EL4121 Embedded System / mbed-os

mbed-os

Dependents:   cobaLCDJoyMotor_Thread odometry_omni_3roda_v3 odometry_omni_3roda_v1 odometry_omni_3roda_v2 ... more

targets/TARGET_NXP/TARGET_LPC176X/pwmout_api.c@0:b74591d5ab33, 2017-12-11 (annotated)

Committer:
be_bryan
Date:
Mon Dec 11 17:54:04 2017 +0000
Revision:
0:b74591d5ab33
motor ++

Who changed what in which revision?

UserRevisionLine numberNew contents of line
be_bryan 0:b74591d5ab33 1 /* mbed Microcontroller Library
be_bryan 0:b74591d5ab33 2 * Copyright (c) 2006-2013 ARM Limited
be_bryan 0:b74591d5ab33 3 *
be_bryan 0:b74591d5ab33 4 * Licensed under the Apache License, Version 2.0 (the "License");
be_bryan 0:b74591d5ab33 5 * you may not use this file except in compliance with the License.
be_bryan 0:b74591d5ab33 6 * You may obtain a copy of the License at
be_bryan 0:b74591d5ab33 7 *
be_bryan 0:b74591d5ab33 8 * http://www.apache.org/licenses/LICENSE-2.0
be_bryan 0:b74591d5ab33 9 *
be_bryan 0:b74591d5ab33 10 * Unless required by applicable law or agreed to in writing, software
be_bryan 0:b74591d5ab33 11 * distributed under the License is distributed on an "AS IS" BASIS,
be_bryan 0:b74591d5ab33 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
be_bryan 0:b74591d5ab33 13 * See the License for the specific language governing permissions and
be_bryan 0:b74591d5ab33 14 * limitations under the License.
be_bryan 0:b74591d5ab33 15 */
be_bryan 0:b74591d5ab33 16 #include "mbed_assert.h"
be_bryan 0:b74591d5ab33 17 #include "pwmout_api.h"
be_bryan 0:b74591d5ab33 18 #include "cmsis.h"
be_bryan 0:b74591d5ab33 19 #include "pinmap.h"
be_bryan 0:b74591d5ab33 20
be_bryan 0:b74591d5ab33 21 #define TCR_CNT_EN 0x00000001
be_bryan 0:b74591d5ab33 22 #define TCR_RESET 0x00000002
be_bryan 0:b74591d5ab33 23
be_bryan 0:b74591d5ab33 24 // PORT ID, PWM ID, Pin function
be_bryan 0:b74591d5ab33 25 static const PinMap PinMap_PWM[] = {
be_bryan 0:b74591d5ab33 26 {P1_18, PWM_1, 2},
be_bryan 0:b74591d5ab33 27 {P1_20, PWM_2, 2},
be_bryan 0:b74591d5ab33 28 {P1_21, PWM_3, 2},
be_bryan 0:b74591d5ab33 29 {P1_23, PWM_4, 2},
be_bryan 0:b74591d5ab33 30 {P1_24, PWM_5, 2},
be_bryan 0:b74591d5ab33 31 {P1_26, PWM_6, 2},
be_bryan 0:b74591d5ab33 32 {P2_0 , PWM_1, 1},
be_bryan 0:b74591d5ab33 33 {P2_1 , PWM_2, 1},
be_bryan 0:b74591d5ab33 34 {P2_2 , PWM_3, 1},
be_bryan 0:b74591d5ab33 35 {P2_3 , PWM_4, 1},
be_bryan 0:b74591d5ab33 36 {P2_4 , PWM_5, 1},
be_bryan 0:b74591d5ab33 37 {P2_5 , PWM_6, 1},
be_bryan 0:b74591d5ab33 38 {P3_25, PWM_2, 3},
be_bryan 0:b74591d5ab33 39 {P3_26, PWM_3, 3},
be_bryan 0:b74591d5ab33 40 {NC, NC, 0}
be_bryan 0:b74591d5ab33 41 };
be_bryan 0:b74591d5ab33 42
be_bryan 0:b74591d5ab33 43 __IO uint32_t *PWM_MATCH[] = {
be_bryan 0:b74591d5ab33 44 &(LPC_PWM1->MR0),
be_bryan 0:b74591d5ab33 45 &(LPC_PWM1->MR1),
be_bryan 0:b74591d5ab33 46 &(LPC_PWM1->MR2),
be_bryan 0:b74591d5ab33 47 &(LPC_PWM1->MR3),
be_bryan 0:b74591d5ab33 48 &(LPC_PWM1->MR4),
be_bryan 0:b74591d5ab33 49 &(LPC_PWM1->MR5),
be_bryan 0:b74591d5ab33 50 &(LPC_PWM1->MR6)
