Marco Mayer / Mbed OS Queue

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mbed-os/targets/TARGET_NXP/TARGET_LPC15XX/pwmout_api.c@0:6bf0743ece18, 2020-03-28 (annotated)

Committer:
demayer
Date:
Sat Mar 28 15:28:19 2020 +0000
Revision:
0:6bf0743ece18
IMU Thread with an event-queue running parallel to handle tasks like a 5 times blinking LED. Button with interrupt detected.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
demayer 0:6bf0743ece18 1 /* mbed Microcontroller Library
demayer 0:6bf0743ece18 2 * Copyright (c) 2006-2013 ARM Limited
demayer 0:6bf0743ece18 3 *
demayer 0:6bf0743ece18 4 * Licensed under the Apache License, Version 2.0 (the "License");
demayer 0:6bf0743ece18 5 * you may not use this file except in compliance with the License.
demayer 0:6bf0743ece18 6 * You may obtain a copy of the License at
demayer 0:6bf0743ece18 7 *
demayer 0:6bf0743ece18 8 * http://www.apache.org/licenses/LICENSE-2.0
demayer 0:6bf0743ece18 9 *
demayer 0:6bf0743ece18 10 * Unless required by applicable law or agreed to in writing, software
demayer 0:6bf0743ece18 11 * distributed under the License is distributed on an "AS IS" BASIS,
demayer 0:6bf0743ece18 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
demayer 0:6bf0743ece18 13 * See the License for the specific language governing permissions and
demayer 0:6bf0743ece18 14 * limitations under the License.
demayer 0:6bf0743ece18 15 */
demayer 0:6bf0743ece18 16 #include "mbed_assert.h"
demayer 0:6bf0743ece18 17 #include "pwmout_api.h"
demayer 0:6bf0743ece18 18 #include "cmsis.h"
demayer 0:6bf0743ece18 19 #include "pinmap.h"
demayer 0:6bf0743ece18 20 #include "mbed_error.h"
demayer 0:6bf0743ece18 21
demayer 0:6bf0743ece18 22 static LPC_SCT0_Type *SCTs[4] = {
demayer 0:6bf0743ece18 23 (LPC_SCT0_Type*)LPC_SCT0,
demayer 0:6bf0743ece18 24 (LPC_SCT0_Type*)LPC_SCT1,
demayer 0:6bf0743ece18 25 (LPC_SCT0_Type*)LPC_SCT2,
demayer 0:6bf0743ece18 26 (LPC_SCT0_Type*)LPC_SCT3,
demayer 0:6bf0743ece18 27 };
demayer 0:6bf0743ece18 28
demayer 0:6bf0743ece18 29 // bit flags for used SCTs
demayer 0:6bf0743ece18 30 static unsigned char sct_used = (1 << 3);
demayer 0:6bf0743ece18 31 static int get_available_sct(void) {
demayer 0:6bf0743ece18 32 int i;
demayer 0:6bf0743ece18 33 for (i=0; i<4; i++) {
demayer 0:6bf0743ece18 34 if ((sct_used & (1 << i)) == 0)
demayer 0:6bf0743ece18 35 return i;
demayer 0:6bf0743ece18 36 }
demayer 0:6bf0743ece18 37 return -1;
demayer 0:6bf0743ece18 38 }
demayer 0:6bf0743ece18 39
demayer 0:6bf0743ece18 40 void pwmout_init(pwmout_t* obj, PinName pin) {
demayer 0:6bf0743ece18 41 MBED_ASSERT(pin != (uint32_t)NC);
demayer 0:6bf0743ece18 42
demayer 0:6bf0743ece18 43 int sct_n = get_available_sct();
demayer 0:6bf0743ece18 44 if (sct_n == -1) {
