siva surendar / mbed-dev

mbed library sources. Supersedes mbed-src.

Fork of mbed-dev by mbed official

targets/TARGET_NXP/TARGET_LPC176X/pwmout_api.c@150:da61ba4e9755, 2016-11-25 (annotated)

Committer:
sivasuren
Date:
Fri Nov 25 07:57:40 2016 +0000
Revision:
150:da61ba4e9755
Parent:
149:156823d33999 
surendar changes

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /* mbed Microcontroller Library
<> 144:ef7eb2e8f9f7 2 * Copyright (c) 2006-2013 ARM Limited
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Licensed under the Apache License, Version 2.0 (the "License");
<> 144:ef7eb2e8f9f7 5 * you may not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 6 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 11 * distributed under the License is distributed on an "AS IS" BASIS,
<> 144:ef7eb2e8f9f7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 13 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 14 * limitations under the License.
<> 144:ef7eb2e8f9f7 15 */
<> 144:ef7eb2e8f9f7 16 #include "mbed_assert.h"
<> 144:ef7eb2e8f9f7 17 #include "pwmout_api.h"
<> 144:ef7eb2e8f9f7 18 #include "cmsis.h"
<> 144:ef7eb2e8f9f7 19 #include "pinmap.h"
<> 144:ef7eb2e8f9f7 20
<> 144:ef7eb2e8f9f7 21 #define TCR_CNT_EN 0x00000001
<> 144:ef7eb2e8f9f7 22 #define TCR_RESET 0x00000002
<> 144:ef7eb2e8f9f7 23
<> 144:ef7eb2e8f9f7 24 // PORT ID, PWM ID, Pin function
<> 144:ef7eb2e8f9f7 25 static const PinMap PinMap_PWM[] = {
<> 144:ef7eb2e8f9f7 26 {P1_18, PWM_1, 2},
<> 144:ef7eb2e8f9f7 27 {P1_20, PWM_2, 2},
<> 144:ef7eb2e8f9f7 28 {P1_21, PWM_3, 2},
<> 144:ef7eb2e8f9f7 29 {P1_23, PWM_4, 2},
<> 144:ef7eb2e8f9f7 30 {P1_24, PWM_5, 2},
<> 144:ef7eb2e8f9f7 31 {P1_26, PWM_6, 2},
<> 144:ef7eb2e8f9f7 32 {P2_0 , PWM_1, 1},
<> 144:ef7eb2e8f9f7 33 {P2_1 , PWM_2, 1},
<> 144:ef7eb2e8f9f7 34 {P2_2 , PWM_3, 1},
<> 144:ef7eb2e8f9f7 35 {P2_3 , PWM_4, 1},
<> 144:ef7eb2e8f9f7 36 {P2_4 , PWM_5, 1},
<> 144:ef7eb2e8f9f7 37 {P2_5 , PWM_6, 1},
<> 144:ef7eb2e8f9f7 38 {P3_25, PWM_2, 3},
<> 144:ef7eb2e8f9f7 39 {P3_26, PWM_3, 3},
<> 144:ef7eb2e8f9f7 40 {NC, NC, 0}
<> 144:ef7eb2e8f9f7 41 };
<> 144:ef7eb2e8f9f7 42
<> 144:ef7eb2e8f9f7 43 __IO uint32_t *PWM_MATCH[] = {
<> 144:ef7eb2e8f9f7 44 &(LPC_PWM1->MR0),
<> 144:ef7eb2e8f9f7 45 &(LPC_PWM1->MR1),
<> 144:ef7eb2e8f9f7 46 &(LPC_PWM1->MR2),
<> 144:ef7eb2e8f9f7 47 &(LPC_PWM1->MR3),
<> 144:ef7eb2e8f9f7 48 &(LPC_PWM1->MR4),
<> 144:ef7eb2e8f9f7 49 &(LPC_PWM1->MR5),
<> 144:ef7eb2e8f9f7 50 &(LPC_PWM1->MR6)
<> 144:ef7eb2e8f9f7 51 };
<> 144:ef7eb2e8f9f7 52
<> 144:ef7eb2e8f9f7 53 #define TCR_PWM_EN 0x00000008
<> 144:ef7eb2e8f9f7 54
<> 144:ef7eb2e8f9f7 55 static unsigned int pwm_clock_mhz;
<> 144:ef7eb2e8f9f7 56
