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/* mbed Microcontroller Library
* Copyright (c) 2006-2015 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "rtc_api.h"
static void init(void) {
// enable PORTC clock
SIM->SCGC5 |= SIM_SCGC5_PORTC_MASK;
// enable RTC clock
SIM->SCGC6 |= SIM_SCGC6_RTC_MASK;
// OSC32 as source
SIM->SOPT1 &= ~SIM_SOPT1_OSC32KSEL_MASK;
SIM->SOPT1 |= SIM_SOPT1_OSC32KSEL(0);
}
void rtc_init(void) {
init();
// Enable the oscillator
#if defined (TARGET_K20D50M)
RTC->CR |= RTC_CR_OSCE_MASK;
#else
// Teensy3.1 requires 20pF MCU loading capacitors for 32KHz RTC oscillator
/* RTC->CR: SC2P=0,SC4P=1,SC8P=0,SC16P=1,CLKO=0,OSCE=1,UM=0,SUP=0,SPE=0,SWR=0 */
RTC->CR |= RTC_CR_OSCE_MASK |RTC_CR_SC16P_MASK | RTC_CR_SC4P_MASK;
#endif
//Configure the TSR. default value: 1
RTC->TSR = 1;
// enable counter
RTC->SR |= RTC_SR_TCE_MASK;
}
void rtc_free(void) {
// [TODO]
}
/*
* Little check routine to see if the RTC has been enabled
* 0 = Disabled, 1 = Enabled
*/
int rtc_isenabled(void) {
// even if the RTC module is enabled,
// as we use RTC_CLKIN and an external clock,
// we need to reconfigure the pins. That is why we
// call init() if the rtc is enabled
// if RTC not enabled return 0
SIM->SCGC5 |= SIM_SCGC5_PORTC_MASK;
SIM->SCGC6 |= SIM_SCGC6_RTC_MASK;
if ((RTC->SR & RTC_SR_TCE_MASK) == 0)
return 0;
init();
return 1;
}
time_t rtc_read(void) {
return RTC->TSR;
}
void rtc_write(time_t t) {
// disable counter
RTC->SR &= ~RTC_SR_TCE_MASK;
// we do not write 0 into TSR
// to avoid invalid time
if (t == 0)
t = 1;
// write seconds
RTC->TSR = t;
// re-enable counter
RTC->SR |= RTC_SR_TCE_MASK;
}
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