Johannes Stratmann / mbed-dev

added prescaler for 16 bit pwm in LPC1347 target

Fork of mbed-dev by mbed official

targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/lp_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 * @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"
<> 144:ef7eb2e8f9f7 25 #if DEVICE_LOWPOWERTIMER
<> 144:ef7eb2e8f9f7 26
<> 144:ef7eb2e8f9f7 27 #include "rtc_api.h"
<> 144:ef7eb2e8f9f7 28 #include "rtc_api_HAL.h"
<> 144:ef7eb2e8f9f7 29 #include "lp_ticker_api.h"
<> 144:ef7eb2e8f9f7 30
<> 144:ef7eb2e8f9f7 31 #include "critical.h"
<> 144:ef7eb2e8f9f7 32 #if (defined RTCC_COUNT) && (RTCC_COUNT > 0)
<> 144:ef7eb2e8f9f7 33 #include "em_rtcc.h"
<> 144:ef7eb2e8f9f7 34 #endif
<> 144:ef7eb2e8f9f7 35
<> 144:ef7eb2e8f9f7 36 static int rtc_reserved = 0;
<> 144:ef7eb2e8f9f7 37
<> 144:ef7eb2e8f9f7 38 void lp_ticker_init()
<> 144:ef7eb2e8f9f7 39 {
<> 144:ef7eb2e8f9f7 40 if(!rtc_reserved) {
<> 144:ef7eb2e8f9f7 41 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 42 rtc_init_real(RTC_INIT_LPTIMER);
<> 144:ef7eb2e8f9f7 43 rtc_set_comp0_handler((uint32_t)lp_ticker_irq_handler);
<> 144:ef7eb2e8f9f7 44 rtc_reserved = 1;
<> 144:ef7eb2e8f9f7 45 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 46 }
<> 144:ef7eb2e8f9f7 47 }
<> 144:ef7eb2e8f9f7 48
<> 144:ef7eb2e8f9f7 49 void lp_ticker_free()
<> 144:ef7eb2e8f9f7 50 {
<> 144:ef7eb2e8f9f7 51 if(rtc_reserved) {
<> 144:ef7eb2e8f9f7 52 core_util_critical_section_enter();
<> 144:ef7eb2e8f9f7 53 rtc_free_real(RTC_INIT_LPTIMER);
<> 144:ef7eb2e8f9f7 54 rtc_reserved = 0;
<> 144:ef7eb2e8f9f7 55 core_util_critical_section_exit();
<> 144:ef7eb2e8f9f7 56 }
<> 144:ef7eb2e8f9f7 57 }
<> 144:ef7eb2e8f9f7 58
<> 144:ef7eb2e8f9f7 59 #ifndef RTCC_COUNT
<> 144:ef7eb2e8f9f7 60
<> 144:ef7eb2e8f9f7 61 /* RTC API */
<> 144:ef7eb2e8f9f7 62
<> 144:ef7eb2e8f9f7 63 void lp_ticker_set_interrupt(timestamp_t timestamp)
<> 144:ef7eb2e8f9f7 64 {
<> 144:ef7eb2e8f9f7 65 uint64_t timestamp_ticks;
<> 144:ef7eb2e8f9f7 66 uint64_t current_ticks = RTC_CounterGet();
<> 144:ef7eb2e8f9f7 67 timestamp_t current_time = ((uint64_t)(current_ticks * 1000000) / (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT));
<> 144:ef7eb2e8f9f7 68
<> 144:ef7eb2e8f9f7 69 /* Initialize RTC */
<> 144:ef7eb2e8f9f7 70 lp_ticker_init();
<> 144:ef7eb2e8f9f7 71
<> 144:ef7eb2e8f9f7 72 /* calculate offset value */
<> 144:ef7eb2e8f9f7 73 timestamp_t offset = timestamp - current_time;
<> 144:ef7eb2e8f9f7 74 if(offset > 0xEFFFFFFF) offset = 100;
<> 144:ef7eb2e8f9f7 75
<> 144:ef7eb2e8f9f7 76 /* map offset to RTC value */
<> 144:ef7eb2e8f9f7 77 // ticks = offset * RTC frequency div 1000000
<> 144:ef7eb2e8f9f7 78 timestamp_ticks = ((uint64_t)offset * (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT)) / 1000000;
