en 129 / mbed-dev

fix LPC812 PWM

Dependents:   IR_LED_Send

Fork of mbed-dev by mbed official

targets/hal/TARGET_NXP/TARGET_LPC81X/pwmout_api.c@129:2e517c56bcfb, 2016-05-16 (annotated)

Committer:
nameless129
Date:
Mon May 16 16:50:30 2016 +0000
Revision:
129:2e517c56bcfb
Parent:
108:e46d5651bd87 
PWM Fix:Duty 0%??H???????????????

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 // Ported from LPC824 and adapted.
bogdanm 0:9b334a45a8ff 23
bogdanm 0:9b334a45a8ff 24 #if DEVICE_PWMOUT
bogdanm 0:9b334a45a8ff 25
bogdanm 0:9b334a45a8ff 26 #define PWM_IRQn SCT_IRQn
bogdanm 0:9b334a45a8ff 27
bogdanm 0:9b334a45a8ff 28 // Bit flags for used SCT Outputs
bogdanm 0:9b334a45a8ff 29 static unsigned char sct_used = 0;
bogdanm 0:9b334a45a8ff 30 static int sct_inited = 0;
bogdanm 0:9b334a45a8ff 31
bogdanm 0:9b334a45a8ff 32 // Find available output channel
bogdanm 0:9b334a45a8ff 33 // Max number of PWM outputs is 4 on LPC812
bogdanm 0:9b334a45a8ff 34 static int get_available_sct() {
bogdanm 0:9b334a45a8ff 35 int i;
bogdanm 0:9b334a45a8ff 36
bogdanm 0:9b334a45a8ff 37 // Find available output channel 0..3
bogdanm 0:9b334a45a8ff 38 // Also need one Match register per channel
bogdanm 0:9b334a45a8ff 39 for (i = 0; i < CONFIG_SCT_nOU; i++) {
bogdanm 0:9b334a45a8ff 40 if ((sct_used & (1 << i)) == 0)
bogdanm 0:9b334a45a8ff 41 return i;
bogdanm 0:9b334a45a8ff 42 }
bogdanm 0:9b334a45a8ff 43 return -1;
bogdanm 0:9b334a45a8ff 44 }
bogdanm 0:9b334a45a8ff 45
bogdanm 0:9b334a45a8ff 46 // Any Port pin may be used for PWM.
bogdanm 0:9b334a45a8ff 47 // Max number of PWM outputs is 4
bogdanm 0:9b334a45a8ff 48 void pwmout_init(pwmout_t* obj, PinName pin) {
mbed_official 108:e46d5651bd87 49 MBED_ASSERT(pin != (PinName)NC);
bogdanm 0:9b334a45a8ff 50
bogdanm 0:9b334a45a8ff 51 int sct_n = get_available_sct();
bogdanm 0:9b334a45a8ff 52 if (sct_n == -1) {
bogdanm 0:9b334a45a8ff 53 error("No available SCT Output");
bogdanm 0:9b334a45a8ff 54 }
bogdanm 0:9b334a45a8ff 55
bogdanm 0:9b334a45a8ff 56 sct_used |= (1 << sct_n);
bogdanm 0:9b334a45a8ff 57
bogdanm 0:9b334a45a8ff 58 obj->pwm = (LPC_SCT_TypeDef*)LPC_SCT;
bogdanm 0:9b334a45a8ff 59 obj->pwm_ch = sct_n;
bogdanm 0:9b334a45a8ff 60
bogdanm 0:9b334a45a8ff 61 LPC_SCT_TypeDef* pwm = obj->pwm;
bogdanm 0:9b334a45a8ff 62
bogdanm 0:9b334a45a8ff 63 // Init SCT on first use
bogdanm 0:9b334a45a8ff 64 if (! sct_inited) {
bogdanm 0:9b334a45a8ff 65 sct_inited = 1;
bogdanm 0:9b334a45a8ff 66
bogdanm 0:9b334a45a8ff 67 // Enable the SCT clock
bogdanm 0:9b334a45a8ff 68 LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 8);
bogdanm 0:9b334a45a8ff 69
bogdanm 0:9b334a45a8ff 70 // Clear peripheral reset the SCT:
bogdanm 0:9b334a45a8ff 71 LPC_SYSCON->PRESETCTRL |= (1 << 8);
bogdanm 0:9b334a45a8ff 72
bogdanm 0:9b334a45a8ff 73 // Two 16-bit counters, autolimit (ie reset on Match_0)
bogdanm 0:9b334a45a8ff 74 pwm->CONFIG |= ((0x3 << 17) | 0x01);
bogdanm 0:9b334a45a8ff 75
bogdanm 0:9b334a45a8ff 76 // halt and clear the counter