<> 144:ef7eb2e8f9f7 57 void pwmout_init(pwmout_t* obj, PinName pin) {
<> 144:ef7eb2e8f9f7 58 // determine the channel
<> 144:ef7eb2e8f9f7 59 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
<> 144:ef7eb2e8f9f7 60 MBED_ASSERT(pwm != (PWMName)NC);
<> 144:ef7eb2e8f9f7 61
<> 144:ef7eb2e8f9f7 62 obj->pwm = pwm;
<> 144:ef7eb2e8f9f7 63 obj->MR = PWM_MATCH[pwm];
<> 144:ef7eb2e8f9f7 64
<> 144:ef7eb2e8f9f7 65 // ensure the power is on
<> 144:ef7eb2e8f9f7 66 LPC_SC->PCONP |= 1 << 6;
<> 144:ef7eb2e8f9f7 67
<> 144:ef7eb2e8f9f7 68 // ensure clock to /4
<> 144:ef7eb2e8f9f7 69 LPC_SC->PCLKSEL0 &= ~(0x3 << 12); // pclk = /4
<> 144:ef7eb2e8f9f7 70 LPC_PWM1->PR = 0; // no pre-scale
<> 144:ef7eb2e8f9f7 71
<> 144:ef7eb2e8f9f7 72 // ensure single PWM mode
<> 144:ef7eb2e8f9f7 73 LPC_PWM1->MCR = 1 << 1; // reset TC on match 0
<> 144:ef7eb2e8f9f7 74
<> 144:ef7eb2e8f9f7 75 // enable the specific PWM output
<> 144:ef7eb2e8f9f7 76 LPC_PWM1->PCR |= 1 << (8 + pwm);
<> 144:ef7eb2e8f9f7 77
<> 144:ef7eb2e8f9f7 78 pwm_clock_mhz = SystemCoreClock / 4000000;
<> 144:ef7eb2e8f9f7 79
<> 144:ef7eb2e8f9f7 80 // default to 20ms: standard for servos, and fine for e.g. brightness control
<> 144:ef7eb2e8f9f7 81 pwmout_period_ms(obj, 20);
<> 144:ef7eb2e8f9f7 82 pwmout_write (obj, 0);
<> 144:ef7eb2e8f9f7 83
<> 144:ef7eb2e8f9f7 84 // Wire pinout
<> 144:ef7eb2e8f9f7 85 pinmap_pinout(pin, PinMap_PWM);
<> 144:ef7eb2e8f9f7 86 }
<> 144:ef7eb2e8f9f7 87
<> 144:ef7eb2e8f9f7 88 void pwmout_free(pwmout_t* obj) {
<> 144:ef7eb2e8f9f7 89 // [TODO]
<> 144:ef7eb2e8f9f7 90 }
<> 144:ef7eb2e8f9f7 91
<> 144:ef7eb2e8f9f7 92 void pwmout_write(pwmout_t* obj, float value) {
<> 144:ef7eb2e8f9f7 93 if (value < 0.0f) {
<> 144:ef7eb2e8f9f7 94 value = 0.0;
<> 144:ef7eb2e8f9f7 95 } else if (value > 1.0f) {
<> 144:ef7eb2e8f9f7 96 value = 1.0;
<> 144:ef7eb2e8f9f7 97 }
<> 144:ef7eb2e8f9f7 98
<> 144:ef7eb2e8f9f7 99 // set channel match to percentage
<> 144:ef7eb2e8f9f7 100 uint32_t v = (uint32_t)((float)(LPC_PWM1->MR0) * value);
<> 144:ef7eb2e8f9f7 101
<> 144:ef7eb2e8f9f7 102 // workaround for PWM1[1] - Never make it equal MR0, else we get 1 cycle dropout
<> 144:ef7eb2e8f9f7 103 if (v == LPC_PWM1->MR0) {
<> 144:ef7eb2e8f9f7 104 v++;
<> 144:ef7eb2e8f9f7 105 }
<> 144:ef7eb2e8f9f7 106
<> 144:ef7eb2e8f9f7 107 *obj->MR = v;
<> 144:ef7eb2e8f9f7 108
<> 144:ef7eb2e8f9f7 109 // accept on next period start
<> 144:ef7eb2e8f9f7 110 LPC_PWM1->LER |= 1 << obj->pwm;
<> 144:ef7eb2e8f9f7 111 }
<> 144:ef7eb2e8f9f7 112
<> 144:ef7eb2e8f9f7 113 float pwmout_read(pwmout_t* obj) {
<> 144:ef7eb2e8f9f7 114 float v = (float)(*obj->MR) / (float)(LPC_PWM1->MR0);
<> 144:ef7eb2e8f9f7 115 return (v > 1.0f) ? (1.0f) : (v);
