pax_global_header00006660000000000000000000000064120244647410014516gustar00rootroot0000000000000052 comment=92882e2555bfbf66cb33ac9a8c8c9f7e62a37243 MCP79412RTC-1.0/000077500000000000000000000000001202446474100127555ustar00rootroot00000000000000MCP79412RTC-1.0/Examples/000077500000000000000000000000001202446474100145335ustar00rootroot00000000000000MCP79412RTC-1.0/Examples/PowerOutageLogger/000077500000000000000000000000001202446474100201345ustar00rootroot00000000000000MCP79412RTC-1.0/Examples/PowerOutageLogger/PowerOutageLogger.ino000066400000000000000000000173201202446474100242470ustar00rootroot00000000000000/*----------------------------------------------------------------------* * Power Outage Logger using Microchip MCP79412 RTC. * * Assumes the RTC is running and set to UTC. * * A maximum of 7 outages (power down/up times) can be logged in the * * RTC's SRAM. * * * * Jack Christensen 23Aug2012 * * * * This work is licensed under the Creative Commons Attribution- * * ShareAlike 3.0 Unported License. To view a copy of this license, * * visit http://creativecommons.org/licenses/by-sa/3.0/ or send a * * letter to Creative Commons, 171 Second Street, Suite 300, * * San Francisco, California, 94105, USA. * *----------------------------------------------------------------------*/ #include //http://github.com/JChristensen/MCP79412RTC #include //http://arduiniana.org/libraries/streaming/ #include //http://www.arduino.cc/playground/Code/Time #include //http://github.com/JChristensen/Timezone #include //http://arduino.cc/en/Reference/Wire (included with Arduino IDE) #define FIRST_OUTAGE_ADDR 0x08 //address of first outage timestamps in RTC SRAM #define OUTAGE_LENGTH 8 //8 data bytes for each outage (start and end timestamps, both are time_t values) #define MAX_OUTAGES 7 //maximum number of outage timestamp pairs that can be stored in SRAM #define MAX_OUTAGE_ADDR FIRST_OUTAGE_ADDR + OUTAGE_LENGTH * (MAX_OUTAGES - 1) //last outage address #define APP_ID 1 //APP_ID and 4 bytes of the RTC ID are stored in sram to provide //a way to recognize that the logging data structure has been initialized #define RTC_ID_LO 0x00 //lower 4 bytes of RTC unique ID are stored at sram addr 0x00 #define APP_ID_ADDR 0x04 //address of appID (1) #define NBR_OUTAGES_ADDR 0x05 //address containing number of outages currently stored in SRAM #define NEXT_OUTAGE_ADDR 0x06 //address containing pointer to next outage #define RFU_ADDR 0x07 //reserved for future use //US Eastern Time Zone (New York, Detroit) TimeChangeRule myDST = {"EDT", Second, Sun, Mar, 2, -240}; //Daylight time = UTC - 4 hours TimeChangeRule mySTD = {"EST", First, Sun, Nov, 2, -300}; //Standard time = UTC - 5 hours Timezone myTZ(myDST, mySTD); TimeChangeRule *tcr; //pointer to the time change rule, used to get TZ abbrev time_t utc, local, lastUTC; void setup() { Serial.begin(115200); setSyncProvider(RTC.get); //the function to get the time from the RTC Serial << "RTC SYNC"; if (timeStatus()!= timeSet) Serial << " FAIL"; Serial << endl; //logClear(); logOutage(); } void loop() { //nothing here in loop() has anything to do with logging power outages, //we just print the time every second so that something is happening. utc = now(); if (utc != lastUTC) { lastUTC = utc; local = myTZ.toLocal(utc, &tcr); Serial << endl; printTime(utc, "UTC"); printTime(local, tcr -> abbrev); } } //initialize the log data structure in the RTC SRAM if needed. //log a new outage if one occurred. //print out the outages logged. void logOutage(void) { union { uint8_t b[8]; struct { uint32_t hi; uint32_t lo; }; } uniqueID; //8-byte RTC "unique ID" with access to upper and lower halves uint32_t loID; //lower half of the unique ID read from sram uint8_t appID; //app ID read from sram uint8_t nOutage; //number of outages stored in sram uint8_t nextOutage; //address of next outage timestamps in sram uint8_t outageAddr; //outage address in sram time_t powerDown, powerUp; //power outage timestamps RTC.idRead(uniqueID.b); //get the RTC's ID loID = read32(RTC_ID_LO); //if already initialized, the lower half of the ID is stored at SRAM addr 0x00, appID = RTC.sramRead(APP_ID_ADDR); //and the app ID (1) is at addr 0x04. Serial << "RTC ID"; for (uint8_t i=0; i<8; i++) { Serial << (uniqueID.b[i] < 16 ? " 0" : " ") << _HEX(uniqueID.b[i]); } if ( loID != uniqueID.lo || appID != 1 ) { //logging initialized? write32(RTC_ID_LO, uniqueID.lo); //least significant half of the RTC unique ID RTC.sramWrite(APP_ID_ADDR, APP_ID); //app ID RTC.sramWrite(NBR_OUTAGES_ADDR, 0); //number of outages RTC.sramWrite(NEXT_OUTAGE_ADDR, FIRST_OUTAGE_ADDR); //next location for outage times RTC.sramWrite(RFU_ADDR, 0); //reserved for future use Serial << "Logging initialized" << endl; //no, do it now } //if an outage has occurred, record it if ( RTC.powerFail(&powerDown, &powerUp) ) { nOutage = RTC.sramRead(NBR_OUTAGES_ADDR); nextOutage = RTC.sramRead(NEXT_OUTAGE_ADDR); write32(nextOutage, powerDown); write32(nextOutage + 4, powerUp); nextOutage += OUTAGE_LENGTH; if (nextOutage > MAX_OUTAGE_ADDR) nextOutage = FIRST_OUTAGE_ADDR; RTC.sramWrite(NEXT_OUTAGE_ADDR, nextOutage); if (nOutage < MAX_OUTAGES) RTC.sramWrite(NBR_OUTAGES_ADDR, ++nOutage); } //print out all the outages logged nOutage = RTC.sramRead(NBR_OUTAGES_ADDR); nextOutage = RTC.sramRead(NEXT_OUTAGE_ADDR); outageAddr = nextOutage - OUTAGE_LENGTH; if (outageAddr < FIRST_OUTAGE_ADDR) outageAddr = MAX_OUTAGE_ADDR; Serial << endl << endl << "Power outages logged: " << _DEC(nOutage) << endl; for (uint8_t i=nOutage; i>0; i--) { powerDown = read32(outageAddr); powerUp = read32(outageAddr + 4); Serial << endl << _DEC(i) << ": Power down "; printTime(myTZ.toLocal(powerDown, &tcr), tcr -> abbrev); Serial << _DEC(i) << ": Power up "; printTime(myTZ.toLocal(powerUp, &tcr), tcr -> abbrev); outageAddr -= OUTAGE_LENGTH; if (outageAddr < FIRST_OUTAGE_ADDR) outageAddr = MAX_OUTAGE_ADDR; } } //destroy the logging data structure and log data void logClear(void) { for (uint8_t i=0; i #include #include //http://github.com/JChristensen/MCP79412RTC void setup() { Serial.begin(9600); setSyncProvider(RTC.get); // the function to get the time from the RTC if(timeStatus()!= timeSet) Serial.println("Unable to sync with the RTC"); else Serial.println("RTC has set the system time"); } void loop() { digitalClockDisplay(); delay(1000); } void digitalClockDisplay(){ // digital clock display of the time Serial.print(hour()); printDigits(minute()); printDigits(second()); Serial.print(" "); Serial.print(day()); Serial.print(" "); Serial.print(month()); Serial.print(" "); Serial.print(year()); Serial.println(); } void printDigits(int digits){ // utility function for digital clock display: prints preceding colon and leading 0 Serial.print(":"); if(digits < 10) Serial.print('0'); Serial.print(digits); } MCP79412RTC-1.0/Examples/rtcSet1/000077500000000000000000000000001202446474100160605ustar00rootroot00000000000000MCP79412RTC-1.0/Examples/rtcSet1/rtcSet1.ino000066400000000000000000000046171202446474100201240ustar00rootroot00000000000000/*----------------------------------------------------------------------* * Example sketch for Arduino MCP79412 Library by Jack Christensen * * * * Sets the RTC date and time to a hard-coded value. * * This is just a simple demonstration of setting the RTC time. * * Note that each time the sketch is run (or the microcontroller is * * reset), the RTC will be set to the same hard-coded time, so this * * example may be of limited usefulness as an actual clock. * * * * This work is licensed under the Creative Commons Attribution- * * ShareAlike 3.0 Unported License. To view a copy of this license, * * visit http://creativecommons.org/licenses/by-sa/3.0/ or send a * * letter to Creative Commons, 171 Second Street, Suite 300, * * San Francisco, California, 94105, USA. * *----------------------------------------------------------------------*/ #include //http://github.com/JChristensen/MCP79412RTC #include //http://www.arduino.cc/playground/Code/Time #include //http://arduino.cc/en/Reference/Wire (included with Arduino IDE) void setup(void) { delay(2000); Serial.begin(9600); setTime(23, 31, 30, 13, 2, 2009); //set the system time to 23h31m30s on 13Feb2009 //the setTime() function is from the Time.h library. //setTime(hour, minute, second, day, month, year); RTC.set(now()); //set the RTC from the system time } void loop(void) { printTime(now()); delay(1000); } //Print time (and date) given a time_t value void printTime(time_t t) { printI00(hour(t), ':'); printI00(minute(t), ':'); printI00(second(t), ' '); Serial.print(dayShortStr(weekday(t))); Serial.print(' '); printI00(day(t), ' '); Serial.print(monthShortStr(month(t))); Serial.print(' '); Serial.println(year(t)); } //Print an integer in "00" format (with leading zero), //followed by a delimiter. //Input value assumed to be between 0 and 99. void printI00(int val, char delim) { if (val < 10) Serial.print('0'); Serial.print(val); Serial.print(delim); return; } MCP79412RTC-1.0/Examples/rtcSet2/000077500000000000000000000000001202446474100160615ustar00rootroot00000000000000MCP79412RTC-1.0/Examples/rtcSet2/rtcSet2.ino000066400000000000000000000045731202446474100201270ustar00rootroot00000000000000/*----------------------------------------------------------------------* * Example sketch for Arduino MCP79412 Library by Jack Christensen * * * * Sets the RTC date and time to a hard-coded value, using a * * tmElements_t structure. The same structure is then used to * * read the RTC once per second. This sketch only uses the Time * * library for the tmElements_t