demayer 0:6bf0743ece18 45 error("No available SCT");
demayer 0:6bf0743ece18 46 }
demayer 0:6bf0743ece18 47
demayer 0:6bf0743ece18 48 sct_used |= (1 << sct_n);
demayer 0:6bf0743ece18 49 obj->pwm = SCTs[sct_n];
demayer 0:6bf0743ece18 50 obj->pwm_ch = sct_n;
demayer 0:6bf0743ece18 51
demayer 0:6bf0743ece18 52 LPC_SCT0_Type* pwm = obj->pwm;
demayer 0:6bf0743ece18 53
demayer 0:6bf0743ece18 54 // Enable the SCT clock
demayer 0:6bf0743ece18 55 LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << (obj->pwm_ch + 2));
demayer 0:6bf0743ece18 56
demayer 0:6bf0743ece18 57 // Clear peripheral reset the SCT:
demayer 0:6bf0743ece18 58 LPC_SYSCON->PRESETCTRL1 |= (1 << (obj->pwm_ch + 2));
demayer 0:6bf0743ece18 59 LPC_SYSCON->PRESETCTRL1 &= ~(1 << (obj->pwm_ch + 2));
demayer 0:6bf0743ece18 60
demayer 0:6bf0743ece18 61 switch(obj->pwm_ch) {
demayer 0:6bf0743ece18 62 case 0:
demayer 0:6bf0743ece18 63 // SCT0_OUT0
demayer 0:6bf0743ece18 64 LPC_SWM->PINASSIGN[7] &= ~0x0000FF00;
demayer 0:6bf0743ece18 65 LPC_SWM->PINASSIGN[7] |= (pin << 8);
demayer 0:6bf0743ece18 66 break;
demayer 0:6bf0743ece18 67 case 1:
demayer 0:6bf0743ece18 68 // SCT1_OUT0
demayer 0:6bf0743ece18 69 LPC_SWM->PINASSIGN[8] &= ~0x000000FF;
demayer 0:6bf0743ece18 70 LPC_SWM->PINASSIGN[8] |= (pin);
demayer 0:6bf0743ece18 71 break;
demayer 0:6bf0743ece18 72 case 2:
demayer 0:6bf0743ece18 73 // SCT2_OUT0
demayer 0:6bf0743ece18 74 LPC_SWM->PINASSIGN[8] &= ~0xFF000000;
demayer 0:6bf0743ece18 75 LPC_SWM->PINASSIGN[8] |= (pin << 24);
demayer 0:6bf0743ece18 76 break;
demayer 0:6bf0743ece18 77 case 3:
demayer 0:6bf0743ece18 78 // SCT3_OUT0
demayer 0:6bf0743ece18 79 LPC_SWM->PINASSIGN[9] &= ~0x00FF0000;
demayer 0:6bf0743ece18 80 LPC_SWM->PINASSIGN[9] |= (pin << 16);
demayer 0:6bf0743ece18 81 break;
demayer 0:6bf0743ece18 82 default:
demayer 0:6bf0743ece18 83 break;
demayer 0:6bf0743ece18 84 }
demayer 0:6bf0743ece18 85
demayer 0:6bf0743ece18 86 // Unified 32-bit counter, autolimit
demayer 0:6bf0743ece18 87 pwm->CONFIG |= ((0x3 << 17) | 0x01);
demayer 0:6bf0743ece18 88
demayer 0:6bf0743ece18 89 // halt and clear the counter
demayer 0:6bf0743ece18 90 pwm->CTRL |= (1 << 2) | (1 << 3);
demayer 0:6bf0743ece18 91
demayer 0:6bf0743ece18 92 pwm->OUT0_SET = (1 << 0); // event 0
demayer 0:6bf0743ece18 93 pwm->OUT0_CLR = (1 << 1); // event 1
demayer 0:6bf0743ece18 94 // Resolve conflicts on output 0 to set output
demayer 0:6bf0743ece18 95 // This allows duty cycle = 1.0 to work, where the MATCH registers for set and clear are equal
demayer 0:6bf0743ece18 96 pwm->RES = 0x01;
demayer 0:6bf0743ece18 97
demayer 0:6bf0743ece18 98 pwm->EV0_CTRL = (1 << 12);
demayer 0:6bf0743ece18 99 pwm->EV0_STATE = 0xFFFFFFFF;
demayer 0:6bf0743ece18 100 pwm->EV1_CTRL = (1 << 12) | (1 << 0);