<> 144:ef7eb2e8f9f7 79 timestamp_ticks += current_ticks;
<> 144:ef7eb2e8f9f7 80
<> 144:ef7eb2e8f9f7 81 /* RTC has 24 bit resolution */
<> 144:ef7eb2e8f9f7 82 timestamp_ticks &= 0xFFFFFF;
<> 144:ef7eb2e8f9f7 83
<> 144:ef7eb2e8f9f7 84 /* check for RTC limitation */
<> 144:ef7eb2e8f9f7 85 if((timestamp_ticks - RTC_CounterGet()) >= 0x800000) timestamp_ticks = RTC_CounterGet() + 2;
<> 144:ef7eb2e8f9f7 86
<> 144:ef7eb2e8f9f7 87 /* Set callback */
<> 144:ef7eb2e8f9f7 88 RTC_FreezeEnable(true);
<> 144:ef7eb2e8f9f7 89 RTC_CompareSet(0, (uint32_t)timestamp_ticks);
<> 144:ef7eb2e8f9f7 90 RTC_IntEnable(RTC_IF_COMP0);
<> 144:ef7eb2e8f9f7 91 RTC_FreezeEnable(false);
<> 144:ef7eb2e8f9f7 92 }
<> 144:ef7eb2e8f9f7 93
<> 144:ef7eb2e8f9f7 94 inline void lp_ticker_disable_interrupt()
<> 144:ef7eb2e8f9f7 95 {
<> 144:ef7eb2e8f9f7 96 RTC_IntDisable(RTC_IF_COMP0);
<> 144:ef7eb2e8f9f7 97 lp_ticker_free();
<> 144:ef7eb2e8f9f7 98 }
<> 144:ef7eb2e8f9f7 99
<> 144:ef7eb2e8f9f7 100 inline void lp_ticker_clear_interrupt()
<> 144:ef7eb2e8f9f7 101 {
<> 144:ef7eb2e8f9f7 102 RTC_IntClear(RTC_IF_COMP0);
<> 144:ef7eb2e8f9f7 103 }
<> 144:ef7eb2e8f9f7 104
<> 144:ef7eb2e8f9f7 105 timestamp_t lp_ticker_read()
<> 144:ef7eb2e8f9f7 106 {
<> 144:ef7eb2e8f9f7 107 lp_ticker_init();
<> 144:ef7eb2e8f9f7 108
<> 144:ef7eb2e8f9f7 109 uint64_t ticks_temp;
<> 144:ef7eb2e8f9f7 110 uint64_t ticks = RTC_CounterGet();
<> 144:ef7eb2e8f9f7 111
<> 144:ef7eb2e8f9f7 112 /* ticks = counter tick value
<> 144:ef7eb2e8f9f7 113 * timestamp = value in microseconds
<> 144:ef7eb2e8f9f7 114 * timestamp = ticks * 1.000.000 / RTC frequency
<> 144:ef7eb2e8f9f7 115 */
<> 144:ef7eb2e8f9f7 116
<> 144:ef7eb2e8f9f7 117 ticks_temp = (ticks * 1000000) / (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT);
<> 144:ef7eb2e8f9f7 118 return (timestamp_t) (ticks_temp & 0xFFFFFFFF);
<> 144:ef7eb2e8f9f7 119 }
<> 144:ef7eb2e8f9f7 120
<> 144:ef7eb2e8f9f7 121 #else
<> 144:ef7eb2e8f9f7 122
<> 144:ef7eb2e8f9f7 123 /* RTCC API */
<> 144:ef7eb2e8f9f7 124
<> 144:ef7eb2e8f9f7 125 void lp_ticker_set_interrupt(timestamp_t timestamp)
<> 144:ef7eb2e8f9f7 126 {
<> 144:ef7eb2e8f9f7 127 uint64_t timestamp_ticks;
<> 144:ef7eb2e8f9f7 128 uint64_t current_ticks = RTCC_CounterGet();
<> 144:ef7eb2e8f9f7 129 timestamp_t current_time = ((uint64_t)(current_ticks * 1000000) / (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT));
<> 144:ef7eb2e8f9f7 130
<> 144:ef7eb2e8f9f7 131 /* Initialize RTC */
<> 144:ef7eb2e8f9f7 132 lp_ticker_init();
<> 144:ef7eb2e8f9f7 133
<> 144:ef7eb2e8f9f7 134 /* calculate offset value */
<> 144:ef7eb2e8f9f7 135 timestamp_t offset = timestamp - current_time;
<> 144:ef7eb2e8f9f7 136 if(offset > 0xEFFFFFFF) offset = 100;
<> 144:ef7eb2e8f9f7 137
<> 144:ef7eb2e8f9f7 138 /* map offset to RTC value */
