timer;
bogdanm 0:9b334a45a8ff 54 uint8_t mr;
bogdanm 0:9b334a45a8ff 55 } timer_mr;
bogdanm 0:9b334a45a8ff 56
bogdanm 0:9b334a45a8ff 57 static timer_mr pwm_timer_map[11] = {
bogdanm 0:9b334a45a8ff 58 {0, 0}, {0, 1}, {0, 2},
bogdanm 0:9b334a45a8ff 59 {1, 0}, {1, 1},
bogdanm 0:9b334a45a8ff 60 {2, 0}, {2, 1}, {2, 2},
bogdanm 0:9b334a45a8ff 61 {3, 0}, {3, 1}, {3, 2},
bogdanm 0:9b334a45a8ff 62 };
bogdanm 0:9b334a45a8ff 63
bogdanm 0:9b334a45a8ff 64 static LPC_CTxxBx_Type *Timers[4] = {
bogdanm 0:9b334a45a8ff 65 LPC_CT16B0, LPC_CT16B1,
bogdanm 0:9b334a45a8ff 66 LPC_CT32B0, LPC_CT32B1
bogdanm 0:9b334a45a8ff 67 };
bogdanm 0:9b334a45a8ff 68
bogdanm 0:9b334a45a8ff 69 static unsigned int pwm_clock_mhz;
bogdanm 0:9b334a45a8ff 70
bogdanm 0:9b334a45a8ff 71 void pwmout_init(pwmout_t* obj, PinName pin) {
bogdanm 0:9b334a45a8ff 72 // determine the channel
bogdanm 0:9b334a45a8ff 73 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
bogdanm 0:9b334a45a8ff 74 MBED_ASSERT(pwm != (uint32_t)NC);
bogdanm 0:9b334a45a8ff 75
bogdanm 0:9b334a45a8ff 76 obj->pwm = pwm;
bogdanm 0:9b334a45a8ff 77
bogdanm 0:9b334a45a8ff 78 // Timer registers
bogdanm 0:9b334a45a8ff 79 timer_mr tid = pwm_timer_map[pwm];
bogdanm 0:9b334a45a8ff 80 LPC_CTxxBx_Type *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 81
bogdanm 0:9b334a45a8ff 82 // Disable timer
bogdanm 0:9b334a45a8ff 83 timer->TCR = 0;
bogdanm 0:9b334a45a8ff 84
bogdanm 0:9b334a45a8ff 85 // Power the correspondent timer
bogdanm 0:9b334a45a8ff 86 LPC_SYSCON->SYSAHBCLKCTRL |= 1 << (tid.timer + 7);
bogdanm 0:9b334a45a8ff 87
bogdanm 0:9b334a45a8ff 88 /* Enable PWM function */
bogdanm 0:9b334a45a8ff 89 timer->PWMC = (1 << 3)|(1 << 2)|(1 << 1)|(1 << 0);
bogdanm 0:9b334a45a8ff 90
bogdanm 0:9b334a45a8ff 91 /* Reset Functionality on MR3 controlling the PWM period */
bogdanm 0:9b334a45a8ff 92 timer->MCR = 1 << 10;
bogdanm 0:9b334a45a8ff 93
bogdanm 0:9b334a45a8ff 94 pwm_clock_mhz = SystemCoreClock / 1000000;
bogdanm 0:9b334a45a8ff 95
bogdanm 0:9b334a45a8ff 96 // default to 20ms: standard for servos, and fine for e.g. brightness control
bogdanm 0:9b334a45a8ff 97 pwmout_period_ms(obj, 20);
bogdanm 0:9b334a45a8ff 98 pwmout_write (obj, 0);
bogdanm 0:9b334a45a8ff 99
bogdanm 0:9b334a45a8ff 100 // Wire pinout
bogdanm 0:9b334a45a8ff 101 pinmap_pinout(pin, PinMap_PWM);
bogdanm 0:9b334a45a8ff 102 }
bogdanm 0:9b334a45a8ff 103
bogdanm 0:9b334a45a8ff 104 void pwmout_free(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 105 // [TODO]
bogdanm 0:9b334a45a8ff 106 }
bogdanm 0:9b334a45a8ff 107
bogdanm 0:9b334a45a8ff 108 void pwmout_write(pwmout_t* obj, float value) {
bogdanm 0:9b334a45a8ff 109 if (value < 0.0f) {
bogdanm 0:9b334a45a8ff 110 value = 0.0;
bogdanm 0:9b334a45a8ff 111 } else if (value > 1.0f) {
bogdanm 0:9b334a45a8ff 112 value = 1.0;
bogdanm 0:9b334a45a8ff 113 }
bogdanm 0:9b334a45a8ff 114
bogdanm 0:9b334a45a8ff 115 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 0:9b334a45a8ff 116 LPC_CTxxBx_Type *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 117 uint32_t t_off = timer->MR3 - (uint32_t)((float)(timer->MR3) * value);
bogdanm 0:9b334a45a8ff 118
bogdanm 0:9b334a45a8ff 119 timer->MR[tid.mr] = t_off;