bogdanm 0:9b334a45a8ff 77 pwm->CTRL_U |= (1 << 2) | (1 << 3);
bogdanm 0:9b334a45a8ff 78
bogdanm 0:9b334a45a8ff 79 // System Clock (30 Mhz) -> Prescaler -> us_ticker (1 MHz)
bogdanm 0:9b334a45a8ff 80 pwm->CTRL_U &= ~(0x7F << 5);
bogdanm 0:9b334a45a8ff 81 pwm->CTRL_U |= (((SystemCoreClock/1000000 - 1) & 0x7F) << 5);
bogdanm 0:9b334a45a8ff 82
bogdanm 0:9b334a45a8ff 83 pwm->EVENT[0].CTRL = (1 << 12) | 0; // Event_0 on Match_0
bogdanm 0:9b334a45a8ff 84 pwm->EVENT[0].STATE = 0xFFFFFFFF; // All states
bogdanm 0:9b334a45a8ff 85
bogdanm 0:9b334a45a8ff 86 // unhalt the counter:
bogdanm 0:9b334a45a8ff 87 // - clearing bit 2 of the CTRL register
bogdanm 0:9b334a45a8ff 88 pwm->CTRL_U &= ~(1 << 2);
bogdanm 0:9b334a45a8ff 89
bogdanm 0:9b334a45a8ff 90 }
bogdanm 0:9b334a45a8ff 91
bogdanm 0:9b334a45a8ff 92 // LPC81x has only one SCT and 4 Outputs
bogdanm 0:9b334a45a8ff 93 // LPC82x has only one SCT and 6 Outputs
bogdanm 0:9b334a45a8ff 94 // LPC1549 has 4 SCTs and 16 Outputs
bogdanm 0:9b334a45a8ff 95 switch(sct_n) {
bogdanm 0:9b334a45a8ff 96 case 0:
bogdanm 0:9b334a45a8ff 97 // SCTx_OUT0
bogdanm 0:9b334a45a8ff 98 LPC_SWM->PINASSIGN[6] &= ~0xFF000000;
bogdanm 0:9b334a45a8ff 99 LPC_SWM->PINASSIGN[6] |= (pin << 24);
bogdanm 0:9b334a45a8ff 100 break;
bogdanm 0:9b334a45a8ff 101 case 1:
bogdanm 0:9b334a45a8ff 102 // SCTx_OUT1
bogdanm 0:9b334a45a8ff 103 LPC_SWM->PINASSIGN[7] &= ~0x000000FF;
bogdanm 0:9b334a45a8ff 104 LPC_SWM->PINASSIGN[7] |= (pin);
bogdanm 0:9b334a45a8ff 105 break;
bogdanm 0:9b334a45a8ff 106 case 2:
bogdanm 0:9b334a45a8ff 107 // SCTx_OUT2
bogdanm 0:9b334a45a8ff 108 LPC_SWM->PINASSIGN[7] &= ~0x0000FF00;
bogdanm 0:9b334a45a8ff 109 LPC_SWM->PINASSIGN[7] |= (pin << 8);
bogdanm 0:9b334a45a8ff 110 break;
bogdanm 0:9b334a45a8ff 111 case 3:
bogdanm 0:9b334a45a8ff 112 // SCTx_OUT3
bogdanm 0:9b334a45a8ff 113 LPC_SWM->PINASSIGN[7] &= ~0x00FF0000;
bogdanm 0:9b334a45a8ff 114 LPC_SWM->PINASSIGN[7] |= (pin << 16);
bogdanm 0:9b334a45a8ff 115 break;
bogdanm 0:9b334a45a8ff 116 default:
bogdanm 0:9b334a45a8ff 117 break;
bogdanm 0:9b334a45a8ff 118 }
bogdanm 0:9b334a45a8ff 119
bogdanm 0:9b334a45a8ff 120 pwm->EVENT[sct_n + 1].CTRL = (1 << 12) | (sct_n + 1); // Event_n on Match_n
bogdanm 0:9b334a45a8ff 121 pwm->EVENT[sct_n + 1].STATE = 0xFFFFFFFF; // All states
bogdanm 0:9b334a45a8ff 122
bogdanm 0:9b334a45a8ff 123 pwm->OUT[sct_n].SET = (1 << 0); // All PWM channels are SET on Event_0
bogdanm 0:9b334a45a8ff 124 pwm->OUT[sct_n].CLR = (1 << (sct_n + 1)); // PWM ch is CLRed on Event_(ch+1)
nameless129 129:2e517c56bcfb 125 pwm->RES = 0x02;
nameless129 129:2e517c56bcfb 126
bogdanm 0:9b334a45a8ff 127 // default to 20ms: standard for servos, and fine for e.g. brightness control
bogdanm 0:9b334a45a8ff 128 pwmout_period_ms(obj, 20); // 20ms period
bogdanm 0:9b334a45a8ff 129 pwmout_write (obj, 0.0); // 0ms pulsewidth, dutycycle 0
bogdanm 0:9b334a45a8ff 130 }
bogdanm 0:9b334a45a8ff 131