definition. * * * * This is just a simple demonstration of setting the RTC time. * * Note that each time the sketch is run (or the microcontroller is * * reset), the RTC will be set to the same hard-coded time, so this * * example may be of limited usefulness as an actual clock. * * * * This work is licensed under the Creative Commons Attribution- * * ShareAlike 3.0 Unported License. To view a copy of this license, * * visit http://creativecommons.org/licenses/by-sa/3.0/ or send a * * letter to Creative Commons, 171 Second Street, Suite 300, * * San Francisco, California, 94105, USA. * *----------------------------------------------------------------------*/ #include //http://github.com/JChristensen/MCP79412RTC #include //http://www.arduino.cc/playground/Code/Time #include //http://arduino.cc/en/Reference/Wire (included with Arduino IDE) tmElements_t tm; void setup(void) { delay(2000); Serial.begin(9600); tm.Hour = 23; //set the tm structure to 23h31m30s on 13Feb2009 tm.Minute = 31; tm.Second = 30; tm.Year = 2009 - 1970; //tmElements_t.Year is the offset from 1970. tm.Month = 2; tm.Day = 13; RTC.write(tm); //set the RTC from the tm structure } void loop(void) { RTC.read(tm); Serial.print(tm.Hour, DEC); Serial.print(':'); Serial.print(tm.Minute,DEC); Serial.print(':'); Serial.print(tm.Second,DEC); Serial.print(' '); Serial.print(tm.Year + 1970, DEC); Serial.print('-'); Serial.print(tm.Month, DEC); Serial.print('-'); Serial.print(tm.Day, DEC); Serial.println(); delay(1000); } MCP79412RTC-1.0/Examples/rtcSet3/000077500000000000000000000000001202446474100160625ustar00rootroot00000000000000MCP79412RTC-1.0/Examples/rtcSet3/rtcSet3.ino000066400000000000000000000055511202446474100201260ustar00rootroot00000000000000/*----------------------------------------------------------------------* * Example sketch for Arduino MCP79412 Library by Jack Christensen * * * * Sets the RTC date and time to the sketch compile time. * * Re-running this sketch by pressing the reset button, etc., will * * cause the RTC time to be reset to the *same* compile time. * * Upload the sketch again to recompile it with the current time. * * * * This work is licensed under the Creative Commons Attribution- * * ShareAlike 3.0 Unported License. To view a copy of this license, * * visit http://creativecommons.org/licenses/by-sa/3.0/ or send a * * letter to Creative Commons, 171 Second Street, Suite 300, * * San Francisco, California, 94105, USA. * *----------------------------------------------------------------------*/ #include //http://github.com/JChristensen/MCP79412RTC #include //http://www.arduino.cc/playground/Code/Time #include //http://arduino.cc/en/Reference/Wire (included with Arduino IDE) void setup(void) { delay(2000); Serial.begin(9600); setTime(compileTime()); //set the system time to the sketch compile time RTC.set(now()); //set the RTC from the system time } void loop(void) { printTime(now()); delay(1000); } //Function to return the compile date and time as a time_t value time_t compileTime(void) { #define FUDGE 15 //fudge factor to allow for compile time (seconds, YMMV) char *compDate = __DATE__, *compTime = __TIME__, *months = "JanFebMarAprMayJunJulAugSepOctNovDec"; char chMon[3], *m; int d, y; tmElements_t tm; time_t t; strncpy(chMon, compDate, 3); chMon[3] = '\0'; m = strstr(months, chMon); tm.Month = ((m - months) / 3 + 1); tm.Day = atoi(compDate + 4); tm.Year = atoi(compDate + 7) - 1970; tm.Hour = atoi(compTime); tm.Minute = atoi(compTime + 3); tm.Second = atoi(compTime + 6); t = makeTime(tm); return t + FUDGE; //add fudge factor to allow for compile time } //Print time (and date) given a time_t value void printTime(time_t t) { printI00(hour(t), ':'); printI00(minute(t), ':'); printI00(second(t), ' '); Serial.print(dayShortStr(weekday(t))); Serial.print(' '); printI00(day(t), ' '); Serial.print(monthShortStr(month(t))); Serial.print(' '); Serial.println(year(t)); } //Print an integer in "00" format (with leading zero), //followed by a delimiter. //Input value assumed to be between 0 and 99. void printI00(int val, char delim) { if (val < 10) Serial.print('0'); Serial.print(val); Serial.print(delim); return; } MCP79412RTC-1.0/Examples/rtcSetSerial/000077500000000000000000000000001202446474100171375ustar00rootroot00000000000000MCP79412RTC-1.0/Examples/rtcSetSerial/rtcSetSerial.ino000066400000000000000000000103351202446474100222540ustar00rootroot00000000000000/*----------------------------------------------------------------------* * Example sketch for Arduino MCP79412 Library by Jack Christensen * * * * Set the RTC by entering a "Set" command on the serial monitor. * * Use a 24-hour clock and enter the command (case sensitive) exactly * * as follows: Set yyyy-mm-dd hh:mm:ss * * * * This work is licensed under the Creative Commons