be_bryan 0:b74591d5ab33 51 };
be_bryan 0:b74591d5ab33 52
be_bryan 0:b74591d5ab33 53 #define TCR_PWM_EN 0x00000008
be_bryan 0:b74591d5ab33 54
be_bryan 0:b74591d5ab33 55 static unsigned int pwm_clock_mhz;
be_bryan 0:b74591d5ab33 56
be_bryan 0:b74591d5ab33 57 void pwmout_init(pwmout_t* obj, PinName pin) {
be_bryan 0:b74591d5ab33 58 // determine the channel
be_bryan 0:b74591d5ab33 59 PWMName pwm = (PWMName)pinmap_peripheral(pin, PinMap_PWM);
be_bryan 0:b74591d5ab33 60 MBED_ASSERT(pwm != (PWMName)NC);
be_bryan 0:b74591d5ab33 61
be_bryan 0:b74591d5ab33 62 obj->pwm = pwm;
be_bryan 0:b74591d5ab33 63 obj->MR = PWM_MATCH[pwm];
be_bryan 0:b74591d5ab33 64
be_bryan 0:b74591d5ab33 65 // ensure the power is on
be_bryan 0:b74591d5ab33 66 LPC_SC->PCONP |= 1 << 6;
be_bryan 0:b74591d5ab33 67
be_bryan 0:b74591d5ab33 68 // ensure clock to /4
be_bryan 0:b74591d5ab33 69 LPC_SC->PCLKSEL0 &= ~(0x3 << 12); // pclk = /4
be_bryan 0:b74591d5ab33 70 LPC_PWM1->PR = 0; // no pre-scale
be_bryan 0:b74591d5ab33 71
be_bryan 0:b74591d5ab33 72 // ensure single PWM mode
be_bryan 0:b74591d5ab33 73 LPC_PWM1->MCR = 1 << 1; // reset TC on match 0
be_bryan 0:b74591d5ab33 74
be_bryan 0:b74591d5ab33 75 // enable the specific PWM output
be_bryan 0:b74591d5ab33 76 LPC_PWM1->PCR |= 1 << (8 + pwm);
be_bryan 0:b74591d5ab33 77
be_bryan 0:b74591d5ab33 78 pwm_clock_mhz = SystemCoreClock / 4000000;
be_bryan 0:b74591d5ab33 79
be_bryan 0:b74591d5ab33 80 // default to 20ms: standard for servos, and fine for e.g. brightness control
be_bryan 0:b74591d5ab33 81 pwmout_period_ms(obj, 20);
be_bryan 0:b74591d5ab33 82 pwmout_write (obj, 0);
be_bryan 0:b74591d5ab33 83
be_bryan 0:b74591d5ab33 84 // Wire pinout
be_bryan 0:b74591d5ab33 85 pinmap_pinout(pin, PinMap_PWM);
be_bryan 0:b74591d5ab33 86 }
be_bryan 0:b74591d5ab33 87
be_bryan 0:b74591d5ab33 88 void pwmout_free(pwmout_t* obj) {
be_bryan 0:b74591d5ab33 89 // [TODO]
be_bryan 0:b74591d5ab33 90 }
be_bryan 0:b74591d5ab33 91
be_bryan 0:b74591d5ab33 92 void pwmout_write(pwmout_t* obj, float value) {
be_bryan 0:b74591d5ab33 93 if (value < 0.0f) {
be_bryan 0:b74591d5ab33 94 value = 0.0;
be_bryan 0:b74591d5ab33 95 } else if (value > 1.0f) {
be_bryan 0:b74591d5ab33 96 value = 1.0;
be_bryan 0:b74591d5ab33 97 }
be_bryan 0:b74591d5ab33 98
be_bryan 0:b74591d5ab33 99 // set channel match to percentage
be_bryan 0:b74591d5ab33 100 uint32_t v = (uint32_t)((float)(LPC_PWM1->MR0) * value);
be_bryan 0:b74591d5ab33 101
be_bryan 0:b74591d5ab33 102 // workaround for PWM1[1] - Never make it equal MR0, else we get 1 cycle dropout
be_bryan 0:b74591d5ab33 103 if (v == LPC_PWM1->MR0) {
be_bryan 0:b74591d5ab33 104 v++;
be_bryan 0:b74591d5ab33 105 }
be_bryan 0:b74591d5ab33 106
be_bryan 0:b74591d5ab33 107 *obj->MR = v;
be_bryan 0:b74591d5ab33 108
be_bryan 0:b74591d5ab33 109 // accept on next period start
be_bryan 0:b74591d5ab33 110 LPC_PWM1->LER |= 1 << obj->pwm;
be_bryan 0:b74591d5ab33 111 }
be_bryan 0:b74591d5ab33 112
be_bryan 0:b74591d5ab33 113 float pwmout_read(pwmout_t* obj) {
