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targets/hal/TARGET_NXP/TARGET_LPC15XX/pwmout_api.c@0:9b334a45a8ff, 2015-10-01 (annotated)

Committer:
bogdanm
Date:
Thu Oct 01 15:25:22 2015 +0300
Revision:
0:9b334a45a8ff
Child:
57:791e51e3acc9
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 #include "mbed_error.h"
bogdanm 0:9b334a45a8ff 21
bogdanm 0:9b334a45a8ff 22 static LPC_SCT0_Type *SCTs[4] = {
bogdanm 0:9b334a45a8ff 23 (LPC_SCT0_Type*)LPC_SCT0,
bogdanm 0:9b334a45a8ff 24 (LPC_SCT0_Type*)LPC_SCT1,
bogdanm 0:9b334a45a8ff 25 (LPC_SCT0_Type*)LPC_SCT2,
bogdanm 0:9b334a45a8ff 26 (LPC_SCT0_Type*)LPC_SCT3,
bogdanm 0:9b334a45a8ff 27 };
bogdanm 0:9b334a45a8ff 28
bogdanm 0:9b334a45a8ff 29 // bit flags for used SCTs
bogdanm 0:9b334a45a8ff 30 static unsigned char sct_used = 0;
bogdanm 0:9b334a45a8ff 31 static int get_available_sct(void) {
bogdanm 0:9b334a45a8ff 32 int i;
bogdanm 0:9b334a45a8ff 33 for (i=0; i<4; i++) {
bogdanm 0:9b334a45a8ff 34 if ((sct_used & (1 << i)) == 0)
bogdanm 0:9b334a45a8ff 35 return i;
bogdanm 0:9b334a45a8ff 36 }
bogdanm 0:9b334a45a8ff 37 return -1;
bogdanm 0:9b334a45a8ff 38 }
bogdanm 0:9b334a45a8ff 39
bogdanm 0:9b334a45a8ff 40 void pwmout_init(pwmout_t* obj, PinName pin) {
bogdanm 0:9b334a45a8ff 41 MBED_ASSERT(pin != (uint32_t)NC);
bogdanm 0:9b334a45a8ff 42
bogdanm 0:9b334a45a8ff 43 int sct_n = get_available_sct();
bogdanm 0:9b334a45a8ff 44 if (sct_n == -1) {
bogdanm 0:9b334a45a8ff 45 error("No available SCT");
bogdanm 0:9b334a45a8ff 46 }
bogdanm 0:9b334a45a8ff 47
bogdanm 0:9b334a45a8ff 48 sct_used |= (1 << sct_n);
bogdanm 0:9b334a45a8ff 49 obj->pwm = SCTs[sct_n];
bogdanm 0:9b334a45a8ff 50 obj->pwm_ch = sct_n;
bogdanm 0:9b334a45a8ff 51
bogdanm 0:9b334a45a8ff 52 LPC_SCT0_Type* pwm = obj->pwm;
bogdanm 0:9b334a45a8ff 53
bogdanm 0:9b334a45a8ff 54 // Enable the SCT clock
bogdanm 0:9b334a45a8ff 55 LPC_SYSCON->SYSAHBCLKCTRL1 |= (1 << (obj->pwm_ch + 2));
bogdanm 0:9b334a45a8ff 56
bogdanm 0:9b334a45a8ff 57 // Clear peripheral reset the SCT:
bogdanm 0:9b334a45a8ff 58 LPC_SYSCON->PRESETCTRL1 |= (1 << (obj->pwm_ch + 2));
bogdanm 0:9b334a45a8ff 59 LPC_SYSCON->PRESETCTRL1 &= ~(1 << (obj->pwm_ch + 2));
bogdanm 0:9b334a45a8ff 60
bogdanm 0:9b334a45a8ff 61 switch(obj->pwm_ch) {
bogdanm 0:9b334a45a8ff 62 case 0:
bogdanm 0:9b334a45a8ff 63 // SCT0_OUT0
bogdanm 0:9b334a45a8ff 64 LPC_SWM->PINASSIGN[7] &= ~0x0000FF00;
bogdanm 0:9b334a45a8ff 65 LPC_SWM->PINASSIGN[7] |= (pin << 8);
bogdanm 0:9b334a45a8ff 66 break;
bogdanm 0:9b334a45a8ff 67 case 1:
bogdanm 0:9b334a45a8ff 68 // SCT1_OUT0
