Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Maxim/TARGET_MAX32610/us_ticker.c@147:ba84b7dc41a7, 2016-09-10 (annotated)

Committer:
JojoS
Date:
Sat Sep 10 15:32:04 2016 +0000
Revision:
147:ba84b7dc41a7
Parent:
144:ef7eb2e8f9f7 
added prescaler for 16 bit timers (solution as in LPC11xx), default prescaler 31 for max 28 ms period time

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /*******************************************************************************
<> 144:ef7eb2e8f9f7 2 * Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved.
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Permission is hereby granted, free of charge, to any person obtaining a
<> 144:ef7eb2e8f9f7 5 * copy of this software and associated documentation files (the "Software"),
<> 144:ef7eb2e8f9f7 6 * to deal in the Software without restriction, including without limitation
<> 144:ef7eb2e8f9f7 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
<> 144:ef7eb2e8f9f7 8 * and/or sell copies of the Software, and to permit persons to whom the
<> 144:ef7eb2e8f9f7 9 * Software is furnished to do so, subject to the following conditions:
<> 144:ef7eb2e8f9f7 10 *
<> 144:ef7eb2e8f9f7 11 * The above copyright notice and this permission notice shall be included
<> 144:ef7eb2e8f9f7 12 * in all copies or substantial portions of the Software.
<> 144:ef7eb2e8f9f7 13 *
<> 144:ef7eb2e8f9f7 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
<> 144:ef7eb2e8f9f7 15 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
<> 144:ef7eb2e8f9f7 16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
<> 144:ef7eb2e8f9f7 17 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
<> 144:ef7eb2e8f9f7 18 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
<> 144:ef7eb2e8f9f7 19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
<> 144:ef7eb2e8f9f7 20 * OTHER DEALINGS IN THE SOFTWARE.
<> 144:ef7eb2e8f9f7 21 *
<> 144:ef7eb2e8f9f7 22 * Except as contained in this notice, the name of Maxim Integrated
<> 144:ef7eb2e8f9f7 23 * Products, Inc. shall not be used except as stated in the Maxim Integrated
<> 144:ef7eb2e8f9f7 24 * Products, Inc. Branding Policy.
<> 144:ef7eb2e8f9f7 25 *
<> 144:ef7eb2e8f9f7 26 * The mere transfer of this software does not imply any licenses
<> 144:ef7eb2e8f9f7 27 * of trade secrets, proprietary technology, copyrights, patents,
<> 144:ef7eb2e8f9f7 28 * trademarks, maskwork rights, or any other form of intellectual
<> 144:ef7eb2e8f9f7 29 * property whatsoever. Maxim Integrated Products, Inc. retains all
<> 144:ef7eb2e8f9f7 30 * ownership rights.
<> 144:ef7eb2e8f9f7 31 *******************************************************************************
<> 144:ef7eb2e8f9f7 32 */
<> 144:ef7eb2e8f9f7 33
<> 144:ef7eb2e8f9f7 34 #include "mbed_error.h"
<> 144:ef7eb2e8f9f7 35 #include "us_ticker_api.h"
<> 144:ef7eb2e8f9f7 36 #include "PeripheralNames.h"
<> 144:ef7eb2e8f9f7 37 #include "tmr_regs.h"
<> 144:ef7eb2e8f9f7 38
<> 144:ef7eb2e8f9f7 39 #define US_TIMER MXC_TMR0
<> 144:ef7eb2e8f9f7 40 #define US_TIMER_IRQn TMR0_IRQn
<> 144:ef7eb2e8f9f7 41
<> 144:ef7eb2e8f9f7 42 static int us_ticker_inited = 0;
<> 144:ef7eb2e8f9f7 43 static uint32_t ticks_per_us;
<> 144:ef7eb2e8f9f7 44 static uint32_t tick_win;
<> 144:ef7eb2e8f9f7 45 static volatile uint64_t current_cnt; // Hold the current ticks
<> 144:ef7eb2e8f9f7 46 static volatile uint64_t event_cnt; // Holds the value of the next event
<> 144:ef7eb2e8f9f7 47
<> 144:ef7eb2e8f9f7 48 #define ticks_to_us(ticks) ((ticks) / ticks_per_us);
<> 144:ef7eb2e8f9f7 49 #define MAX_TICK_VAL ((uint64_t)0xFFFFFFFF * ticks_per_us)
<> 144:ef7eb2e8f9f7 50
<> 144:ef7eb2e8f9f7 51 //******************************************************************************
<> 144:ef7eb2e8f9f7 52 static inline void inc_current_cnt(uint32_t inc) {
<> 144:ef7eb2e8f9f7 53
<> 144:ef7eb2e8f9f7 54 // Overflow the ticker when the us ticker overflows
<> 144:ef7eb2e8f9f7 55 current_cnt += inc;
<> 144:ef7eb2e8f9f7 56 if (current_cnt > MAX_TICK_VAL) {
<> 144:ef7eb2e8f9f7 57 current_cnt -= (MAX_TICK_VAL + 1);
<> 144:ef7eb2e8f9f7 58 }
<> 144:ef7eb2e8f9f7 59 }
<> 144:ef7eb2e8f9f7 60
<> 144:ef7eb2e8f9f7 61 //******************************************************************************
<> 144:ef7eb2e8f9f7 62 static inline int event_passed(uint64_t current, uint64_t event) {
<> 144:ef7eb2e8f9f7 63
<> 144:ef7eb2e8f9f7 64 // Determine if the event has already happened.
