Ken Todotani / mbed-src

mbed library sources

Fork of mbed-src by mbed official

targets/hal/TARGET_Freescale/TARGET_KPSDK_MCUS/TARGET_K64F/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:
149:1fb5f62b92bd 
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 146:f64d43ff0c18 1 /* mbed Microcontroller Library
mbed_official 146:f64d43ff0c18 2 * Copyright (c) 2006-2013 ARM Limited
mbed_official 146:f64d43ff0c18 3 *
mbed_official 146:f64d43ff0c18 4 * Licensed under the Apache License, Version 2.0 (the "License");
mbed_official 146:f64d43ff0c18 5 * you may not use this file except in compliance with the License.
mbed_official 146:f64d43ff0c18 6 * You may obtain a copy of the License at
mbed_official 146:f64d43ff0c18 7 *
mbed_official 146:f64d43ff0c18 8 * http://www.apache.org/licenses/LICENSE-2.0
mbed_official 146:f64d43ff0c18 9 *
mbed_official 146:f64d43ff0c18 10 * Unless required by applicable law or agreed to in writing, software
mbed_official 146:f64d43ff0c18 11 * distributed under the License is distributed on an "AS IS" BASIS,
mbed_official 146:f64d43ff0c18 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
mbed_official 146:f64d43ff0c18 13 * See the License for the specific language governing permissions and
mbed_official 146:f64d43ff0c18 14 * limitations under the License.
mbed_official 146:f64d43ff0c18 15 */
mbed_official 146:f64d43ff0c18 16 #include <stddef.h>
mbed_official 146:f64d43ff0c18 17 #include "us_ticker_api.h"
mbed_official 146:f64d43ff0c18 18 #include "PeripheralNames.h"
mbed_official 146:f64d43ff0c18 19 #include "fsl_pit_hal.h"
mbed_official 146:f64d43ff0c18 20 #include "fsl_sim_hal.h"
mbed_official 146:f64d43ff0c18 21 #include "fsl_clock_manager.h"
mbed_official 146:f64d43ff0c18 22 #include "fsl_clock_configs.h"
mbed_official 146:f64d43ff0c18 23
mbed_official 146:f64d43ff0c18 24 static void pit_init(void);
mbed_official 146:f64d43ff0c18 25 static void lptmr_init(void);
mbed_official 146:f64d43ff0c18 26
mbed_official 146:f64d43ff0c18 27 static int us_ticker_inited = 0;
mbed_official 146:f64d43ff0c18 28
mbed_official 146:f64d43ff0c18 29 void us_ticker_init(void) {
mbed_official 146:f64d43ff0c18 30 if (us_ticker_inited) {
mbed_official 146:f64d43ff0c18 31 return;
mbed_official 146:f64d43ff0c18 32 }
mbed_official 146:f64d43ff0c18 33 us_ticker_inited = 1;
mbed_official 146:f64d43ff0c18 34
mbed_official 146:f64d43ff0c18 35 pit_init();
mbed_official 146:f64d43ff0c18 36 lptmr_init();
mbed_official 146:f64d43ff0c18 37 }
mbed_official 146:f64d43ff0c18 38
mbed_official 146:f64d43ff0c18 39
mbed_official 146:f64d43ff0c18 40 uint32_t us_ticker_read() {
mbed_official 146:f64d43ff0c18 41 if (!us_ticker_inited) {
mbed_official 146:f64d43ff0c18 42 us_ticker_init();
mbed_official 146:f64d43ff0c18 43 }
mbed_official 146:f64d43ff0c18 44
mbed_official 146:f64d43ff0c18 45 return ~(pit_hal_read_timer_count(1));
mbed_official 146:f64d43ff0c18 46 }
mbed_official 146:f64d43ff0c18 47 /******************************************************************************
mbed_official 146:f64d43ff0c18 48 * Timer for us timing.
