mbed official / mbed-dev

mbed library sources. Supersedes mbed-src.

Dependents:   Nucleo_Hello_Encoder BLE_iBeaconScan AM1805_DEMO DISCO-F429ZI_ExportTemplate1 ... more

targets/TARGET_Silicon_Labs/TARGET_EFM32/lp_ticker.c@189:f392fc9709a3, 2019-02-20 (annotated)

Committer:
AnnaBridge
Date:
Wed Feb 20 22:31:08 2019 +0000
Revision:
189:f392fc9709a3
Parent:
187:0387e8f68319 
mbed library release version 165

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 144:ef7eb2e8f9f7 1 /***************************************************************************//**
<> 144:ef7eb2e8f9f7 2 * @file lp_ticker.c
<> 144:ef7eb2e8f9f7 3 *******************************************************************************
<> 144:ef7eb2e8f9f7 4 * @section License
<> 144:ef7eb2e8f9f7 5 * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b>
<> 144:ef7eb2e8f9f7 6 *******************************************************************************
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * SPDX-License-Identifier: Apache-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Licensed under the Apache License, Version 2.0 (the "License"); you may
<> 144:ef7eb2e8f9f7 11 * not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 12 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 13 *
<> 144:ef7eb2e8f9f7 14 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 15 *
<> 144:ef7eb2e8f9f7 16 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 17 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
<> 144:ef7eb2e8f9f7 18 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 19 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 20 * limitations under the License.
<> 144:ef7eb2e8f9f7 21 *
<> 144:ef7eb2e8f9f7 22 ******************************************************************************/
<> 144:ef7eb2e8f9f7 23
<> 144:ef7eb2e8f9f7 24 #include "device.h"
<> 150:02e0a0aed4ec 25 #include "clocking.h"
Anna Bridge 186:707f6e361f3e 26 #if DEVICE_LPTICKER
<> 144:ef7eb2e8f9f7 27
AnnaBridge 181:57724642e740 28 /*******************************************************************************
AnnaBridge 181:57724642e740 29 * The Silicon Labs lp_ticker implementation is mapped on top of an extended RTC
AnnaBridge 181:57724642e740 30 * API, since the RTC is available in the lowest energy modes. By default, the
AnnaBridge 181:57724642e740 31 * RTC counter is configured to run at 4kHz, giving us a quarter-ms resolution
AnnaBridge 181:57724642e740 32 * for the low power timer, which should be good enough for a low power use
AnnaBridge 181:57724642e740 33 * case.
AnnaBridge 181:57724642e740 34 *
Anna Bridge 186:707f6e361f3e 35 * Mapping of mbed APIs to Silicon Labs peripherals:
Anna Bridge 186:707f6e361f3e 36 * ---: Does not meet mbed API requirements
Anna Bridge 186:707f6e361f3e 37 * X : Implemented to provide mbed API functionality
Anna Bridge 186:707f6e361f3e 38 *
Anna Bridge 186:707f6e361f3e 39 * --------------------------------------------
Anna Bridge 186:707f6e361f3e 40 * | ------------- | RTCC | BURTC | RTC | TIMER |
Anna Bridge 186:707f6e361f3e 41 * | rtc_api | X | X | --- | ----- |
Anna Bridge 186:707f6e361f3e 42 * | lp_ticker_api | X | | X | ----- |
Anna Bridge 186:707f6e361f3e 43 * | us_ticker_api | --- | ----- | --- | X |