<> 144:ef7eb2e8f9f7 116 }
<> 144:ef7eb2e8f9f7 117
<> 144:ef7eb2e8f9f7 118 void pwmout_period(pwmout_t* obj, float seconds) {
<> 144:ef7eb2e8f9f7 119 pwmout_period_us(obj, seconds * 1000000.0f);
<> 144:ef7eb2e8f9f7 120 }
<> 144:ef7eb2e8f9f7 121
<> 144:ef7eb2e8f9f7 122 void pwmout_period_ms(pwmout_t* obj, int ms) {
<> 144:ef7eb2e8f9f7 123 pwmout_period_us(obj, ms * 1000);
<> 144:ef7eb2e8f9f7 124 }
<> 144:ef7eb2e8f9f7 125
<> 144:ef7eb2e8f9f7 126 // Set the PWM period, keeping the duty cycle the same.
<> 144:ef7eb2e8f9f7 127 void pwmout_period_us(pwmout_t* obj, int us) {
<> 144:ef7eb2e8f9f7 128 // calculate number of ticks
<> 144:ef7eb2e8f9f7 129 uint32_t ticks = pwm_clock_mhz * us;
<> 144:ef7eb2e8f9f7 130
<> 144:ef7eb2e8f9f7 131 // set reset
<> 144:ef7eb2e8f9f7 132 LPC_PWM1->TCR = TCR_RESET;
<> 144:ef7eb2e8f9f7 133
<> 144:ef7eb2e8f9f7 134 // set the global match register
<> 144:ef7eb2e8f9f7 135 LPC_PWM1->MR0 = ticks;
<> 144:ef7eb2e8f9f7 136
<> 144:ef7eb2e8f9f7 137 // Scale the pulse width to preserve the duty ratio
<> 144:ef7eb2e8f9f7 138 if (LPC_PWM1->MR0 > 0) {
<> 144:ef7eb2e8f9f7 139 *obj->MR = (*obj->MR * ticks) / LPC_PWM1->MR0;
<> 144:ef7eb2e8f9f7 140 }
<> 144:ef7eb2e8f9f7 141
<> 144:ef7eb2e8f9f7 142 // set the channel latch to update value at next period start
<> 144:ef7eb2e8f9f7 143 LPC_PWM1->LER |= 1 << 0;
<> 144:ef7eb2e8f9f7 144
<> 144:ef7eb2e8f9f7 145 // enable counter and pwm, clear reset
<> 144:ef7eb2e8f9f7 146 LPC_PWM1->TCR = TCR_CNT_EN | TCR_PWM_EN;
<> 144:ef7eb2e8f9f7 147 }
<> 144:ef7eb2e8f9f7 148
<> 144:ef7eb2e8f9f7 149 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
<> 144:ef7eb2e8f9f7 150 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
<> 144:ef7eb2e8f9f7 151 }
<> 144:ef7eb2e8f9f7 152
<> 144:ef7eb2e8f9f7 153 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
<> 144:ef7eb2e8f9f7 154 pwmout_pulsewidth_us(obj, ms * 1000);
<> 144:ef7eb2e8f9f7 155 }
<> 144:ef7eb2e8f9f7 156
<> 144:ef7eb2e8f9f7 157 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
<> 144:ef7eb2e8f9f7 158 // calculate number of ticks
<> 144:ef7eb2e8f9f7 159 uint32_t v = pwm_clock_mhz * us;
<> 144:ef7eb2e8f9f7 160
<> 144:ef7eb2e8f9f7 161 // workaround for PWM1[1] - Never make it equal MR0, else we get 1 cycle dropout
<> 144:ef7eb2e8f9f7 162 if (v == LPC_PWM1->MR0) {
<> 144:ef7eb2e8f9f7 163 v++;
<> 144:ef7eb2e8f9f7 164 }
<> 144:ef7eb2e8f9f7 165
<> 144:ef7eb2e8f9f7 166 // set the match register value
<> 144:ef7eb2e8f9f7 167 *obj->MR = v;
<> 144:ef7eb2e8f9f7 168
<> 144:ef7eb2e8f9f7 169 // set the channel latch to update value at next period start
<> 144:ef7eb2e8f9f7 170 LPC_PWM1->LER |= 1 << obj->pwm;
<> 144:ef7eb2e8f9f7 171 }