bogdanm 0:9b334a45a8ff 69 LPC_SWM->PINASSIGN[8] &= ~0x000000FF;
bogdanm 0:9b334a45a8ff 70 LPC_SWM->PINASSIGN[8] |= (pin);
bogdanm 0:9b334a45a8ff 71 break;
bogdanm 0:9b334a45a8ff 72 case 2:
bogdanm 0:9b334a45a8ff 73 // SCT2_OUT0
bogdanm 0:9b334a45a8ff 74 LPC_SWM->PINASSIGN[8] &= ~0xFF000000;
bogdanm 0:9b334a45a8ff 75 LPC_SWM->PINASSIGN[8] |= (pin << 24);
bogdanm 0:9b334a45a8ff 76 break;
bogdanm 0:9b334a45a8ff 77 case 3:
bogdanm 0:9b334a45a8ff 78 // SCT3_OUT0
bogdanm 0:9b334a45a8ff 79 LPC_SWM->PINASSIGN[9] &= ~0x00FF0000;
bogdanm 0:9b334a45a8ff 80 LPC_SWM->PINASSIGN[9] |= (pin << 16);
bogdanm 0:9b334a45a8ff 81 break;
bogdanm 0:9b334a45a8ff 82 default:
bogdanm 0:9b334a45a8ff 83 break;
bogdanm 0:9b334a45a8ff 84 }
bogdanm 0:9b334a45a8ff 85
bogdanm 0:9b334a45a8ff 86 // Unified 32-bit counter, autolimit
bogdanm 0:9b334a45a8ff 87 pwm->CONFIG |= ((0x3 << 17) | 0x01);
bogdanm 0:9b334a45a8ff 88
bogdanm 0:9b334a45a8ff 89 // halt and clear the counter
bogdanm 0:9b334a45a8ff 90 pwm->CTRL |= (1 << 2) | (1 << 3);
bogdanm 0:9b334a45a8ff 91
bogdanm 0:9b334a45a8ff 92 // System Clock -> us_ticker (1)MHz
bogdanm 0:9b334a45a8ff 93 pwm->CTRL &= ~(0x7F << 5);
bogdanm 0:9b334a45a8ff 94 pwm->CTRL |= (((SystemCoreClock/1000000 - 1) & 0x7F) << 5);
bogdanm 0:9b334a45a8ff 95
bogdanm 0:9b334a45a8ff 96 // Match reload register
bogdanm 0:9b334a45a8ff 97 pwm->MATCHREL0 = 20000; // 20ms
bogdanm 0:9b334a45a8ff 98 pwm->MATCHREL1 = (pwm->MATCHREL0 / 4); // 50% duty
bogdanm 0:9b334a45a8ff 99
bogdanm 0:9b334a45a8ff 100 pwm->OUT0_SET = (1 << 0); // event 0
bogdanm 0:9b334a45a8ff 101 pwm->OUT0_CLR = (1 << 1); // event 1
bogdanm 0:9b334a45a8ff 102
bogdanm 0:9b334a45a8ff 103 pwm->EV0_CTRL = (1 << 12);
bogdanm 0:9b334a45a8ff 104 pwm->EV0_STATE = 0xFFFFFFFF;
bogdanm 0:9b334a45a8ff 105 pwm->EV1_CTRL = (1 << 12) | (1 << 0);
bogdanm 0:9b334a45a8ff 106 pwm->EV1_STATE = 0xFFFFFFFF;
bogdanm 0:9b334a45a8ff 107
bogdanm 0:9b334a45a8ff 108 // unhalt the counter:
bogdanm 0:9b334a45a8ff 109 // - clearing bit 2 of the CTRL register
bogdanm 0:9b334a45a8ff 110 pwm->CTRL &= ~(1 << 2);
bogdanm 0:9b334a45a8ff 111
bogdanm 0:9b334a45a8ff 112 // default to 20ms: standard for servos, and fine for e.g. brightness control
bogdanm 0:9b334a45a8ff 113 pwmout_period_ms(obj, 20);
bogdanm 0:9b334a45a8ff 114 pwmout_write (obj, 0);
bogdanm 0:9b334a45a8ff 115 }
bogdanm 0:9b334a45a8ff 116
bogdanm 0:9b334a45a8ff 117 void pwmout_free(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 118 // Disable the SCT clock
bogdanm 0:9b334a45a8ff 119 LPC_SYSCON->SYSAHBCLKCTRL1 &= ~(1 << (obj->pwm_ch + 2));