Attribution- * * ShareAlike 3.0 Unported License. To view a copy of this license, * * visit http://creativecommons.org/licenses/by-sa/3.0/ or send a * * letter to Creative Commons, 171 Second Street, Suite 300, * * San Francisco, California, 94105, USA. * *----------------------------------------------------------------------*/ #include //http://github.com/JChristensen/MCP79412RTC #include //http://www.arduino.cc/playground/Code/Time #include //http://arduino.cc/en/Reference/Wire (included with Arduino IDE) #define PRINT_INTERVAL 1000 //ms between printing the time unsigned long ms, msLast; void setup() { delay(2000); Serial.begin(9600); setSyncProvider(RTC.get); //the function to get the time from the RTC Serial.print("RTC SYNC"); if (timeStatus() != timeSet) Serial.print(" FAIL"); Serial.println(); } void loop(void) { ms = millis(); readCommand(); if (ms - msLast >= PRINT_INTERVAL) { msLast = ms; printTime(now()); } } //Read command from the Arduino serial monitor to set the RTC. //Case-sensitive and must be entered exactly as (24-hour clock): // Set yyyy-mm-dd hh:mm:ss void readCommand() { char cmd[24] = "Set yyyy-mm-dd hh:mm:ss"; static int i; tmElements_t tmSet; time_t tSet; if (Serial.available() >= 23) { //enough characters for the whole command? i = 0; //yes, read the available characters while (Serial.available() > 0) { if (i >= sizeof(cmd) - 1) { //more than we can enjoy flushInput(); //clear out the input buffer Serial.print("Too long: "); Serial.println(cmd); return; } delay(2); //let the next character trickle in cmd[i++] = char(Serial.read()); } cmd[i] = 0; //put in string terminator if (strncmp(cmd, "Set ", 4) == 0) { tmSet.Year = 1000 * (cmd[4] - '0') + 100 * (cmd[5] - '0') + 10 * (cmd[6] - '0') + cmd[7] - '0' - 1970; tmSet.Month = 10 * (cmd[9] - '0') + cmd[10] - '0'; tmSet.Day = 10 * (cmd[12] - '0') + cmd[13] - '0'; tmSet.Hour = 10 * (cmd[15] - '0') + cmd[16] - '0'; tmSet.Minute = 10 * (cmd[18] - '0') + cmd[19] - '0'; tmSet.Second = 10 * (cmd[21] - '0') + cmd[22] - '0'; tSet = makeTime(tmSet); //convert to time_t setTime(tSet); //set the system time RTC.set(now()); //set the rtc Serial.println("RTC set!"); flushInput(); //discard any extraneous trailing characters } else { Serial.print("Unknown: "); Serial.println(cmd); } } } void flushInput(void) { do { delay(2); Serial.read(); } while (Serial.available() > 0); } //Print time (and date) given a time_t value void printTime(time_t t) { printI00(hour(t), ':'); printI00(minute(t), ':'); printI00(second(t), ' '); Serial.print(dayShortStr(weekday(t))); Serial.print(' '); printI00(day(t), ' '); Serial.print(monthShortStr(month(t))); Serial.print(' '); Serial.println(year(t)); } //Print an integer in "00" format (with leading zero), //followed by a delimiter. //Input value assumed to be between 0 and 99. void printI00(int val, char delim) { if (val < 10) Serial.print('0'); Serial.print(val); Serial.print(delim); return; } MCP79412RTC-1.0/MCP79412RTC.cpp000066400000000000000000000605041202446474100150650ustar00rootroot00000000000000/*----------------------------------------------------------------------* * MCP79412RTC.cpp - Arduino library for the Microchip MCP79412 * * Real-Time Clock. This library is intended for use with the Arduino * * Time.h library, http://www.arduino.cc/playground/Code/Time * * * * This library is a drop-in replacement for the DS1307RTC.h library * * by Michael Margolis that is supplied with the Arduino Time library * * above. To change from using a DS1307 RTC to an MCP79412 RTC, it is * * only necessary to change the #include statement to include this * * library instead of DS1307RTC.h. * * * * In addition, this library implements functions to support the * * additional features of the MCP79412. * * * * Jack Christensen 29Jul2012 * * * * This work is licensed under the Creative Commons Attribution- * * ShareAlike 3.0 Unported License. To view a copy of this license, * * visit http://creativecommons.org/licenses/by-sa/3.0/ or send a * * letter to Creative Commons, 171 Second Street, Suite 300, * * San Francisco, California, 94105, USA. * *----------------------------------------------------------------------*/ #include #include "MCP79412RTC.h" /*----------------------------------------------------------------------* * Constructor. * *----------------------------------------------------------------------*/ MCP79412RTC::MCP79412RTC() { Wire.begin(); } /*----------------------------------------------------------------------* * Read the current time from the RTC and return it as a time_t value. * *----------------------------------------------------------------------*/ time_t MCP79412RTC::get() { tmElements_t tm; read(tm); return(makeTime(tm)); } /*----------------------------------------------------------------------* * Set the RTC to the