Anna Bridge 186:707f6e361f3e 44 * --------------------------------------------
Anna Bridge 186:707f6e361f3e 45 *
AnnaBridge 181:57724642e740 46 * On Silicon Labs devices, the lowest width RTC implementation has a 24-bit
AnnaBridge 181:57724642e740 47 * counter, which gets extended with a further 32-bit software counter. This
AnnaBridge 181:57724642e740 48 * gives 56 bits of actual width, which with the default speed maps to
AnnaBridge 181:57724642e740 49 * 557462 years before the extended RTC counter wraps around. We are pretty
AnnaBridge 181:57724642e740 50 * certain no device is going to have that amount of uptime.
AnnaBridge 181:57724642e740 51 * (At max speed the wraparound is at 69730 years, which is unlikely as well)
AnnaBridge 181:57724642e740 52 ******************************************************************************/
AnnaBridge 181:57724642e740 53
AnnaBridge 187:0387e8f68319 54 #if defined(RTC_PRESENT) && !defined(RTCC_PRESENT)
Anna Bridge 186:707f6e361f3e 55 #include "em_rtc.h"
Anna Bridge 186:707f6e361f3e 56 #include "em_cmu.h"
<> 144:ef7eb2e8f9f7 57 #include "lp_ticker_api.h"
<> 160:d5399cc887bb 58 #include "mbed_critical.h"
<> 144:ef7eb2e8f9f7 59
Anna Bridge 186:707f6e361f3e 60 #if RTC_CLOCKDIV_INT > 16
Anna Bridge 186:707f6e361f3e 61 #error invalid prescaler value RTC_CLOCKDIV_INT, since LP ticker resolution will exceed 1ms.
Anna Bridge 186:707f6e361f3e 62 #endif
Anna Bridge 186:707f6e361f3e 63
Anna Bridge 186:707f6e361f3e 64 #define RTC_BITS (24U)
Anna Bridge 186:707f6e361f3e 65 #define RTC_MAX_VALUE (0xFFFFFFUL)
Anna Bridge 186:707f6e361f3e 66
Anna Bridge 186:707f6e361f3e 67 static bool rtc_inited = false;
Anna Bridge 186:707f6e361f3e 68
Anna Bridge 186:707f6e361f3e 69 const ticker_info_t* lp_ticker_get_info(void)
Anna Bridge 186:707f6e361f3e 70 {
Anna Bridge 186:707f6e361f3e 71 static const ticker_info_t rtc_info = {
Anna Bridge 186:707f6e361f3e 72 LOW_ENERGY_CLOCK_FREQUENCY,
Anna Bridge 186:707f6e361f3e 73 RTC_BITS
Anna Bridge 186:707f6e361f3e 74 };
Anna Bridge 186:707f6e361f3e 75 return &rtc_info;
Anna Bridge 186:707f6e361f3e 76 }
Anna Bridge 186:707f6e361f3e 77
Anna Bridge 186:707f6e361f3e 78 void RTC_IRQHandler(void)
Anna Bridge 186:707f6e361f3e 79 {
Anna Bridge 186:707f6e361f3e 80 uint32_t flags;
Anna Bridge 186:707f6e361f3e 81 flags = RTC_IntGet();
Anna Bridge 186:707f6e361f3e 82 if ((flags & RTC_IF_COMP0) && rtc_inited) {
Anna Bridge 186:707f6e361f3e 83 RTC_IntClear(RTC_IF_COMP0);
Anna Bridge 186:707f6e361f3e 84 lp_ticker_irq_handler();
Anna Bridge 186:707f6e361f3e 85 }
Anna Bridge 186:707f6e361f3e 86 }
<> 144:ef7eb2e8f9f7 87
<> 144:ef7eb2e8f9f7 88 void lp_ticker_init()
<> 144:ef7eb2e8f9f7 89 {
Anna Bridge 186:707f6e361f3e 90 core_util_critical_section_enter();
Anna Bridge 186:707f6e361f3e 91 if (!rtc_inited) {
Anna Bridge 186:707f6e361f3e 92 CMU_ClockEnable(cmuClock_RTC, true);
Anna Bridge 186:707f6e361f3e 93
Anna Bridge 186:707f6e361f3e 94 /* Initialize RTC */
Anna Bridge 186:707f6e361f3e 95 RTC_Init_TypeDef init = RTC_INIT_DEFAULT;
Anna Bridge 186:707f6e361f3e 96 init.enable = 1;
Anna Bridge 186:707f6e361f3e 97 /* Don't use compare register 0 as top value */
Anna Bridge 186:707f6e361f3e 98 init.comp0Top = 0;
Anna Bridge 186:707f6e361f3e 99
Anna Bridge 186:707f6e361f3e 100 /* Initialize */
