tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/rtc_api.c

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #include "rtc_api.h"
  17
  18 // ensure rtc is running (unchanged if already running)
  19
  20 /* Setup the RTC based on a time structure, ensuring RTC is enabled
  21  *
  22  * Can be clocked by a 32.768KHz oscillator or prescale divider based on the APB clock
  23  * - We want to use the 32khz clock, allowing for sleep mode
  24  *
  25  * Most registers are not changed by a Reset
  26  * - We must initialize these registers between power-on and setting the RTC into operation
  27
  28  * Clock Control Register
  29  *  RTC_CCR[0] : Enable - 0 = Disabled, 1 = Enabled
  30  *  RTC_CCR[1] : Reset - 0 = Normal, 1 = Reset
  31  *  RTC_CCR[4] : Clock Source - 0 = Prescaler, 1 = 32k Xtal
  32  *
  33  * The RTC may already be running, so we should set it up
  34  * without impacting if it is the case
  35  */
  36 void rtc_init(void) {
  37     LPC_SC->PCONP |= 0x200; // Ensure power is on
  38     LPC_RTC->CCR = 0x00;
  39
  40     LPC_RTC->CCR |= 1 << 0; // Ensure the RTC is enabled
  41 }
  42
  43 void rtc_free(void) {
  44     // [TODO]
  45 }
  46
  47 /*
  48  * Little check routine to see if the RTC has been enabled
  49  *
  50  * Clock Control Register
  51  *  RTC_CCR[0] : 0 = Disabled, 1 = Enabled
  52  *
  53  */
  54 int rtc_isenabled(void) {
  55     return(((LPC_RTC->CCR) & 0x01) != 0);
  56 }
  57
  58 /*
  59  * RTC Registers
  60  *  RTC_SEC        Seconds 0-59
  61  *  RTC_MIN        Minutes 0-59
  62  *  RTC_HOUR    Hour 0-23
  63  *  RTC_DOM        Day of Month 1-28..31
  64  *  RTC_DOW        Day of Week 0-6
  65  *  RTC_DOY        Day of Year 1-365
  66  *  RTC_MONTH    Month 1-12
  67  *  RTC_YEAR    Year 0-4095
  68  *
  69  * struct tm
  70  *  tm_sec        seconds after the minute 0-61
  71  *  tm_min        minutes after the hour 0-59
  72  *  tm_hour        hours since midnight 0-23
  73  *  tm_mday        day of the month 1-31
  74  *  tm_mon        months since January 0-11
  75  *  tm_year        years since 1900
  76  *  tm_wday        days since Sunday 0-6
  77  *  tm_yday        days since January 1 0-365
  78  *  tm_isdst    Daylight Saving Time flag
  79  */
  80 time_t rtc_read(void) {
  81     // Setup a tm structure based on the RTC
  82     struct tm timeinfo;
  83     timeinfo.tm_sec = LPC_RTC->SEC;
  84     timeinfo.tm_min = LPC_RTC->MIN;
  85     timeinfo.tm_hour = LPC_RTC->HOUR;
  86     timeinfo.tm_mday = LPC_RTC->DOM;
  87     timeinfo.tm_mon = LPC_RTC->MONTH - 1;
  88     timeinfo.tm_year = LPC_RTC->YEAR - 1900;
  89
  90     // Convert to timestamp
  91     time_t t = mktime(&timeinfo);
  92
  93     return t;
  94 }
  95
  96 void rtc_write(time_t t) {
  97     // Convert the time in to a tm
  98     struct tm *timeinfo = localtime(&t);
  99
 100     // Pause clock, and clear counter register (clears us count)
 101     LPC_RTC->CCR |= 2;
 102
 103     // Set the RTC
 104     LPC_RTC->SEC = timeinfo->tm_sec;
 105     LPC_RTC->MIN = timeinfo->tm_min;
 106     LPC_RTC->HOUR = timeinfo->tm_hour;
 107     LPC_RTC->DOM = timeinfo->tm_mday;
 108     LPC_RTC->MONTH = timeinfo->tm_mon + 1;
 109     LPC_RTC->YEAR = timeinfo->tm_year + 1900;
 110
 111     // Restart clock
 112     LPC_RTC->CCR &= ~((uint32_t)2);
 113 }