given time_t value. * *----------------------------------------------------------------------*/ void MCP79412RTC::set(time_t t) { tmElements_t tm; breakTime(t, tm); write(tm); } /*----------------------------------------------------------------------* * Read the current time from the RTC and return it in a tmElements_t * * structure. * *----------------------------------------------------------------------*/ void MCP79412RTC::read(tmElements_t &tm) { Wire.beginTransmission(RTC_ADDR); i2cWrite(TIME_REG); Wire.endTransmission(); //request 7 bytes (secs, min, hr, dow, date, mth, yr) Wire.requestFrom(RTC_ADDR, tmNbrFields); tm.Second = bcd2dec(i2cRead() & ~_BV(ST)); tm.Minute = bcd2dec(i2cRead()); tm.Hour = bcd2dec(i2cRead() & ~_BV(HR1224)); //assumes 24hr clock tm.Wday = i2cRead() & ~(_BV(OSCON) | _BV(VBAT) | _BV(VBATEN)); //mask off OSCON, VBAT, VBATEN bits tm.Day = bcd2dec(i2cRead()); tm.Month = bcd2dec(i2cRead() & ~_BV(LP)); //mask off the leap year bit tm.Year = y2kYearToTm(bcd2dec(i2cRead())); } /*----------------------------------------------------------------------* * Set the RTC's time from a tmElements_t structure. * *----------------------------------------------------------------------*/ void MCP79412RTC::write(tmElements_t &tm) { Wire.beginTransmission(RTC_ADDR); i2cWrite(TIME_REG); i2cWrite(0x00); //stops the oscillator (Bit 7, ST == 0) i2cWrite(dec2bcd(tm.Minute)); i2cWrite(dec2bcd(tm.Hour)); //sets 24 hour format (Bit 6 == 0) i2cWrite(tm.Wday | _BV(VBATEN)); //enable battery backup operation i2cWrite(dec2bcd(tm.Day)); i2cWrite(dec2bcd(tm.Month)); i2cWrite(dec2bcd(tmYearToY2k(tm.Year))); Wire.endTransmission(); Wire.beginTransmission(RTC_ADDR); i2cWrite(TIME_REG); i2cWrite(dec2bcd(tm.Second) | _BV(ST)); //set the seconds and start the oscillator (Bit 7, ST == 1) Wire.endTransmission(); } /*----------------------------------------------------------------------* * Write a single byte to RTC RAM. * * Valid address range is 0x00 - 0x5F, no checking. * *----------------------------------------------------------------------*/ void MCP79412RTC::ramWrite(byte addr, byte value) { ramWrite(addr, &value, 1); } /*----------------------------------------------------------------------* * Write multiple bytes to RTC RAM. * * Valid address range is 0x00 - 0x5F, no checking. * * Number of bytes (nBytes) must be between 1 and 31 (Wire library * * limitation). * *----------------------------------------------------------------------*/ void MCP79412RTC::ramWrite(byte addr, byte *values, byte nBytes) { Wire.beginTransmission(RTC_ADDR); i2cWrite(addr); for (byte i=0; i= 1 && nBytes <= (BUFFER_LENGTH - 1) && (addr + nBytes) <= SRAM_SIZE) { ramWrite( (addr & (SRAM_SIZE - 1) ) + SRAM_START_ADDR, values, nBytes ); } } /*----------------------------------------------------------------------* * Read a single byte from Static RAM. * * Address (addr) is constrained to the range (0, 63). * *----------------------------------------------------------------------*/ byte MCP79412RTC::sramRead(byte addr) { byte value; ramRead( (addr & (SRAM_SIZE - 1) ) + SRAM_START_ADDR, &value, 1 ); return value; } /*----------------------------------------------------------------------* * Read multiple bytes from Static RAM. * * Address (addr) is constrained to the range (0, 63). * * Number of bytes (nBytes) must be between 1 and 32 (Wire library * * limitation). * * Invalid values for nBytes, or combinations of addr and * * nBytes that would result in addressing past the last byte of SRAM * * result in no action. * *----------------------------------------------------------------------*/ void MCP79412RTC::sramRead(byte addr, byte *values, byte nBytes) { if (nBytes >= 1 && nBytes <= BUFFER_LENGTH && (addr + nBytes) <= SRAM_SIZE) { ramRead((addr & (SRAM_SIZE - 1) ) + SRAM_START_ADDR, values, nBytes); } } /*----------------------------------------------------------------------* * Write a single byte to EEPROM. * * Address (addr) is constrained to the range (0, 127). * * Can't leverage page write function because a write can't start * * mid-page. * *----------------------------------------------------------------------*/ void MCP79412RTC::eepromWrite(byte addr, byte value) { Wire.beginTransmission(EEPROM_ADDR); i2cWrite( addr & (EEPROM_SIZE - 1) ); i2cWrite(value); Wire.endTransmission(); eepromWait(); } /*----------------------------------------------------------------------* * Write a page (or less) to EEPROM. An EEPROM page is 8 bytes. * * Address (addr) should be a page start address (0, 8, ..., 120), but * * is ruthlessly coerced into a valid value. * * Number of bytes (nBytes) must be between 1 and 8, other values * * result in no action. * *----------------------------------------------------------------------*/ void MCP79412RTC::eepromWrite(byte