<> 144:ef7eb2e8f9f7 65 // If the event is behind the current ticker, within a window,
<> 144:ef7eb2e8f9f7 66 // then the event has already happened.
<> 144:ef7eb2e8f9f7 67 if (((current < tick_win) && ((event < current) ||
<> 144:ef7eb2e8f9f7 68 (event > (MAX_TICK_VAL - (tick_win - current))))) ||
<> 144:ef7eb2e8f9f7 69 ((event < current) && (event > (current - tick_win)))) {
<> 144:ef7eb2e8f9f7 70 return 1;
<> 144:ef7eb2e8f9f7 71 }
<> 144:ef7eb2e8f9f7 72
<> 144:ef7eb2e8f9f7 73 return 0;
<> 144:ef7eb2e8f9f7 74 }
<> 144:ef7eb2e8f9f7 75
<> 144:ef7eb2e8f9f7 76 //******************************************************************************
<> 144:ef7eb2e8f9f7 77 static inline uint64_t event_diff(uint64_t current, uint64_t event) {
<> 144:ef7eb2e8f9f7 78
<> 144:ef7eb2e8f9f7 79 // Check to see if the ticker will overflow before the event
<> 144:ef7eb2e8f9f7 80 if(current <= event) {
<> 144:ef7eb2e8f9f7 81 return (event - current);
<> 144:ef7eb2e8f9f7 82 }
<> 144:ef7eb2e8f9f7 83
<> 144:ef7eb2e8f9f7 84 return ((MAX_TICK_VAL - current) + event);
<> 144:ef7eb2e8f9f7 85 }
<> 144:ef7eb2e8f9f7 86
<> 144:ef7eb2e8f9f7 87 //******************************************************************************
<> 144:ef7eb2e8f9f7 88 static void tmr_handler(void)
<> 144:ef7eb2e8f9f7 89 {
<> 144:ef7eb2e8f9f7 90 uint32_t term_cnt32 = US_TIMER->term_cnt32;
<> 144:ef7eb2e8f9f7 91 US_TIMER->term_cnt32 = 0xFFFFFFFF; // reset to max value to prevent further interrupts
<> 144:ef7eb2e8f9f7 92 US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt
<> 144:ef7eb2e8f9f7 93 NVIC_ClearPendingIRQ(US_TIMER_IRQn);
<> 144:ef7eb2e8f9f7 94
<> 144:ef7eb2e8f9f7 95 inc_current_cnt(term_cnt32);
<> 144:ef7eb2e8f9f7 96
<> 144:ef7eb2e8f9f7 97 if (event_passed(current_cnt + US_TIMER->count32, event_cnt )) {
<> 144:ef7eb2e8f9f7 98 // the timestamp has expired
<> 144:ef7eb2e8f9f7 99 event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value
<> 144:ef7eb2e8f9f7 100 us_ticker_irq_handler();
<> 144:ef7eb2e8f9f7 101 } else {
<> 144:ef7eb2e8f9f7 102
<> 144:ef7eb2e8f9f7 103 uint64_t diff = event_diff(current_cnt, event_cnt);
<> 144:ef7eb2e8f9f7 104 if (diff < (uint64_t)0xFFFFFFFF) {
<> 144:ef7eb2e8f9f7 105 // the event occurs before the next overflow
<> 144:ef7eb2e8f9f7 106 US_TIMER->term_cnt32 = diff;
<> 144:ef7eb2e8f9f7 107
<> 144:ef7eb2e8f9f7 108 // Since the timer keeps counting after the terminal value is reached, it is possible that the new
<> 144:ef7eb2e8f9f7 109 // terminal value is in the past.