bogdanm 0:9b334a45a8ff 132 void pwmout_free(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 133 // PWM channel is now free
bogdanm 0:9b334a45a8ff 134 sct_used &= ~(1 << obj->pwm_ch);
bogdanm 0:9b334a45a8ff 135
bogdanm 0:9b334a45a8ff 136 // Disable the SCT clock when all channels free
bogdanm 0:9b334a45a8ff 137 if (sct_used == 0) {
bogdanm 0:9b334a45a8ff 138 LPC_SYSCON->SYSAHBCLKCTRL &= ~(1 << 8);
bogdanm 0:9b334a45a8ff 139 sct_inited = 0;
bogdanm 0:9b334a45a8ff 140 };
bogdanm 0:9b334a45a8ff 141 }
bogdanm 0:9b334a45a8ff 142
bogdanm 0:9b334a45a8ff 143 // Set new dutycycle (0.0 .. 1.0)
bogdanm 0:9b334a45a8ff 144 void pwmout_write(pwmout_t* obj, float value) {
bogdanm 0:9b334a45a8ff 145 //value is new dutycycle
bogdanm 0:9b334a45a8ff 146 if (value < 0.0f) {
bogdanm 0:9b334a45a8ff 147 value = 0.0;
bogdanm 0:9b334a45a8ff 148 } else if (value > 1.0f) {
bogdanm 0:9b334a45a8ff 149 value = 1.0;
bogdanm 0:9b334a45a8ff 150 }
bogdanm 0:9b334a45a8ff 151
bogdanm 0:9b334a45a8ff 152 // Match_0 is PWM period. Compute new endtime of pulse for current channel
bogdanm 0:9b334a45a8ff 153 uint32_t t_off = (uint32_t)((float)(obj->pwm->MATCHREL[0].U) * value);
bogdanm 0:9b334a45a8ff 154 obj->pwm->MATCHREL[(obj->pwm_ch) + 1].U = t_off; // New endtime
mbed_official 108:e46d5651bd87 155
mbed_official 108:e46d5651bd87 156 if (value == 0.0f) { // duty is 0%
mbed_official 108:e46d5651bd87 157 // Set CLR event to be same as SET event, makes output to be 0 (low)
mbed_official 108:e46d5651bd87 158 obj->pwm->OUT[(obj->pwm_ch)].CLR = (1 << 0);
mbed_official 108:e46d5651bd87 159 } else {
mbed_official 108:e46d5651bd87 160 // Use normal CLR event (current SCT ch + 1)
mbed_official 108:e46d5651bd87 161 obj->pwm->OUT[(obj->pwm_ch)].CLR = (1 << ((obj->pwm_ch) + 1));
mbed_official 108:e46d5651bd87 162 }
bogdanm 0:9b334a45a8ff 163 }
bogdanm 0:9b334a45a8ff 164
bogdanm 0:9b334a45a8ff 165 // Get dutycycle (0.0 .. 1.0)
bogdanm 0:9b334a45a8ff 166 float pwmout_read(pwmout_t* obj) {
bogdanm 0:9b334a45a8ff 167 uint32_t t_period = obj->pwm->MATCHREL[0].U;
bogdanm 0:9b334a45a8ff 168
bogdanm 0:9b334a45a8ff 169 //Sanity check
bogdanm 0:9b334a45a8ff 170 if (t_period == 0) {
bogdanm 0:9b334a45a8ff 171 return 0.0;
bogdanm 0:9b334a45a8ff 172 };
bogdanm 0:9b334a45a8ff 173
bogdanm 0:9b334a45a8ff 174 uint32_t t_off = obj->pwm->MATCHREL[(obj->pwm_ch) + 1].U;
bogdanm 0:9b334a45a8ff 175 float v = (float)t_off/(float)t_period;
bogdanm 0:9b334a45a8ff 176 //Sanity check
bogdanm 0:9b334a45a8ff 177 return (v > 1.0f) ? (1.0f) : (v);
bogdanm 0:9b334a45a8ff 178 }
bogdanm 0:9b334a45a8ff 179
bogdanm 0:9b334a45a8ff 180 // Set the PWM period, keeping the duty cycle the same (for this channel only!).
bogdanm 0:9b334a45a8ff 181 void pwmout_period(pwmout_t* obj, float seconds){
bogdanm 0:9b334a45a8ff 182 pwmout_period_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 183 }
bogdanm 0:9b334a45a8ff 184
bogdanm 0:9b334a45a8ff 185 // Set the PWM period, keeping the duty cycle the same (for this channel only!).