bogdanm 0:9b334a45a8ff 120 sct_used &= ~(1 << obj->pwm_ch);
bogdanm 0:9b334a45a8ff 121 }
bogdanm 0:9b334a45a8ff 122
bogdanm 0:9b334a45a8ff 123 void pwmout_write(pwmout_t* obj, float value) {
bogdanm 0:9b334a45a8ff 124 LPC_SCT0_Type* pwm = obj->pwm;
bogdanm 0:9b334a45a8ff 125 if (value < 0.0f) {
bogdanm 0:9b334a45a8ff 126 value = 0.0;
bogdanm 0:9b334a45a8ff 127 } else if (value > 1.0f) {
bogdanm 0:9b334a45a8ff 128 value = 1.0;
bogdanm 0:9b334a45a8ff 129 }
bogdanm 0:9b334a45a8ff 130 uint32_t t_on = (uint32_t)((float)(pwm->MATCHREL0) * value);
bogdanm 0:9b334a45a8ff 131 pwm->MATCHREL1 = t_on;
bogdanm 0:9b334a45a8ff 132 }
bogdanm 0:9b334a45a8ff 133
bogdanm 0:9b334a45a8ff 134 float pwmout_read(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 135 uint32_t t_off = obj->pwm->MATCHREL0;
bogdanm 0:9b334a45a8ff 136 uint32_t t_on = obj->pwm->MATCHREL1;
bogdanm 0:9b334a45a8ff 137 float v = (float)t_on/(float)t_off;
bogdanm 0:9b334a45a8ff 138 return (v > 1.0f) ? (1.0f) : (v);
bogdanm 0:9b334a45a8ff 139 }
bogdanm 0:9b334a45a8ff 140
bogdanm 0:9b334a45a8ff 141 void pwmout_period(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 142 pwmout_period_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 143 }
bogdanm 0:9b334a45a8ff 144
bogdanm 0:9b334a45a8ff 145 void pwmout_period_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 146 pwmout_period_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 147 }
bogdanm 0:9b334a45a8ff 148
bogdanm 0:9b334a45a8ff 149 // Set the PWM period, keeping the duty cycle the same.
bogdanm 0:9b334a45a8ff 150 void pwmout_period_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 151 LPC_SCT0_Type* pwm = obj->pwm;
bogdanm 0:9b334a45a8ff 152 uint32_t t_off = pwm->MATCHREL0;
bogdanm 0:9b334a45a8ff 153 uint32_t t_on = pwm->MATCHREL1;
bogdanm 0:9b334a45a8ff 154 float v = (float)t_on/(float)t_off;
bogdanm 0:9b334a45a8ff 155 pwm->MATCHREL0 = (uint32_t)us;
bogdanm 0:9b334a45a8ff 156 pwm->MATCHREL1 = (uint32_t)((float)us * (float)v);
bogdanm 0:9b334a45a8ff 157 }
bogdanm 0:9b334a45a8ff 158
bogdanm 0:9b334a45a8ff 159 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 160 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 161 }
bogdanm 0:9b334a45a8ff 162
bogdanm 0:9b334a45a8ff 163 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 164 pwmout_pulsewidth_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 165 }
bogdanm 0:9b334a45a8ff 166
bogdanm 0:9b334a45a8ff 167 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 168 obj->pwm->MATCHREL1 = (uint32_t)us;
bogdanm 0:9b334a45a8ff 169 }
bogdanm 0:9b334a45a8ff 170