demayer 0:6bf0743ece18 101 pwm->EV1_STATE = 0xFFFFFFFF;
demayer 0:6bf0743ece18 102
demayer 0:6bf0743ece18 103 // default to 20ms: standard for servos, and fine for e.g. brightness control
demayer 0:6bf0743ece18 104 pwmout_period_ms(obj, 20);
demayer 0:6bf0743ece18 105 pwmout_write (obj, 0);
demayer 0:6bf0743ece18 106 }
demayer 0:6bf0743ece18 107
demayer 0:6bf0743ece18 108 void pwmout_free(pwmout_t* obj) {
demayer 0:6bf0743ece18 109 // Disable the SCT clock
demayer 0:6bf0743ece18 110 LPC_SYSCON->SYSAHBCLKCTRL1 &= ~(1 << (obj->pwm_ch + 2));
demayer 0:6bf0743ece18 111 sct_used &= ~(1 << obj->pwm_ch);
demayer 0:6bf0743ece18 112 }
demayer 0:6bf0743ece18 113
demayer 0:6bf0743ece18 114 void pwmout_write(pwmout_t* obj, float value) {
demayer 0:6bf0743ece18 115 LPC_SCT0_Type* pwm = obj->pwm;
demayer 0:6bf0743ece18 116 if (value < 0.0f) {
demayer 0:6bf0743ece18 117 value = 0.0;
demayer 0:6bf0743ece18 118 } else if (value > 1.0f) {
demayer 0:6bf0743ece18 119 value = 1.0;
demayer 0:6bf0743ece18 120 }
demayer 0:6bf0743ece18 121 uint32_t t_on = (uint32_t)((float)(pwm->MATCHREL0 + 1) * value);
demayer 0:6bf0743ece18 122 if (t_on > 0) {
demayer 0:6bf0743ece18 123 pwm->MATCHREL1 = t_on - 1;
demayer 0:6bf0743ece18 124
demayer 0:6bf0743ece18 125 // Un-halt the timer and ensure the new pulse-width takes immediate effect if necessary
demayer 0:6bf0743ece18 126 if (pwm->CTRL & (1 << 2)) {
demayer 0:6bf0743ece18 127 pwm->MATCH1 = pwm->MATCHREL1;
demayer 0:6bf0743ece18 128 pwm->CTRL &= ~(1 << 2);
demayer 0:6bf0743ece18 129 }
demayer 0:6bf0743ece18 130 } else {
demayer 0:6bf0743ece18 131 // Halt the timer and force the output low
demayer 0:6bf0743ece18 132 pwm->CTRL |= (1 << 2) | (1 << 3);
demayer 0:6bf0743ece18 133 pwm->OUTPUT = 0x00000000;
demayer 0:6bf0743ece18 134 }
demayer 0:6bf0743ece18 135 }
demayer 0:6bf0743ece18 136
demayer 0:6bf0743ece18 137 float pwmout_read(pwmout_t* obj) {
demayer 0:6bf0743ece18 138 LPC_SCT0_Type* pwm = obj->pwm;
demayer 0:6bf0743ece18 139 uint32_t t_off = pwm->MATCHREL0 + 1;
demayer 0:6bf0743ece18 140 uint32_t t_on = (!(pwm->CTRL & (1 << 2))) ? pwm->MATCHREL1 + 1 : 0;
demayer 0:6bf0743ece18 141 float v = (float)t_on/(float)t_off;
demayer 0:6bf0743ece18 142 return (v > 1.0f) ? (1.0f) : (v);
demayer 0:6bf0743ece18 143 }
demayer 0:6bf0743ece18 144
demayer 0:6bf0743ece18 145 void pwmout_period(pwmout_t* obj, float seconds) {
demayer 0:6bf0743ece18 146 pwmout_period_us(obj, seconds * 1000000.0f);
demayer 0:6bf0743ece18 147 }
demayer 0:6bf0743ece18 148
demayer 0:6bf0743ece18 149 void pwmout_period_ms(pwmout_t* obj, int ms) {
demayer 0:6bf0743ece18 150 pwmout_period_us(obj, ms * 1000);
demayer 0:6bf0743ece18 151 }
demayer 0:6bf0743ece18 152
demayer 0:6bf0743ece18 153 // Set the PWM period, keeping the duty cycle the same.