addr, byte *values, byte nBytes) { if (nBytes >= 1 && nBytes <= EEPROM_PAGE_SIZE) { Wire.beginTransmission(EEPROM_ADDR); i2cWrite( addr & ~(EEPROM_PAGE_SIZE - 1) & (EEPROM_SIZE - 1) ); for (byte i=0; i= 1 && nBytes <= BUFFER_LENGTH && (addr + nBytes) <= EEPROM_SIZE) { Wire.beginTransmission(EEPROM_ADDR); i2cWrite( addr & (EEPROM_SIZE - 1) ); Wire.endTransmission(); Wire.requestFrom( (uint8_t)EEPROM_ADDR, nBytes ); for (byte i=0; i= -127 && value <= 127) { calibVal = abs(value); if (value < 0) calibVal += 128; ramWrite(CALIB_REG, calibVal); } } /*----------------------------------------------------------------------* * Read the unique ID. * * Caller must provide an 8-byte array to contain the results. * *----------------------------------------------------------------------*/ void MCP79412RTC::idRead(byte *uniqueID) { Wire.beginTransmission(EEPROM_ADDR); i2cWrite(UNIQUE_ID_ADDR); Wire.endTransmission(); Wire.requestFrom( EEPROM_ADDR, UNIQUE_ID_SIZE ); for (byte i=0; i *powerUp) { --dn.Year; *powerDown = makeTime(dn); } } else return false; } /*----------------------------------------------------------------------* * Enable or disable the square wave output. * *----------------------------------------------------------------------*/ void MCP79412RTC::squareWave(uint8_t freq) { uint8_t ctrlReg; ramRead(CTRL_REG, &ctrlReg, 1); if (freq > 3) { ctrlReg &= ~_BV(SQWE); } else { ctrlReg = (ctrlReg & 0xF8) | _BV(SQWE) | freq; } ramWrite(CTRL_REG, &ctrlReg, 1); } /*----------------------------------------------------------------------* * Set an alarm time. Sets the alarm registers only, does not enable * * the alarm. See enableAlarm(). * *----------------------------------------------------------------------*/ void MCP79412RTC::setAlarm(uint8_t alarmNumber, time_t alarmTime) { tmElements_t tm; uint8_t day; //need to preserve bits in the day (of week) register alarmNumber &= 0x01; //ensure a valid alarm number ramRead( ALM0_DAY + alarmNumber * (ALM1_REG - ALM0_REG) , &day, 1); breakTime(alarmTime, tm); Wire.beginTransmission(RTC_ADDR); i2cWrite( ALM0_REG + alarmNumber * (ALM1_REG - ALM0_REG) ); i2cWrite(dec2bcd(tm.Second)); i2cWrite(dec2bcd(tm.Minute)); i2cWrite(dec2bcd(tm.Hour)); //sets 24 hour format (Bit 6 == 0) i2cWrite( (day & 0xF8) + tm.Wday ); i2cWrite(dec2bcd(tm.Day)); i2cWrite(dec2bcd(tm.Month)); Wire.endTransmission(); } /*----------------------------------------------------------------------* * Enable or disable an alarm, and set the trigger criteria, * * e.g. match only seconds, only minutes, entire time and date, etc. * *----------------------------------------------------------------------*/ void MCP79412RTC::enableAlarm(uint8_t alarmNumber, uint8_t alarmType) { uint8_t day; //alarm day register has config & flag bits uint8_t ctrl; //control register has alarm enable bits alarmNumber &= 0x01; //ensure a valid alarm number ramRead(CTRL_REG, &ctrl, 1); if (alarmType < ALM_DISABLE) { ramRead(ALM0_DAY + alarmNumber * (ALM1_REG - ALM0_REG), &day, 1); day = ( day & 0x87 ) | alarmType << 4; //reset interrupt flag, OR in the config bits ramWrite(ALM0_DAY + alarmNumber * (ALM1_REG - ALM0_REG), &day, 1); ctrl |= _BV(ALM0 + alarmNumber); //enable the alarm } else { ctrl &= ~(_BV(ALM0 + alarmNumber)); //disable the alarm } ramWrite(CTRL_REG, &ctrl, 1); } /*----------------------------------------------------------------------* * Returns true or false depending on whether the given alarm has been * * triggered, and resets the alarm "interrupt" flag. This is not a real * * interrupt, just a bit that's set when an alarm is triggered. * *----------------------------------------------------------------------*/ boolean MCP79412RTC::alarm(uint8_t alarmNumber) { uint8_t day; //alarm day register has config & flag bits alarmNumber &= 0x01; //ensure a valid alarm number ramRead( ALM0_DAY + alarmNumber * (ALM1_REG - ALM0_REG), &day, 1); if (day & _BV(ALMIF)) { day &= ~_BV(ALMIF); //turn off the alarm "interrupt" flag ramWrite( ALM0_DAY + alarmNumber * (ALM1_REG - ALM0_REG), &day, 1); return true; } else return false; } /*----------------------------------------------------------------------* * Sets the logic level on the MFP when it's not being used as a * * square wave or alarm output. The default is HIGH. * *----------------------------------------------------------------------*/ void MCP79412RTC::out(boolean level) { uint8_t ctrlReg; ramRead(CTRL_REG, &ctrlReg, 1); if (level) ctrlReg |= _BV(OUT); else ctrlReg &= ~_BV(OUT); ramWrite(CTRL_REG, &ctrlReg, 1); } /*----------------------------------------------------------------------* * Specifies the logic level on the Multi-Function Pin (MFP) when an * * alarm is triggered. The default is LOW. When both alarms are * * active, the two are ORed together to determine the level of