<> 144:ef7eb2e8f9f7 110 if (US_TIMER->term_cnt32 < US_TIMER->count32) {
<> 144:ef7eb2e8f9f7 111 // the timestamp has expired
<> 144:ef7eb2e8f9f7 112 US_TIMER->term_cnt32 = 0xFFFFFFFF; // reset to max value to prevent further interrupts
<> 144:ef7eb2e8f9f7 113 US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt
<> 144:ef7eb2e8f9f7 114 NVIC_ClearPendingIRQ(US_TIMER_IRQn);
<> 144:ef7eb2e8f9f7 115 event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value
<> 144:ef7eb2e8f9f7 116 us_ticker_irq_handler();
<> 144:ef7eb2e8f9f7 117 }
<> 144:ef7eb2e8f9f7 118 }
<> 144:ef7eb2e8f9f7 119 }
<> 144:ef7eb2e8f9f7 120 }
<> 144:ef7eb2e8f9f7 121
<> 144:ef7eb2e8f9f7 122 //******************************************************************************
<> 144:ef7eb2e8f9f7 123 void us_ticker_init(void)
<> 144:ef7eb2e8f9f7 124 {
<> 144:ef7eb2e8f9f7 125 if (us_ticker_inited)
<> 144:ef7eb2e8f9f7 126 return;
<> 144:ef7eb2e8f9f7 127 us_ticker_inited = 1;
<> 144:ef7eb2e8f9f7 128
<> 144:ef7eb2e8f9f7 129 current_cnt = 0;
<> 144:ef7eb2e8f9f7 130 event_cnt = 0xFFFFFFFFFFFFFFFFULL; // reset to max value
<> 144:ef7eb2e8f9f7 131
<> 144:ef7eb2e8f9f7 132 if (SystemCoreClock <= 1000000) {
<> 144:ef7eb2e8f9f7 133 error("us_ticker cannot operate at this SystemCoreClock");
<> 144:ef7eb2e8f9f7 134 return;
<> 144:ef7eb2e8f9f7 135 }
<> 144:ef7eb2e8f9f7 136
<> 144:ef7eb2e8f9f7 137 // Configure timer for 32-bit continuous mode with /1 prescaler
<> 144:ef7eb2e8f9f7 138 US_TIMER->ctrl = MXC_E_TMR_MODE_CONTINUOUS << MXC_F_TMR_CTRL_MODE_POS | (0 << MXC_F_TMR_CTRL_PRESCALE_POS);
<> 144:ef7eb2e8f9f7 139 ticks_per_us = SystemCoreClock / 1000000;
<> 144:ef7eb2e8f9f7 140
<> 144:ef7eb2e8f9f7 141 // Set the tick window to 10ms
<> 144:ef7eb2e8f9f7 142 tick_win = SystemCoreClock/100;
<> 144:ef7eb2e8f9f7 143
<> 144:ef7eb2e8f9f7 144 // Set timer overflow to the max
<> 144:ef7eb2e8f9f7 145 US_TIMER->term_cnt32 = 0xFFFFFFFF;
<> 144:ef7eb2e8f9f7 146 US_TIMER->pwm_cap32 = 0xFFFFFFFF;
<> 144:ef7eb2e8f9f7 147 US_TIMER->count32 = 0;
<> 144:ef7eb2e8f9f7 148
<> 144:ef7eb2e8f9f7 149 US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear pending interrupts
<> 144:ef7eb2e8f9f7 150
<> 144:ef7eb2e8f9f7 151 NVIC_SetVector(US_TIMER_IRQn, (uint32_t)tmr_handler);
<> 144:ef7eb2e8f9f7 152 NVIC_EnableIRQ(US_TIMER_IRQn);
<> 144:ef7eb2e8f9f7 153
<> 144:ef7eb2e8f9f7 154 US_TIMER->inten |= MXC_F_TMR_INTEN_TIMER0; // enable interrupts