demayer 0:6bf0743ece18 154 void pwmout_period_us(pwmout_t* obj, int us) {
demayer 0:6bf0743ece18 155 LPC_SCT0_Type* pwm = obj->pwm;
demayer 0:6bf0743ece18 156 uint32_t t_off = pwm->MATCHREL0 + 1;
demayer 0:6bf0743ece18 157 uint32_t t_on = (!(pwm->CTRL & (1 << 2))) ? pwm->MATCHREL1 + 1 : 0;
demayer 0:6bf0743ece18 158 float v = (float)t_on/(float)t_off;
demayer 0:6bf0743ece18 159 uint32_t period_ticks = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000);
demayer 0:6bf0743ece18 160 uint32_t pulsewidth_ticks = period_ticks * v;
demayer 0:6bf0743ece18 161 pwm->MATCHREL0 = period_ticks - 1;
demayer 0:6bf0743ece18 162 if (pulsewidth_ticks > 0) {
demayer 0:6bf0743ece18 163 pwm->MATCHREL1 = pulsewidth_ticks - 1;
demayer 0:6bf0743ece18 164
demayer 0:6bf0743ece18 165 // Un-halt the timer and ensure the new period & pulse-width take immediate effect if necessary
demayer 0:6bf0743ece18 166 if (pwm->CTRL & (1 << 2)) {
demayer 0:6bf0743ece18 167 pwm->MATCH0 = pwm->MATCHREL0;
demayer 0:6bf0743ece18 168 pwm->MATCH1 = pwm->MATCHREL1;
demayer 0:6bf0743ece18 169 pwm->CTRL &= ~(1 << 2);
demayer 0:6bf0743ece18 170 }
demayer 0:6bf0743ece18 171 } else {
demayer 0:6bf0743ece18 172 // Halt the timer and force the output low
demayer 0:6bf0743ece18 173 pwm->CTRL |= (1 << 2) | (1 << 3);
demayer 0:6bf0743ece18 174 pwm->OUTPUT = 0x00000000;
demayer 0:6bf0743ece18 175
demayer 0:6bf0743ece18 176 // Ensure the new period will take immediate effect when the timer is un-halted
demayer 0:6bf0743ece18 177 pwm->MATCH0 = pwm->MATCHREL0;
demayer 0:6bf0743ece18 178 }
demayer 0:6bf0743ece18 179 }
demayer 0:6bf0743ece18 180
demayer 0:6bf0743ece18 181 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
demayer 0:6bf0743ece18 182 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
demayer 0:6bf0743ece18 183 }
demayer 0:6bf0743ece18 184
demayer 0:6bf0743ece18 185 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
demayer 0:6bf0743ece18 186 pwmout_pulsewidth_us(obj, ms * 1000);
demayer 0:6bf0743ece18 187 }
demayer 0:6bf0743ece18 188
demayer 0:6bf0743ece18 189 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
demayer 0:6bf0743ece18 190 LPC_SCT0_Type* pwm = obj->pwm;
demayer 0:6bf0743ece18 191 if (us > 0) {
demayer 0:6bf0743ece18 192 pwm->MATCHREL1 = (uint32_t)(((uint64_t)SystemCoreClock * (uint64_t)us) / (uint64_t)1000000) - 1;
demayer 0:6bf0743ece18 193
demayer 0:6bf0743ece18 194 // Un-halt the timer and ensure the new pulse-width takes immediate effect if necessary
demayer 0:6bf0743ece18 195 if (pwm->CTRL & (1 << 2)) {
demayer 0:6bf0743ece18 196 pwm->MATCH1 = pwm->MATCHREL1;
demayer 0:6bf0743ece18 197 pwm->CTRL &= ~(1 << 2);
demayer 0:6bf0743ece18 198 }
demayer 0:6bf0743ece18 199 } else {
demayer 0:6bf0743ece18 200 // Halt the timer and force the output low
demayer 0:6bf0743ece18 201 pwm->CTRL |= (1 << 2) | (1 << 3);
demayer 0:6bf0743ece18 202 pwm->OUTPUT = 0x00000000;
demayer 0:6bf0743ece18 203 }
demayer 0:6bf0743ece18 204 }
demayer 0:6bf0743ece18 205