Anna Bridge 186:707f6e361f3e 101 RTC_Init(&init);
Anna Bridge 186:707f6e361f3e 102 RTC_CounterSet(20);
Anna Bridge 186:707f6e361f3e 103
Anna Bridge 186:707f6e361f3e 104 /* Enable Interrupt from RTC */
Anna Bridge 186:707f6e361f3e 105 RTC_IntDisable(RTC_IF_COMP0);
Anna Bridge 186:707f6e361f3e 106 RTC_IntClear(RTC_IF_COMP0);
Anna Bridge 186:707f6e361f3e 107 NVIC_SetVector(RTC_IRQn, (uint32_t)RTC_IRQHandler);
Anna Bridge 186:707f6e361f3e 108 NVIC_EnableIRQ(RTC_IRQn);
Anna Bridge 186:707f6e361f3e 109
Anna Bridge 186:707f6e361f3e 110 rtc_inited = true;
Anna Bridge 186:707f6e361f3e 111 } else {
Anna Bridge 186:707f6e361f3e 112 /* Cancel current interrupt by virtue of calling init again */
Anna Bridge 186:707f6e361f3e 113 RTC_IntDisable(RTC_IF_COMP0);
Anna Bridge 186:707f6e361f3e 114 RTC_IntClear(RTC_IF_COMP0);
<> 144:ef7eb2e8f9f7 115 }
Anna Bridge 186:707f6e361f3e 116 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 117 }
<> 144:ef7eb2e8f9f7 118
<> 144:ef7eb2e8f9f7 119 void lp_ticker_free()
<> 144:ef7eb2e8f9f7 120 {
Anna Bridge 186:707f6e361f3e 121 /* Disable the RTC if it was inited and is no longer in use by anyone. */
Anna Bridge 186:707f6e361f3e 122 if (rtc_inited) {
Anna Bridge 186:707f6e361f3e 123 NVIC_DisableIRQ(RTC_IRQn);
Anna Bridge 186:707f6e361f3e 124 RTC_Reset();
Anna Bridge 186:707f6e361f3e 125 CMU_ClockEnable(cmuClock_RTC, false);
Anna Bridge 186:707f6e361f3e 126 rtc_inited = false;
<> 144:ef7eb2e8f9f7 127 }
Anna Bridge 186:707f6e361f3e 128 RTC_FreezeEnable(false);
<> 144:ef7eb2e8f9f7 129 }
<> 144:ef7eb2e8f9f7 130
<> 144:ef7eb2e8f9f7 131 void lp_ticker_set_interrupt(timestamp_t timestamp)
<> 144:ef7eb2e8f9f7 132 {
Anna Bridge 186:707f6e361f3e 133 RTC_IntDisable(RTC_IF_COMP0);
Anna Bridge 186:707f6e361f3e 134 RTC_IntClear(RTC_IF_COMP0);
Anna Bridge 186:707f6e361f3e 135 RTC_FreezeEnable(true);
Anna Bridge 186:707f6e361f3e 136 RTC_CompareSet(0, (uint32_t) (timestamp & RTC_MAX_VALUE));
Anna Bridge 186:707f6e361f3e 137 RTC_FreezeEnable(false);
Anna Bridge 186:707f6e361f3e 138 RTC_IntEnable(RTC_IF_COMP0);
<> 144:ef7eb2e8f9f7 139 }
<> 144:ef7eb2e8f9f7 140
Anna Bridge 186:707f6e361f3e 141 void lp_ticker_fire_interrupt(void)
AnnaBridge 174:b96e65c34a4d 142 {
Anna Bridge 186:707f6e361f3e 143 RTC_IntEnable(RTC_IF_COMP0);
Anna Bridge 186:707f6e361f3e 144 RTC_IntSet(RTC_IF_COMP0);
AnnaBridge 174:b96e65c34a4d 145 }
AnnaBridge 174:b96e65c34a4d 146
Anna Bridge 186:707f6e361f3e 147 void lp_ticker_disable_interrupt()
<> 144:ef7eb2e8f9f7 148 {
Anna Bridge 186:707f6e361f3e 149 RTC_IntDisable(RTC_IF_COMP0);
<> 144:ef7eb2e8f9f7 150 }
<> 144:ef7eb2e8f9f7 151
Anna Bridge 186:707f6e361f3e 152 void lp_ticker_clear_interrupt()
<> 144:ef7eb2e8f9f7 153 {
Anna Bridge 186:707f6e361f3e 154 RTC_IntClear(RTC_IF_COMP0);
<> 144:ef7eb2e8f9f7 155 }
<> 144:ef7eb2e8f9f7 156
<> 144:ef7eb2e8f9f7 157 timestamp_t lp_ticker_read()
<> 144:ef7eb2e8f9f7 158 {
Anna Bridge 186:707f6e361f3e 159 return (timestamp_t) RTC_CounterGet();
<> 144:ef7eb2e8f9f7 160 }
<> 144:ef7eb2e8f9f7 161
Anna Bridge 186:707f6e361f3e 162 #elif defined(RTCC_PRESENT)
Anna Bridge 186:707f6e361f3e 163 /* lp_ticker api is implemented in rtc_rtcc.c */
Anna Bridge 186:707f6e361f3e 164 #endif /* RTC_PRESENT */
Anna Bridge 186:707f6e361f3e 165 #endif /* DEVICE_LPTICKER */