rtc_api.c

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #include "rtc_api.h"
00017 
00018 #if DEVICE_RTC
00019 
00020 static void init(void) {
00021     // enable PORTC clock
00022     SIM->SCGC5 |= SIM_SCGC5_PORTC_MASK;
00023 
00024     // enable RTC clock
00025     SIM->SCGC6 |= SIM_SCGC6_RTC_MASK;
00026 
00027     /*
00028     * configure PTC1 with alternate function 1: RTC_CLKIN
00029     * As the kl25z board does not have a 32kHz osc,
00030     * we use an external clock generated by the
00031     * interface chip
00032     */
00033     PORTC->PCR[1] &= ~PORT_PCR_MUX_MASK;
00034     PORTC->PCR[1] = PORT_PCR_MUX(1);
00035 
00036     // select RTC_CLKIN as RTC clock source
00037     SIM->SOPT1 &= ~SIM_SOPT1_OSC32KSEL_MASK;
00038     SIM->SOPT1 |= SIM_SOPT1_OSC32KSEL(2);
00039 }
00040 
00041 void rtc_init(void) {
00042     init();
00043 
00044     //Configure the TSR. default value: 1
00045     RTC->TSR = 1;
00046 
00047     // enable counter
00048     RTC->SR |= RTC_SR_TCE_MASK;
00049 }
00050 
00051 void rtc_free(void) {
00052     // [TODO]
00053 }
00054 
00055 /*
00056  * Little check routine to see if the RTC has been enabled
00057  * 0 = Disabled, 1 = Enabled
00058  */
00059 int rtc_isenabled(void) {
00060     // even if the RTC module is enabled,
00061     // as we use RTC_CLKIN and an external clock,
00062     // we need to reconfigure the pins. That is why we
00063     // call init() if the rtc is enabled
00064 
00065     // if RTC not enabled return 0
00066     SIM->SCGC5 |= SIM_SCGC5_PORTC_MASK;
00067     SIM->SCGC6 |= SIM_SCGC6_RTC_MASK;
00068     if ((RTC->SR & RTC_SR_TCE_MASK) == 0)
00069         return 0;
00070 
00071     init();
00072     return 1;
00073 }
00074 
00075 time_t rtc_read(void) {
00076     return RTC->TSR;
00077 }
00078 
00079 void rtc_write(time_t t) {
00080     // disable counter
00081     RTC->SR &= ~RTC_SR_TCE_MASK;
00082 
00083     // we do not write 0 into TSR
00084     // to avoid invalid time
00085     if (t == 0)
00086         t = 1;
00087 
00088     // write seconds
00089     RTC->TSR = t;
00090 
00091     // re-enable counter
00092     RTC->SR |= RTC_SR_TCE_MASK;
00093 }
00094 
00095 #endif