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 // ensure rtc is running (unchanged if already running)
00021 
00022 /* Setup the RTC based on a time structure, ensuring RTC is enabled
00023  *
00024  * Can be clocked by a 32.768KHz oscillator or prescale divider based on the APB clock
00025  * - We want to use the 32khz clock, allowing for sleep mode
00026  *
00027  * Most registers are not changed by a Reset
00028  * - We must initialize these registers between power-on and setting the RTC into operation
00029 
00030  * Clock Control Register
00031  *  RTC_CCR[0] : Enable - 0 = Disabled, 1 = Enabled
00032  *  RTC_CCR[1] : Reset - 0 = Normal, 1 = Reset
00033  *  RTC_CCR[4] : Clock Source - 0 = Prescaler, 1 = 32k Xtal
00034  *
00035  * The RTC may already be running, so we should set it up
00036  * without impacting if it is the case
00037  */
00038 void rtc_init(void) {
00039     LPC_SC->PCONP |= 0x200; // Ensure power is on
00040     LPC_RTC->CCR = 0x00;
00041 
00042 // clock source on 2368 is special test mode on 1768!
00043 #ifdef TARGET_LPC2368
00044     LPC_RTC->CCR |= 1 << 4;  // Ensure clock source is 32KHz Xtal
00045 #endif
00046 
00047     LPC_RTC->CCR |= 1 << 0; // Ensure the RTC is enabled
00048 }
00049 
00050 void rtc_free(void) {
00051     // [TODO]
00052 }
00053 
00054 /*
00055  * Little check routine to see if the RTC has been enabled
00056  *
00057  * Clock Control Register
00058  *  RTC_CCR[0] : 0 = Disabled, 1 = Enabled
00059  *
00060  */
00061 
00062 int rtc_isenabled(void) {
00063     return(((LPC_RTC->CCR) & 0x01) != 0);
00064 }
00065 
00066 /*
00067  * RTC Registers
00068  *  RTC_SEC        Seconds 0-59
00069  *  RTC_MIN        Minutes 0-59
00070  *  RTC_HOUR    Hour 0-23
00071  *  RTC_DOM        Day of Month 1-28..31
00072  *  RTC_DOW        Day of Week 0-6
00073  *  RTC_DOY        Day of Year 1-365
00074  *  RTC_MONTH    Month 1-12
00075  *  RTC_YEAR    Year 0-4095
00076  *
00077  * struct tm
00078  *  tm_sec        seconds after the minute 0-61
00079  *  tm_min        minutes after the hour 0-59
00080  *  tm_hour        hours since midnight 0-23
00081  *  tm_mday        day of the month 1-31
00082  *  tm_mon        months since January 0-11
00083  *  tm_year        years since 1900
00084  *  tm_wday        days since Sunday 0-6
00085  *  tm_yday        days since January 1 0-365
00086  *  tm_isdst    Daylight Saving Time flag
00087  */
00088 time_t rtc_read(void) {
00089     // Setup a tm structure based on the RTC
00090     struct tm timeinfo;
00091     timeinfo.tm_sec = LPC_RTC->SEC;
00092     timeinfo.tm_min = LPC_RTC->MIN;
00093     timeinfo.tm_hour = LPC_RTC->HOUR;
00094     timeinfo.tm_mday = LPC_RTC->DOM;
00095     timeinfo.tm_mon = LPC_RTC->MONTH - 1;
00096     timeinfo.tm_year = LPC_RTC->YEAR - 1900;
00097 
00098     // Convert to timestamp
00099     time_t t = mktime(&timeinfo);
00100 
00101     return t;
00102 }
00103 
00104 void rtc_write(time_t t) {
00105     // Convert the time in to a tm
00106     struct tm *timeinfo = localtime(&t);
00107 
00108     // Pause clock, and clear counter register (clears us count)
00109     LPC_RTC->CCR |= 2;
00110 
00111     // Set the RTC
00112     LPC_RTC->SEC = timeinfo->tm_sec;
00113     LPC_RTC->MIN = timeinfo->tm_min;
00114     LPC_RTC->HOUR = timeinfo->tm_hour;
00115     LPC_RTC->DOM = timeinfo->tm_mday;
00116     LPC_RTC->MONTH = timeinfo->tm_mon + 1;
00117     LPC_RTC->YEAR = timeinfo->tm_year + 1900;
00118 
00119     // Restart clock
00120     LPC_RTC->CCR &= ~((uint32_t)2);
00121 }
00122 
00123 #endif