mbed_official 146:f64d43ff0c18 49 ******************************************************************************/
mbed_official 146:f64d43ff0c18 50 static void pit_init(void) {
mbed_official 146:f64d43ff0c18 51 uint32_t busClock;
mbed_official 146:f64d43ff0c18 52
mbed_official 146:f64d43ff0c18 53 clock_hal_set_gate(kSimClockModulePIT, 0, true);
mbed_official 146:f64d43ff0c18 54 pit_hal_enable();
mbed_official 146:f64d43ff0c18 55 clock_manager_get_frequency(kBusClock, &busClock);
mbed_official 146:f64d43ff0c18 56 pit_hal_set_timer_period_count(0, busClock / 1000000 - 1);
mbed_official 146:f64d43ff0c18 57 pit_hal_set_timer_period_count(1, 0xFFFFFFFF);
mbed_official 146:f64d43ff0c18 58 pit_hal_configure_timer_chain(1, true);
mbed_official 146:f64d43ff0c18 59
mbed_official 146:f64d43ff0c18 60 pit_hal_timer_start(0);
mbed_official 146:f64d43ff0c18 61 pit_hal_timer_start(1);
mbed_official 146:f64d43ff0c18 62 }
mbed_official 146:f64d43ff0c18 63
mbed_official 146:f64d43ff0c18 64 /******************************************************************************
mbed_official 146:f64d43ff0c18 65 * Timer Event
mbed_official 146:f64d43ff0c18 66 *
mbed_official 146:f64d43ff0c18 67 * It schedules interrupts at given (32bit)us interval of time.
mbed_official 146:f64d43ff0c18 68 * It is implemented used the 16bit Low Power Timer that remains powered in all
mbed_official 146:f64d43ff0c18 69 * power modes.
mbed_official 146:f64d43ff0c18 70 ******************************************************************************/
mbed_official 146:f64d43ff0c18 71 static void lptmr_isr(void);
mbed_official 146:f64d43ff0c18 72
mbed_official 146:f64d43ff0c18 73 static void lptmr_init(void) {
mbed_official 146:f64d43ff0c18 74 clock_hal_set_gate(kSimClockModuleLPTIMER, 0, true);
mbed_official 146:f64d43ff0c18 75
mbed_official 146:f64d43ff0c18 76 /* Set interrupt handler */
mbed_official 146:f64d43ff0c18 77 NVIC_SetVector(LPTimer_IRQn, (uint32_t)lptmr_isr);
mbed_official 146:f64d43ff0c18 78 NVIC_EnableIRQ(LPTimer_IRQn);
mbed_official 146:f64d43ff0c18 79
mbed_official 146:f64d43ff0c18 80 /* TODO: check clock manager, due to nonstandard 50 MHz */
mbed_official 146:f64d43ff0c18 81 //No suitable external oscillator clock -> Use fast internal oscillator (4MHz / divider)
mbed_official 146:f64d43ff0c18 82 MCG->C1 |= MCG_C1_IRCLKEN_MASK;
mbed_official 146:f64d43ff0c18 83 MCG->C2 |= MCG_C2_IRCS_MASK;
mbed_official 146:f64d43ff0c18 84 LPTMR0->PSR = LPTMR_PSR_PCS(0);
mbed_official 146:f64d43ff0c18 85 switch (MCG->SC & MCG_SC_FCRDIV_MASK) {
mbed_official 146:f64d43ff0c18 86 case MCG_SC_FCRDIV(0): //4MHz
mbed_official 146:f64d43ff0c18 87 LPTMR0->PSR |= LPTMR_PSR_PRESCALE(1);
mbed_official 146:f64d43ff0c18 88 break;
mbed_official 146:f64d43ff0c18 89 case MCG_SC_FCRDIV(1): //2MHz
mbed_official 146:f64d43ff0c18 90 LPTMR0->PSR |= LPTMR_PSR_PRESCALE(0);
mbed_official 146:f64d43ff0c18 91 break;
mbed_official 146:f64d43ff0c18 92 default: //1MHz or anything else, in which case we put it on 1MHz
mbed_official 146:f64d43ff0c18 93 MCG->SC &= ~MCG_SC_FCRDIV_MASK;
mbed_official 146:f64d43ff0c18 94 MCG->SC |= MCG_SC_FCRDIV(2);
mbed_official 146:f64d43ff0c18 95 LPTMR0->PSR |= LPTMR_PSR_PBYP_MASK;
