Ken Todotani / mbed-src

mbed library sources

Fork of mbed-src by mbed official

targets/hal/TARGET_STM/TARGET_DISCO_F100RB/us_ticker.c@304:89b9c3a9a045, 2014-08-29 (annotated)

Committer:
mbed_official
Date:
Fri Aug 29 17:15:07 2014 +0100
Revision:
304:89b9c3a9a045
Parent:
126:549ba18ddd81 
Synchronized with git revision 734f365d7da26ef199751f4b0d91611479b495ea



Full URL: https://github.com/mbedmicro/mbed/commit/734f365d7da26ef199751f4b0d91611479b495ea/



1. timestamp_t as an abstraction for time values managed by

   Ticker. Using uint64_t for timestamp_t allows a wraparound-free

   Ticker. This change forces us to update the definitions of usTicker

   for all platforms; but the changes beyond nRF51822 aren't major.



2. reduce power consumption on the nRF51822 by removing the need for

   the high-frequency processor timer; and reimplementing it using the

   RTC.



I've also replaced high-frequency clock with low-frequency external

clock during system startup of the nRF51822. This brings a major win

in power consumption.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 126:549ba18ddd81 1 /* mbed Microcontroller Library
mbed_official 126:549ba18ddd81 2 * Copyright (c) 2014, STMicroelectronics
mbed_official 126:549ba18ddd81 3 * All rights reserved.
mbed_official 126:549ba18ddd81 4 *
mbed_official 126:549ba18ddd81 5 * Redistribution and use in source and binary forms, with or without
mbed_official 126:549ba18ddd81 6 * modification, are permitted provided that the following conditions are met:
mbed_official 126:549ba18ddd81 7 *
mbed_official 126:549ba18ddd81 8 * 1. Redistributions of source code must retain the above copyright notice,
mbed_official 126:549ba18ddd81 9 * this list of conditions and the following disclaimer.
mbed_official 126:549ba18ddd81 10 * 2. Redistributions in binary form must reproduce the above copyright notice,
mbed_official 126:549ba18ddd81 11 * this list of conditions and the following disclaimer in the documentation
mbed_official 126:549ba18ddd81 12 * and/or other materials provided with the distribution.
mbed_official 126:549ba18ddd81 13 * 3. Neither the name of STMicroelectronics nor the names of its contributors
mbed_official 126:549ba18ddd81 14 * may be used to endorse or promote products derived from this software
mbed_official 126:549ba18ddd81 15 * without specific prior written permission.
mbed_official 126:549ba18ddd81 16 *
mbed_official 126:549ba18ddd81 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
mbed_official 126:549ba18ddd81 18 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
mbed_official 126:549ba18ddd81 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
mbed_official 126:549ba18ddd81 20 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
mbed_official 126:549ba18ddd81 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
mbed_official 126:549ba18ddd81 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
mbed_official 126:549ba18ddd81 23 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
mbed_official 126:549ba18ddd81 24 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
mbed_official 126:549ba18ddd81 25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
mbed_official 126:549ba18ddd81 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
mbed_official 126:549ba18ddd81 27 */
mbed_official 126:549ba18ddd81 28 #include <stddef.h>
mbed_official 126:549ba18ddd81 29 #include "us_ticker_api.h"
mbed_official 126:549ba18ddd81 30 #include "PeripheralNames.h"
mbed_official 126:549ba18ddd81 31
mbed_official 126:549ba18ddd81 32 // Timer selection:
mbed_official 126:549ba18ddd81 33 #define TIM_MST TIM1
mbed_official 126:549ba18ddd81 34 #define TIM_MST_UP_IRQ TIM1_UP_TIM16_IRQn
mbed_official 126:549ba18ddd81 35 #define TIM_MST_OC_IRQ TIM1_CC_IRQn
mbed_official 126:549ba18ddd81 36 #define TIM_MST_RCC RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE)