bogdanm 0:9b334a45a8ff 120 }
bogdanm 0:9b334a45a8ff 121
bogdanm 0:9b334a45a8ff 122 float pwmout_read(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 123 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 0:9b334a45a8ff 124 LPC_CTxxBx_Type *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 125
bogdanm 0:9b334a45a8ff 126 float v = (float)(timer->MR3 - timer->MR[tid.mr]) / (float)(timer->MR3);
bogdanm 0:9b334a45a8ff 127 return (v > 1.0f) ? (1.0f) : (v);
bogdanm 0:9b334a45a8ff 128 }
bogdanm 0:9b334a45a8ff 129
bogdanm 0:9b334a45a8ff 130 void pwmout_period(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 131 pwmout_period_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 132 }
bogdanm 0:9b334a45a8ff 133
bogdanm 0:9b334a45a8ff 134 void pwmout_period_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 135 pwmout_period_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 136 }
bogdanm 0:9b334a45a8ff 137
bogdanm 0:9b334a45a8ff 138 // Set the PWM period, keeping the duty cycle the same.
bogdanm 0:9b334a45a8ff 139 void pwmout_period_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 140 int i = 0;
bogdanm 0:9b334a45a8ff 141 uint32_t period_ticks = pwm_clock_mhz * us;
bogdanm 0:9b334a45a8ff 142
bogdanm 0:9b334a45a8ff 143 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 0:9b334a45a8ff 144 LPC_CTxxBx_Type *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 145 uint32_t old_period_ticks = timer->MR3;
bogdanm 0:9b334a45a8ff 146
bogdanm 0:9b334a45a8ff 147 timer->TCR = TCR_RESET;
bogdanm 0:9b334a45a8ff 148 timer->MR3 = period_ticks;
bogdanm 0:9b334a45a8ff 149
bogdanm 0:9b334a45a8ff 150 // Scale the pulse width to preserve the duty ratio
bogdanm 0:9b334a45a8ff 151 if (old_period_ticks > 0) {
bogdanm 0:9b334a45a8ff 152 for (i=0; i<3; i++) {
bogdanm 0:9b334a45a8ff 153 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 154 timer->MR[i] = t_off;
bogdanm 0:9b334a45a8ff 155 }
bogdanm 0:9b334a45a8ff 156 }
bogdanm 0:9b334a45a8ff 157 timer->TCR = TCR_CNT_EN;
bogdanm 0:9b334a45a8ff 158 }
bogdanm 0:9b334a45a8ff 159
bogdanm 0:9b334a45a8ff 160 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 161 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 162 }
bogdanm 0:9b334a45a8ff 163
bogdanm 0:9b334a45a8ff 164 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 165 pwmout_pulsewidth_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 166 }
bogdanm 0:9b334a45a8ff 167
bogdanm 0:9b334a45a8ff 168 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 169 uint32_t t_on = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000);
bogdanm 0:9b334a45a8ff 170 timer_mr tid = pwm_timer_map[obj->pwm];
bogdanm 0:9b334a45a8ff 171 LPC_CTxxBx_Type *timer = Timers[tid.timer];
bogdanm 0:9b334a45a8ff 172
bogdanm 0:9b334a45a8ff 173 timer->TCR = TCR_RESET;
bogdanm 0:9b334a45a8ff 174 if (t_on > timer->MR3) {
bogdanm 0:9b334a45a8ff 175 pwmout_period_us(obj, us);
bogdanm 0:9b334a45a8ff 176 }
bogdanm 0:9b334a45a8ff 177 uint32_t t_off = timer->MR3 - t_on;
bogdanm 0:9b334a45a8ff 178 timer->MR[tid.mr] = t_off;
bogdanm 0:9b334a45a8ff 179 timer->TCR = TCR_CNT_EN;
bogdanm 0:9b334a45a8ff 180 }