mbed_official 146:f64d43ff0c18 96 }
mbed_official 146:f64d43ff0c18 97 }
mbed_official 146:f64d43ff0c18 98
mbed_official 146:f64d43ff0c18 99 void us_ticker_disable_interrupt(void) {
mbed_official 146:f64d43ff0c18 100 BW_LPTMR_CSR_TIE(0);
mbed_official 146:f64d43ff0c18 101 }
mbed_official 146:f64d43ff0c18 102
mbed_official 146:f64d43ff0c18 103 void us_ticker_clear_interrupt(void) {
mbed_official 146:f64d43ff0c18 104 // we already clear interrupt in lptmr_isr
mbed_official 146:f64d43ff0c18 105 }
mbed_official 146:f64d43ff0c18 106
mbed_official 146:f64d43ff0c18 107 static uint32_t us_ticker_int_counter = 0;
mbed_official 146:f64d43ff0c18 108 static uint16_t us_ticker_int_remainder = 0;
mbed_official 146:f64d43ff0c18 109
mbed_official 146:f64d43ff0c18 110 static void lptmr_set(unsigned short count) {
mbed_official 146:f64d43ff0c18 111 HW_LPTMR_CSR_WR(0);
mbed_official 146:f64d43ff0c18 112 BW_LPTMR_CMR_COMPARE(count);
mbed_official 146:f64d43ff0c18 113 BW_LPTMR_CSR_TIE(1);
mbed_official 146:f64d43ff0c18 114 BW_LPTMR_CSR_TEN(1);
mbed_official 146:f64d43ff0c18 115 }
mbed_official 146:f64d43ff0c18 116
mbed_official 146:f64d43ff0c18 117 static void lptmr_isr(void) {
mbed_official 146:f64d43ff0c18 118 // write 1 to TCF to clear the LPT timer compare flag
mbed_official 146:f64d43ff0c18 119 BW_LPTMR_CSR_TCF(1);
mbed_official 146:f64d43ff0c18 120
mbed_official 146:f64d43ff0c18 121 if (us_ticker_int_counter > 0) {
mbed_official 146:f64d43ff0c18 122 lptmr_set(0xFFFF);
mbed_official 146:f64d43ff0c18 123 us_ticker_int_counter--;
mbed_official 146:f64d43ff0c18 124 } else {
mbed_official 146:f64d43ff0c18 125 if (us_ticker_int_remainder > 0) {
mbed_official 146:f64d43ff0c18 126 lptmr_set(us_ticker_int_remainder);
mbed_official 146:f64d43ff0c18 127 us_ticker_int_remainder = 0;
mbed_official 146:f64d43ff0c18 128 } else {
mbed_official 146:f64d43ff0c18 129 // This function is going to disable the interrupts if there are
mbed_official 146:f64d43ff0c18 130 // no other events in the queue
mbed_official 146:f64d43ff0c18 131 us_ticker_irq_handler();
mbed_official 146:f64d43ff0c18 132 }
mbed_official 146:f64d43ff0c18 133 }
mbed_official 146:f64d43ff0c18 134 }
mbed_official 146:f64d43ff0c18 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 146:f64d43ff0c18 138 if (delta <= 0) {
mbed_official 146:f64d43ff0c18 139 // This event was in the past:
mbed_official 146:f64d43ff0c18 140 us_ticker_irq_handler();
mbed_official 146:f64d43ff0c18 141 return;
mbed_official 146:f64d43ff0c18 142 }
mbed_official 146:f64d43ff0c18 143
mbed_official 146:f64d43ff0c18 144 us_ticker_int_counter = (uint32_t)(delta >> 16);
mbed_official 146:f64d43ff0c18 145 us_ticker_int_remainder = (uint16_t)(0xFFFF & delta);
mbed_official 146:f64d43ff0c18 146 if (us_ticker_int_counter > 0) {
mbed_official 146:f64d43ff0c18 147 lptmr_set(0xFFFF);
mbed_official 146:f64d43ff0c18 148 us_ticker_int_counter--;
mbed_official 146:f64d43ff0c18 149 } else {
mbed_official 146:f64d43ff0c18 150 lptmr_set(us_ticker_int_remainder);
mbed_official 146:f64d43ff0c18 151 us_ticker_int_remainder = 0;
mbed_official 146:f64d43ff0c18 152 }
mbed_official 146:f64d43ff0c18 153 }