<> 144:ef7eb2e8f9f7 139 // ticks = offset * RTC frequency div 1000000
<> 144:ef7eb2e8f9f7 140 timestamp_ticks = ((uint64_t)offset * (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT)) / 1000000;
<> 144:ef7eb2e8f9f7 141 // checking the rounding. If timeout is wanted between RTCC ticks, irq should be configured to
<> 144:ef7eb2e8f9f7 142 // trigger in the latter RTCC-tick. Otherwise ticker-api fails to send timer event to its client
<> 144:ef7eb2e8f9f7 143 if(((timestamp_ticks * 1000000) / (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT)) < offset){
<> 144:ef7eb2e8f9f7 144 timestamp_ticks++;
<> 144:ef7eb2e8f9f7 145 }
<> 144:ef7eb2e8f9f7 146
<> 144:ef7eb2e8f9f7 147 timestamp_ticks += current_ticks;
<> 144:ef7eb2e8f9f7 148
<> 144:ef7eb2e8f9f7 149 /* RTCC has 32 bit resolution */
<> 144:ef7eb2e8f9f7 150 timestamp_ticks &= 0xFFFFFFFF;
<> 144:ef7eb2e8f9f7 151
<> 144:ef7eb2e8f9f7 152 /* check for RTCC limitation */
<> 144:ef7eb2e8f9f7 153 if((timestamp_ticks - RTCC_CounterGet()) >= 0x80000000) timestamp_ticks = RTCC_CounterGet() + 2;
<> 144:ef7eb2e8f9f7 154
<> 144:ef7eb2e8f9f7 155 /* init channel */
<> 144:ef7eb2e8f9f7 156 RTCC_CCChConf_TypeDef ccchConf = RTCC_CH_INIT_COMPARE_DEFAULT;
<> 144:ef7eb2e8f9f7 157 RTCC_ChannelInit(0,&ccchConf);
<> 144:ef7eb2e8f9f7 158 /* Set callback */
<> 144:ef7eb2e8f9f7 159 RTCC_ChannelCCVSet(0, (uint32_t)timestamp_ticks);
<> 144:ef7eb2e8f9f7 160 RTCC_IntEnable(RTCC_IF_CC0);
<> 144:ef7eb2e8f9f7 161 }
<> 144:ef7eb2e8f9f7 162
<> 144:ef7eb2e8f9f7 163 inline void lp_ticker_disable_interrupt()
<> 144:ef7eb2e8f9f7 164 {
<> 144:ef7eb2e8f9f7 165 RTCC_IntDisable(RTCC_IF_CC0);
<> 144:ef7eb2e8f9f7 166 lp_ticker_free();
<> 144:ef7eb2e8f9f7 167 }
<> 144:ef7eb2e8f9f7 168
<> 144:ef7eb2e8f9f7 169 inline void lp_ticker_clear_interrupt()
<> 144:ef7eb2e8f9f7 170 {
<> 144:ef7eb2e8f9f7 171 RTCC_IntClear(RTCC_IF_CC0);
<> 144:ef7eb2e8f9f7 172 }
<> 144:ef7eb2e8f9f7 173
<> 144:ef7eb2e8f9f7 174 timestamp_t lp_ticker_read()
<> 144:ef7eb2e8f9f7 175 {
<> 144:ef7eb2e8f9f7 176 lp_ticker_init();
<> 144:ef7eb2e8f9f7 177
<> 144:ef7eb2e8f9f7 178 uint64_t ticks_temp;
<> 144:ef7eb2e8f9f7 179 uint64_t ticks = RTCC_CounterGet();
<> 144:ef7eb2e8f9f7 180
<> 144:ef7eb2e8f9f7 181 /* ticks = counter tick value
<> 144:ef7eb2e8f9f7 182 * timestamp = value in microseconds
<> 144:ef7eb2e8f9f7 183 * timestamp = ticks * 1.000.000 / RTC frequency
<> 144:ef7eb2e8f9f7 184 */
<> 144:ef7eb2e8f9f7 185
<> 144:ef7eb2e8f9f7 186 ticks_temp = (ticks * 1000000) / (LOW_ENERGY_CLOCK_FREQUENCY / RTC_CLOCKDIV_INT);
<> 144:ef7eb2e8f9f7 187 return (timestamp_t) (ticks_temp & 0xFFFFFFFF);
<> 144:ef7eb2e8f9f7 188 }
<> 144:ef7eb2e8f9f7 189
<> 144:ef7eb2e8f9f7 190 #endif /* RTCC */
<> 144:ef7eb2e8f9f7 191
<> 144:ef7eb2e8f9f7 192 #endif