the MFP. * * With alarm polarity set to LOW (the default), this causes the MFP * * to go low only when BOTH alarms are triggered. With alarm polarity * * set to HIGH, the MFP will go high when EITHER alarm is triggered. * * * * Note that the state of the MFP is independent of the alarm * * "interrupt" flags, and the alarm() function will indicate when an * * alarm is triggered regardless of the polarity. * *----------------------------------------------------------------------*/ void MCP79412RTC::alarmPolarity(boolean polarity) { uint8_t alm0Day; ramRead(ALM0_DAY, &alm0Day, 1); if (polarity) alm0Day |= _BV(OUT); else alm0Day &= ~_BV(OUT); ramWrite(ALM0_DAY, &alm0Day, 1); } /*----------------------------------------------------------------------* * Check to see if the RTC's oscillator is started (ST bit in seconds * * register). Returns true if started. * *----------------------------------------------------------------------*/ boolean MCP79412RTC::isRunning(void) { Wire.beginTransmission(RTC_ADDR); i2cWrite(TIME_REG); Wire.endTransmission(); //request just the seconds register Wire.requestFrom(RTC_ADDR, 1); return i2cRead() & _BV(ST); } /*----------------------------------------------------------------------* * Decimal-to-BCD conversion * *----------------------------------------------------------------------*/ uint8_t MCP79412RTC::dec2bcd(uint8_t num) { return ((num / 10 * 16) + (num % 10)); } /*----------------------------------------------------------------------* * BCD-to-Decimal conversion * *----------------------------------------------------------------------*/ uint8_t MCP79412RTC::bcd2dec(uint8_t num) { return ((num / 16 * 10) + (num % 16)); } MCP79412RTC RTC = MCP79412RTC(); //instantiate an RTC object MCP79412RTC-1.0/MCP79412RTC.h000066400000000000000000000153131202446474100145300ustar00rootroot00000000000000/*----------------------------------------------------------------------* * MCP79412RTC.h - Arduino library for the Microchip MCP79412 * * Real-Time Clock. This library is intended for use with the Arduino * * Time.h library, http://www.arduino.cc/playground/Code/Time * * * * This library is a drop-in replacement for the DS1307RTC.h library * * by Michael Margolis that is supplied with the Arduino Time library * * above. To change from using a DS1307 RTC to an MCP79412 RTC, it is * * only necessary to change the #include statement to include this * * library instead of DS1307RTC.h. * * * * In addition, this library implements functions to support the * * additional features of the MCP79412. * * * * Jack Christensen 29Jul2012 * * * * This work is licensed under the Creative Commons Attribution- * * ShareAlike 3.0 Unported License. To view a copy of this license, * * visit http://creativecommons.org/licenses/by-sa/3.0/ or send a * * letter to Creative Commons, 171 Second Street, Suite 300, * * San Francisco, California, 94105, USA. * *----------------------------------------------------------------------*/ #ifndef MCP79412RTC_h #define MCP79412RTC_h #include #if defined(ARDUINO) && ARDUINO >= 100 #include #else #include #endif //define release-independent I2C functions #if ARDUINO >= 100 #define i2cRead Wire.read #define i2cWrite Wire.write #else #define i2cRead Wire.receive #define i2cWrite Wire.send #endif //MCP7941x I2C Addresses #define RTC_ADDR 0x6F #define EEPROM_ADDR 0x57 //MCP7941x Register Addresses #define TIME_REG 0x00 //7 registers, Seconds, Minutes, Hours, DOW, Date, Month, Year #define DAY_REG 0x03 //the RTC Day register contains the OSCON, VBAT, and VBATEN bits #define YEAR_REG 0x06 //RTC year register #define CTRL_REG 0x07 //control register #define CALIB_REG 0x08 //calibration register #define UNLOCK_ID_REG 0x09 //unlock ID register #define ALM0_REG 0x0A //alarm 0, 6 registers, Seconds, Minutes, Hours, DOW, Date, Month #define ALM1_REG 0x11 //alarm 1, 6 registers, Seconds, Minutes, Hours, DOW, Date, Month #define ALM0_DAY 0x0D //DOW register has alarm config/flag bits #define PWRDWN_TS_REG 0x18 //power-down timestamp, 4 registers, Minutes, Hours, Date, Month #define PWRUP_TS_REG 0x1C //power-up timestamp, 4 registers, Minutes, Hours, Date, Month #define TIMESTAMP_SIZE 8 //number of bytes in the two timestamp registers #define SRAM_START_ADDR 0x20 //first SRAM address #define SRAM_SIZE 64 //number of bytes of SRAM #define EEPROM_SIZE 128 //number of bytes of EEPROM #define EEPROM_PAGE_SIZE 8 //number of bytes on an EEPROM page #define UNIQUE_ID_ADDR 0xF0 //starting address for unique ID #define UNIQUE_ID_SIZE 8 //number of bytes in unique ID //Control Register bits #define OUT 7 //sets logic level on MFP when not used as square wave output #define SQWE 6 //set to enable square wave output #define ALM1 5 //alarm 1 is active #define ALM0 4 //alarm 0 is active #define EXTOSC 3 //set