<> 144:ef7eb2e8f9f7 155 US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer
<> 144:ef7eb2e8f9f7 156 }
<> 144:ef7eb2e8f9f7 157
<> 144:ef7eb2e8f9f7 158 //******************************************************************************
<> 144:ef7eb2e8f9f7 159 void us_ticker_deinit(void)
<> 144:ef7eb2e8f9f7 160 {
<> 144:ef7eb2e8f9f7 161 US_TIMER->ctrl = 0; // disable timer
<> 144:ef7eb2e8f9f7 162 US_TIMER->inten = 0; // disable interrupts
<> 144:ef7eb2e8f9f7 163 US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupts
<> 144:ef7eb2e8f9f7 164 us_ticker_inited = 0;
<> 144:ef7eb2e8f9f7 165 }
<> 144:ef7eb2e8f9f7 166
<> 144:ef7eb2e8f9f7 167 //******************************************************************************
<> 144:ef7eb2e8f9f7 168 uint32_t us_ticker_read(void)
<> 144:ef7eb2e8f9f7 169 {
<> 144:ef7eb2e8f9f7 170 uint64_t current_cnt1, current_cnt2;
<> 144:ef7eb2e8f9f7 171 uint32_t term_cnt, tmr_cnt;
<> 144:ef7eb2e8f9f7 172 uint32_t intfl1, intfl2;
<> 144:ef7eb2e8f9f7 173
<> 144:ef7eb2e8f9f7 174 if (!us_ticker_inited)
<> 144:ef7eb2e8f9f7 175 us_ticker_init();
<> 144:ef7eb2e8f9f7 176
<> 144:ef7eb2e8f9f7 177 // Ensure coherency between current_cnt and US_TIMER->count32
<> 144:ef7eb2e8f9f7 178 do {
<> 144:ef7eb2e8f9f7 179 current_cnt1 = current_cnt;
<> 144:ef7eb2e8f9f7 180 intfl1 = US_TIMER->intfl;
<> 144:ef7eb2e8f9f7 181 term_cnt = US_TIMER->term_cnt32;
<> 144:ef7eb2e8f9f7 182 tmr_cnt = US_TIMER->count32;
<> 144:ef7eb2e8f9f7 183 intfl2 = US_TIMER->intfl;
<> 144:ef7eb2e8f9f7 184 current_cnt2 = current_cnt;
<> 144:ef7eb2e8f9f7 185 } while ((current_cnt1 != current_cnt2) || (intfl1 != intfl2));
<> 144:ef7eb2e8f9f7 186
<> 144:ef7eb2e8f9f7 187 // Account for an unserviced interrupt
<> 144:ef7eb2e8f9f7 188 if (intfl1) {
<> 144:ef7eb2e8f9f7 189 current_cnt1 += term_cnt;
<> 144:ef7eb2e8f9f7 190 }
<> 144:ef7eb2e8f9f7 191
<> 144:ef7eb2e8f9f7 192 current_cnt1 += tmr_cnt;
<> 144:ef7eb2e8f9f7 193
<> 144:ef7eb2e8f9f7 194 return (current_cnt1 / ticks_per_us);
<> 144:ef7eb2e8f9f7 195 }
<> 144:ef7eb2e8f9f7 196
<> 144:ef7eb2e8f9f7 197 //******************************************************************************
<> 144:ef7eb2e8f9f7 198 void us_ticker_set_interrupt(timestamp_t timestamp)
<> 144:ef7eb2e8f9f7 199 {
<> 144:ef7eb2e8f9f7 200 // Note: interrupts are disabled before this function is called.