mbed_official 126:549ba18ddd81 37
mbed_official 126:549ba18ddd81 38 static int us_ticker_inited = 0;
mbed_official 126:549ba18ddd81 39 static volatile uint32_t SlaveCounter = 0;
mbed_official 126:549ba18ddd81 40 static volatile uint32_t oc_int_part = 0;
mbed_official 126:549ba18ddd81 41 static volatile uint16_t oc_rem_part = 0;
mbed_official 126:549ba18ddd81 42
mbed_official 126:549ba18ddd81 43 void set_compare(uint16_t count) {
mbed_official 126:549ba18ddd81 44 // Set new output compare value
mbed_official 126:549ba18ddd81 45 TIM_SetCompare1(TIM_MST, count);
mbed_official 126:549ba18ddd81 46 // Enable IT
mbed_official 126:549ba18ddd81 47 TIM_ITConfig(TIM_MST, TIM_IT_CC1, ENABLE);
mbed_official 126:549ba18ddd81 48 }
mbed_official 126:549ba18ddd81 49
mbed_official 126:549ba18ddd81 50 // Used to increment the slave counter
mbed_official 126:549ba18ddd81 51 static void tim_update_irq_handler(void) {
mbed_official 126:549ba18ddd81 52 if (TIM_GetITStatus(TIM_MST, TIM_IT_Update) == SET) {
mbed_official 126:549ba18ddd81 53 TIM_ClearITPendingBit(TIM_MST, TIM_IT_Update);
mbed_official 126:549ba18ddd81 54 SlaveCounter++;
mbed_official 126:549ba18ddd81 55 }
mbed_official 126:549ba18ddd81 56 }
mbed_official 126:549ba18ddd81 57
mbed_official 126:549ba18ddd81 58 // Used by interrupt system
mbed_official 126:549ba18ddd81 59 static void tim_oc_irq_handler(void) {
mbed_official 126:549ba18ddd81 60 uint16_t cval = TIM_MST->CNT;
mbed_official 126:549ba18ddd81 61
mbed_official 126:549ba18ddd81 62 // Clear interrupt flag
mbed_official 126:549ba18ddd81 63 if (TIM_GetITStatus(TIM_MST, TIM_IT_CC1) == SET) {
mbed_official 126:549ba18ddd81 64 TIM_ClearITPendingBit(TIM_MST, TIM_IT_CC1);
mbed_official 126:549ba18ddd81 65 }
mbed_official 126:549ba18ddd81 66
mbed_official 126:549ba18ddd81 67 if (oc_rem_part > 0) {
mbed_official 126:549ba18ddd81 68 set_compare(oc_rem_part); // Finish the remaining time left
mbed_official 126:549ba18ddd81 69 oc_rem_part = 0;
mbed_official 126:549ba18ddd81 70 }
mbed_official 126:549ba18ddd81 71 else {
mbed_official 126:549ba18ddd81 72 if (oc_int_part > 0) {
mbed_official 126:549ba18ddd81 73 set_compare(0xFFFF);
mbed_official 126:549ba18ddd81 74 oc_rem_part = cval; // To finish the counter loop the next time
mbed_official 126:549ba18ddd81 75 oc_int_part--;
mbed_official 126:549ba18ddd81 76 }
mbed_official 126:549ba18ddd81 77 else {
mbed_official 126:549ba18ddd81 78 us_ticker_irq_handler();
mbed_official 126:549ba18ddd81 79 }
mbed_official 126:549ba18ddd81 80 }
mbed_official 126:549ba18ddd81 81 }
mbed_official 126:549ba18ddd81 82
mbed_official 126:549ba18ddd81 83 void us_ticker_init(void) {
mbed_official 126:549ba18ddd81 84 TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
mbed_official 126:549ba18ddd81 85
mbed_official 126:549ba18ddd81 86 if (us_ticker_inited) return;
mbed_official 126:549ba18ddd81 87 us_ticker_inited = 1;
mbed_official 126:549ba18ddd81 88
mbed_official 126:549ba18ddd81 89 // Enable Timer clock
mbed_official 126:549ba18ddd81 90 TIM_MST_RCC;
mbed_official 126:549ba18ddd81 91
mbed_official 126:549ba18ddd81 92 // Configure time base
mbed_official 126:549ba18ddd81 93 TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
mbed_official 126:549ba18ddd81 94 TIM_TimeBaseStructure.TIM_Period = 0xFFFF;
mbed_official 304:89b9c3a9a045 95 TIM_TimeBaseStructure.TIM_Prescaler = (uint16_t)(SystemCoreClock / 1000000) - 1; // 1 �s tick
mbed_official 126:549ba18ddd81 96 TIM_TimeBaseStructure.TIM_ClockDivision = 0;
mbed_official 126:549ba18ddd81 97 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
mbed_official 126:549ba18ddd81 98 TIM_TimeBaseInit(TIM_MST, &TIM_TimeBaseStructure);
mbed_official 126:549ba18ddd81 99
mbed_official 126:549ba18ddd81 100 // Configure interrupts
mbed_official 126:549ba18ddd81 101 TIM_ITConfig(TIM_MST, TIM_IT_Update, ENABLE);
mbed_official 126:549ba18ddd81 102