be_bryan 0:b74591d5ab33 114 float v = (float)(*obj->MR) / (float)(LPC_PWM1->MR0);
be_bryan 0:b74591d5ab33 115 return (v > 1.0f) ? (1.0f) : (v);
be_bryan 0:b74591d5ab33 116 }
be_bryan 0:b74591d5ab33 117
be_bryan 0:b74591d5ab33 118 void pwmout_period(pwmout_t* obj, float seconds) {
be_bryan 0:b74591d5ab33 119 pwmout_period_us(obj, seconds * 1000000.0f);
be_bryan 0:b74591d5ab33 120 }
be_bryan 0:b74591d5ab33 121
be_bryan 0:b74591d5ab33 122 void pwmout_period_ms(pwmout_t* obj, int ms) {
be_bryan 0:b74591d5ab33 123 pwmout_period_us(obj, ms * 1000);
be_bryan 0:b74591d5ab33 124 }
be_bryan 0:b74591d5ab33 125
be_bryan 0:b74591d5ab33 126 // Set the PWM period, keeping the duty cycle the same.
be_bryan 0:b74591d5ab33 127 void pwmout_period_us(pwmout_t* obj, int us) {
be_bryan 0:b74591d5ab33 128 // calculate number of ticks
be_bryan 0:b74591d5ab33 129 uint32_t ticks = pwm_clock_mhz * us;
be_bryan 0:b74591d5ab33 130
be_bryan 0:b74591d5ab33 131 // set reset
be_bryan 0:b74591d5ab33 132 LPC_PWM1->TCR = TCR_RESET;
be_bryan 0:b74591d5ab33 133
be_bryan 0:b74591d5ab33 134 // set the global match register
be_bryan 0:b74591d5ab33 135 LPC_PWM1->MR0 = ticks;
be_bryan 0:b74591d5ab33 136
be_bryan 0:b74591d5ab33 137 // Scale the pulse width to preserve the duty ratio
be_bryan 0:b74591d5ab33 138 if (LPC_PWM1->MR0 > 0) {
be_bryan 0:b74591d5ab33 139 *obj->MR = (*obj->MR * ticks) / LPC_PWM1->MR0;
be_bryan 0:b74591d5ab33 140 }
be_bryan 0:b74591d5ab33 141
be_bryan 0:b74591d5ab33 142 // set the channel latch to update value at next period start
be_bryan 0:b74591d5ab33 143 LPC_PWM1->LER |= 1 << 0;
be_bryan 0:b74591d5ab33 144
be_bryan 0:b74591d5ab33 145 // enable counter and pwm, clear reset
be_bryan 0:b74591d5ab33 146 LPC_PWM1->TCR = TCR_CNT_EN | TCR_PWM_EN;
be_bryan 0:b74591d5ab33 147 }
be_bryan 0:b74591d5ab33 148
be_bryan 0:b74591d5ab33 149 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
be_bryan 0:b74591d5ab33 150 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
be_bryan 0:b74591d5ab33 151 }
be_bryan 0:b74591d5ab33 152
be_bryan 0:b74591d5ab33 153 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms) {
be_bryan 0:b74591d5ab33 154 pwmout_pulsewidth_us(obj, ms * 1000);
be_bryan 0:b74591d5ab33 155 }
be_bryan 0:b74591d5ab33 156
be_bryan 0:b74591d5ab33 157 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
be_bryan 0:b74591d5ab33 158 // calculate number of ticks
be_bryan 0:b74591d5ab33 159 uint32_t v = pwm_clock_mhz * us;
be_bryan 0:b74591d5ab33 160
be_bryan 0:b74591d5ab33 161 // workaround for PWM1[1] - Never make it equal MR0, else we get 1 cycle dropout
be_bryan 0:b74591d5ab33 162 if (v == LPC_PWM1->MR0) {
be_bryan 0:b74591d5ab33 163 v++;
be_bryan 0:b74591d5ab33 164 }
be_bryan 0:b74591d5ab33 165
be_bryan 0:b74591d5ab33 166 // set the match register value
be_bryan 0:b74591d5ab33 167 *obj->MR = v;
be_bryan 0:b74591d5ab33 168
be_bryan 0:b74591d5ab33 169 // set the channel latch to update value at next period start
be_bryan 0:b74591d5ab33 170 LPC_PWM1->LER |= 1 << obj->pwm;
be_bryan 0:b74591d5ab33 171 }