<> 144:ef7eb2e8f9f7 201
<> 144:ef7eb2e8f9f7 202 US_TIMER->ctrl &= ~MXC_F_TMR_CTRL_ENABLE0; // disable timer
<> 144:ef7eb2e8f9f7 203
<> 144:ef7eb2e8f9f7 204 if (US_TIMER->intfl) {
<> 144:ef7eb2e8f9f7 205 US_TIMER->intfl = (MXC_F_TMR_INTFL_TIMER0 | MXC_F_TMR_INTFL_TIMER1); // clear interrupt
<> 144:ef7eb2e8f9f7 206 NVIC_ClearPendingIRQ(US_TIMER_IRQn);
<> 144:ef7eb2e8f9f7 207 inc_current_cnt(US_TIMER->term_cnt32);
<> 144:ef7eb2e8f9f7 208 }
<> 144:ef7eb2e8f9f7 209
<> 144:ef7eb2e8f9f7 210 // add and reset the current count value
<> 144:ef7eb2e8f9f7 211 inc_current_cnt(US_TIMER->count32);
<> 144:ef7eb2e8f9f7 212 US_TIMER->count32 = 0;
<> 144:ef7eb2e8f9f7 213
<> 144:ef7eb2e8f9f7 214 // add the number of cycles that the timer is disabled here for
<> 144:ef7eb2e8f9f7 215 inc_current_cnt(200);
<> 144:ef7eb2e8f9f7 216
<> 144:ef7eb2e8f9f7 217 event_cnt = (uint64_t)timestamp * ticks_per_us;
<> 144:ef7eb2e8f9f7 218
<> 144:ef7eb2e8f9f7 219 // Check to see if the event has already passed
<> 144:ef7eb2e8f9f7 220 if (!event_passed(current_cnt, event_cnt)) {
<> 144:ef7eb2e8f9f7 221 uint64_t diff = event_diff(current_cnt, event_cnt);
<> 144:ef7eb2e8f9f7 222 if (diff < (uint64_t)0xFFFFFFFF) {
<> 144:ef7eb2e8f9f7 223 // the event occurs before the next overflow
<> 144:ef7eb2e8f9f7 224 US_TIMER->term_cnt32 = diff;
<> 144:ef7eb2e8f9f7 225 } else {
<> 144:ef7eb2e8f9f7 226 // the event occurs after the next overflow
<> 144:ef7eb2e8f9f7 227 US_TIMER->term_cnt32 = 0xFFFFFFFF; // set to max
<> 144:ef7eb2e8f9f7 228 }
<> 144:ef7eb2e8f9f7 229 } else {
<> 144:ef7eb2e8f9f7 230 // the requested timestamp occurs in the past
<> 144:ef7eb2e8f9f7 231 // set the timer up to immediately expire
<> 144:ef7eb2e8f9f7 232 US_TIMER->term_cnt32 = 1;
<> 144:ef7eb2e8f9f7 233 }
<> 144:ef7eb2e8f9f7 234 US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer
<> 144:ef7eb2e8f9f7 235 }
<> 144:ef7eb2e8f9f7 236
<> 144:ef7eb2e8f9f7 237 //******************************************************************************
<> 144:ef7eb2e8f9f7 238 void us_ticker_disable_interrupt(void)
<> 144:ef7eb2e8f9f7 239 {
<> 144:ef7eb2e8f9f7 240 // There are no more events, set timer overflow to the max
<> 144:ef7eb2e8f9f7 241 US_TIMER->term_cnt32 = 0xFFFFFFFF;
<> 144:ef7eb2e8f9f7 242 }
<> 144:ef7eb2e8f9f7 243
<> 144:ef7eb2e8f9f7 244 //******************************************************************************
<> 144:ef7eb2e8f9f7 245 void us_ticker_clear_interrupt(void)
<> 144:ef7eb2e8f9f7 246 {
<> 144:ef7eb2e8f9f7 247 // cleared in the local handler
<> 144:ef7eb2e8f9f7 248 }
<> 144:ef7eb2e8f9f7 249
<> 144:ef7eb2e8f9f7 250 //******************************************************************************
<> 144:ef7eb2e8f9f7 251 void us_ticker_set(timestamp_t timestamp)
<> 144:ef7eb2e8f9f7 252 {
<> 144:ef7eb2e8f9f7 253 US_TIMER->ctrl &= ~MXC_F_TMR_CTRL_ENABLE0; // disable timer
<> 144:ef7eb2e8f9f7 254 current_cnt = (uint64_t)timestamp * ticks_per_us;
<> 144:ef7eb2e8f9f7 255 US_TIMER->count32 = 0;
<> 144:ef7eb2e8f9f7 256 US_TIMER->term_cnt32 = 0xFFFFFFFF;
<> 144:ef7eb2e8f9f7 257 US_TIMER->ctrl |= MXC_F_TMR_CTRL_ENABLE0; // enable timer
<> 144:ef7eb2e8f9f7 258
<> 144:ef7eb2e8f9f7 259 if (((uint64_t)timestamp * ticks_per_us) >= event_cnt) {
<> 144:ef7eb2e8f9f7 260 // The next timestamp has elapsed. Trigger the interrupt to handle it.
<> 144:ef7eb2e8f9f7 261 NVIC_SetPendingIRQ(US_TIMER_IRQn);
<> 144:ef7eb2e8f9f7 262 }
<> 144:ef7eb2e8f9f7 263 }