mbed_official 126:549ba18ddd81 103 // Update interrupt used for 32-bit counter
mbed_official 126:549ba18ddd81 104 NVIC_SetVector(TIM_MST_UP_IRQ, (uint32_t)tim_update_irq_handler);
mbed_official 126:549ba18ddd81 105 NVIC_EnableIRQ(TIM_MST_UP_IRQ);
mbed_official 126:549ba18ddd81 106
mbed_official 126:549ba18ddd81 107 // Output compare interrupt used for timeout feature
mbed_official 126:549ba18ddd81 108 NVIC_SetVector(TIM_MST_OC_IRQ, (uint32_t)tim_oc_irq_handler);
mbed_official 126:549ba18ddd81 109 NVIC_EnableIRQ(TIM_MST_OC_IRQ);
mbed_official 126:549ba18ddd81 110
mbed_official 126:549ba18ddd81 111 // Enable timer
mbed_official 126:549ba18ddd81 112 TIM_Cmd(TIM_MST, ENABLE);
mbed_official 126:549ba18ddd81 113 }
mbed_official 126:549ba18ddd81 114
mbed_official 126:549ba18ddd81 115 uint32_t us_ticker_read() {
mbed_official 126:549ba18ddd81 116 uint32_t counter, counter2;
mbed_official 126:549ba18ddd81 117 if (!us_ticker_inited) us_ticker_init();
mbed_official 126:549ba18ddd81 118 // A situation might appear when Master overflows right after Slave is read and before the
mbed_official 126:549ba18ddd81 119 // new (overflowed) value of Master is read. Which would make the code below consider the
mbed_official 126:549ba18ddd81 120 // previous (incorrect) value of Slave and the new value of Master, which would return a
mbed_official 126:549ba18ddd81 121 // value in the past. Avoid this by computing consecutive values of the timer until they
mbed_official 126:549ba18ddd81 122 // are properly ordered.
mbed_official 126:549ba18ddd81 123 counter = (uint32_t)(SlaveCounter << 16);
mbed_official 126:549ba18ddd81 124 counter += TIM_MST->CNT;
mbed_official 126:549ba18ddd81 125 while (1) {
mbed_official 126:549ba18ddd81 126 counter2 = (uint32_t)(SlaveCounter << 16);
mbed_official 126:549ba18ddd81 127 counter2 += TIM_MST->CNT;
mbed_official 126:549ba18ddd81 128 if (counter2 > counter) {
mbed_official 126:549ba18ddd81 129 break;
mbed_official 126:549ba18ddd81 130 }
mbed_official 126:549ba18ddd81 131 counter = counter2;
mbed_official 126:549ba18ddd81 132 }
mbed_official 126:549ba18ddd81 133 return counter2;
mbed_official 126:549ba18ddd81 134 }
mbed_official 126:549ba18ddd81 135
mbed_official 304:89b9c3a9a045 136 void us_ticker_set_interrupt(timestamp_t timestamp) {
mbed_official 304:89b9c3a9a045 137 int delta = (int)((uint32_t)timestamp - us_ticker_read());
mbed_official 126:549ba18ddd81 138 uint16_t cval = TIM_MST->CNT;
mbed_official 126:549ba18ddd81 139
mbed_official 126:549ba18ddd81 140 if (delta <= 0) { // This event was in the past
mbed_official 126:549ba18ddd81 141 us_ticker_irq_handler();
mbed_official 126:549ba18ddd81 142 }
mbed_official 126:549ba18ddd81 143 else {
mbed_official 126:549ba18ddd81 144 oc_int_part = (uint32_t)(delta >> 16);
mbed_official 126:549ba18ddd81 145 oc_rem_part = (uint16_t)(delta & 0xFFFF);
mbed_official 126:549ba18ddd81 146 if (oc_rem_part <= (0xFFFF - cval)) {
mbed_official 126:549ba18ddd81 147 set_compare(cval + oc_rem_part);
mbed_official 126:549ba18ddd81 148 oc_rem_part = 0;
mbed_official 126:549ba18ddd81 149 } else {
mbed_official 126:549ba18ddd81 150 set_compare(0xFFFF);
mbed_official 126:549ba18ddd81 151 oc_rem_part = oc_rem_part - (0xFFFF - cval);
mbed_official 126:549ba18ddd81 152 }
mbed_official 126:549ba18ddd81 153 }
mbed_official 126:549ba18ddd81 154 }
mbed_official 126:549ba18ddd81 155
mbed_official 126:549ba18ddd81 156 void us_ticker_disable_interrupt(void) {
mbed_official 126:549ba18ddd81 157 TIM_ITConfig(TIM_MST, TIM_IT_CC1, DISABLE);
mbed_official 126:549ba18ddd81 158 }
mbed_official 126:549ba18ddd81 159
mbed_official 126:549ba18ddd81 160 void us_ticker_clear_interrupt(void) {
mbed_official 126:549ba18ddd81 161 if (TIM_GetITStatus(TIM_MST, TIM_IT_CC1) == SET) {
mbed_official 126:549ba18ddd81 162 TIM_ClearITPendingBit(TIM_MST, TIM_IT_CC1);
mbed_official 126:549ba18ddd81 163 }
mbed_official 126:549ba18ddd81 164 }