bogdanm 0:9b334a45a8ff 186 void pwmout_period_ms(pwmout_t* obj, int ms) {
bogdanm 0:9b334a45a8ff 187 pwmout_period_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 188 }
bogdanm 0:9b334a45a8ff 189
bogdanm 0:9b334a45a8ff 190 // Set the PWM period, keeping the duty cycle the same (for this channel only!).
bogdanm 0:9b334a45a8ff 191 void pwmout_period_us(pwmout_t* obj, int us) {
bogdanm 0:9b334a45a8ff 192
bogdanm 0:9b334a45a8ff 193 uint32_t t_period = obj->pwm->MATCHREL[0].U; // Current PWM period
bogdanm 0:9b334a45a8ff 194 obj->pwm->MATCHREL[0].U = (uint32_t)us; // New PWM period
bogdanm 0:9b334a45a8ff 195
mbed_official 108:e46d5651bd87 196 // Sanity check
bogdanm 0:9b334a45a8ff 197 if (t_period == 0) {
mbed_official 108:e46d5651bd87 198 return;
bogdanm 0:9b334a45a8ff 199 }
mbed_official 108:e46d5651bd87 200 else {
mbed_official 108:e46d5651bd87 201 int cnt = sct_used;
mbed_official 108:e46d5651bd87 202 int ch = 0;
mbed_official 108:e46d5651bd87 203 // Update match period for exising PWM channels
mbed_official 108:e46d5651bd87 204 do {
mbed_official 108:e46d5651bd87 205 // Get current pulse width
mbed_official 108:e46d5651bd87 206 uint32_t t_off = obj->pwm->MATCHREL[ch + 1].U;
mbed_official 108:e46d5651bd87 207 // Get the duty
mbed_official 108:e46d5651bd87 208 float v = (float)t_off/(float)t_period;
mbed_official 108:e46d5651bd87 209 // Update pulse width for this channel
mbed_official 108:e46d5651bd87 210 obj->pwm->MATCHREL[ch + 1].U = (uint32_t)((float)us * (float)v);
mbed_official 108:e46d5651bd87 211 // Get next used SCT channel
mbed_official 108:e46d5651bd87 212 cnt = cnt >> 1;
mbed_official 108:e46d5651bd87 213 ch++;
mbed_official 108:e46d5651bd87 214 } while (cnt != 0);
mbed_official 108:e46d5651bd87 215 }
bogdanm 0:9b334a45a8ff 216 }
bogdanm 0:9b334a45a8ff 217
bogdanm 0:9b334a45a8ff 218
bogdanm 0:9b334a45a8ff 219 //Set pulsewidth
bogdanm 0:9b334a45a8ff 220 void pwmout_pulsewidth(pwmout_t* obj, float seconds) {
bogdanm 0:9b334a45a8ff 221 pwmout_pulsewidth_us(obj, seconds * 1000000.0f);
bogdanm 0:9b334a45a8ff 222 }
bogdanm 0:9b334a45a8ff 223
bogdanm 0:9b334a45a8ff 224 //Set pulsewidth
bogdanm 0:9b334a45a8ff 225 void pwmout_pulsewidth_ms(pwmout_t* obj, int ms){
bogdanm 0:9b334a45a8ff 226 pwmout_pulsewidth_us(obj, ms * 1000);
bogdanm 0:9b334a45a8ff 227 }
bogdanm 0:9b334a45a8ff 228
bogdanm 0:9b334a45a8ff 229 //Set pulsewidth
bogdanm 0:9b334a45a8ff 230 void pwmout_pulsewidth_us(pwmout_t* obj, int us) {
mbed_official 108:e46d5651bd87 231 if (us == 0) { // pulse width is 0
mbed_official 108:e46d5651bd87 232 // Set CLR event to be same as SET event, makes output to be 0 (low)
mbed_official 108:e46d5651bd87 233 obj->pwm->OUT[(obj->pwm_ch)].CLR = (1 << 0);
mbed_official 108:e46d5651bd87 234 } else {
mbed_official 108:e46d5651bd87 235 // Use normal CLR event (current SCT ch + 1)
mbed_official 108:e46d5651bd87 236 obj->pwm->OUT[(obj->pwm_ch)].CLR = (1 << ((obj->pwm_ch) + 1));
mbed_official 108:e46d5651bd87 237 }
bogdanm 0:9b334a45a8ff 238 //Should add Sanity check to make sure pulsewidth < period!
bogdanm 0:9b334a45a8ff 239 obj->pwm->MATCHREL[(obj->pwm_ch) + 1].U = (uint32_t)us; // New endtime for this channel
bogdanm 0:9b334a45a8ff 240 }
bogdanm 0:9b334a45a8ff 241
bogdanm 0:9b334a45a8ff 242 #endif