to drive the RTC registers from an external oscillator instead of a crystal #define RS2 2 //RS2:0 set square wave output frequency: 0==1Hz, 1==4096Hz, 2==8192Hz, 3=32768Hz #define RS1 1 #define RS0 0 enum {SQWAVE_1_HZ, SQWAVE_4096_HZ, SQWAVE_8192_HZ, SQWAVE_32768_HZ, SQWAVE_NONE}; //Other Control Bits #define ST 7 //Seconds register (TIME_REG) oscillator start/stop bit, 1==Start, 0==Stop #define HR1224 6 //Hours register (TIME_REG+2) 12 or 24 hour mode (24 hour mode==0) #define AMPM 5 //Hours register (TIME_REG+2) AM/PM bit for 12 hour mode #define OSCON 5 //Day register (TIME_REG+3) oscillator running (set and cleared by hardware) #define VBAT 4 //Day register (TIME_REG+3) set by hardware when Vcc fails and RTC runs on battery. //VBAT is cleared by software, clearing VBAT also clears the timestamp registers #define VBATEN 3 //Day register (TIME_REG+3) VBATEN==1 enables backup battery, VBATEN==0 disconnects the VBAT pin (e.g. to save battery) #define LP 5 //Month register (TIME_REG+5) leap year bit //Alarm Control Bits #define ALMPOL 7 //Alarm Polarity: Defines the logic level for the MFP when an alarm is triggered. #define ALMC2 6 //Alarm configuration bits determine how alarms match. See ALM_MATCH defines below. #define ALMC1 5 #define ALMC0 4 #define ALMIF 3 //Alarm Interrupt Flag: Set by hardware when an alarm was triggered, cleared by software. enum {ALM_MATCH_SECONDS, ALM_MATCH_MINUTES, ALM_MATCH_HOURS, ALM_MATCH_DAY, ALM_MATCH_DATE, ALM_RESERVED_5, ALM_RESERVED_6, ALM_MATCH_DATETIME, ALM_DISABLE}; //Note ALM_MATCH_DAY triggers alarm at midnight #define ALARM_0 0 //constants for calling functions #define ALARM_1 1 class MCP79412RTC { public: MCP79412RTC(); static time_t get(void); static void set(time_t t); static void read(tmElements_t &tm); static void write(tmElements_t &tm); void sramWrite(byte addr, byte value); void sramWrite(byte addr, byte *values, byte nBytes); byte sramRead(byte addr); void sramRead(byte addr, byte *values, byte nBytes); void eepromWrite(byte addr, byte value); void eepromWrite(byte addr, byte *values, byte nBytes); byte eepromRead(byte addr); void eepromRead(byte addr, byte *values, byte nBytes); int calibRead(void); void calibWrite(int value); void idRead(byte *uniqueID); boolean powerFail(time_t *powerDown, time_t *powerUp); void squareWave(uint8_t freq); void setAlarm(uint8_t alarmNumber, time_t alarmTime); void enableAlarm(uint8_t alarmNumber, uint8_t alarmType); boolean alarm(uint8_t alarmNumber); void out(boolean level); void alarmPolarity(boolean polarity); boolean isRunning(void); private: static void ramWrite(byte addr, byte value); static void ramWrite(byte addr, byte *values, byte nBytes); static byte ramRead(byte addr); static void ramRead(byte addr, byte *values, byte nBytes); static byte eepromWait(void); static uint8_t dec2bcd(uint8_t num); static uint8_t bcd2dec(uint8_t num); }; extern MCP79412RTC RTC; #endif MCP79412RTC-1.0/ReadMe.txt000066400000000000000000000365311202446474100146630ustar00rootroot00000000000000ReadMe file for Arduino MCP79412 Library v1.0 https://github.com/JChristensen/MCP79412 Jack Christensen Sep 2012 This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. ================================================================================ Arduino library to support the Microchip MCP79412 Real-Time Clock. This library is intended for use with the Arduino Time.h library, http://www.arduino.cc/playground/Code/Time. The MCP79412 library is a drop-in replacement for the DS1307RTC.h library by Michael Margolis that is supplied with the Arduino Time library above. To change from using a DS1307 RTC to an MCP79412 RTC, it is only necessary to change the #include statement to include MCP79412RTC.h instead of DS1307RTC.h. This library also implements functions to support the additional features of the MCP79412. -------------------------------------------------------------------------------- To use the library: (1) Go to https://github.com/JChristensen/MCP79412/downloads and download the file in the compressed format of your choice (zip or tar.gz) to a convenient location on your PC. (2) Uncompress the downloaded file. This will result in a folder containing all the files for the library, that has a name similar to "JChristensen- MCP79412-42e98a7". (3) Rename the folder to just "MCP79412". (4) Copy the renamed folder to the Arduino sketchbook\libraries folder. -------------------------------------------------------------------------------- The following example sketches are included with the Timezone library: rtcSet1: Set the RTC date and time using a hard-coded value in the sketch. rtcSet2: Similar to rtcSet1, a different way to hard-code the date and time. rtcSet3: Set the RTC to the sketch compile date and time. rtcSetSerial: Set the RTC via serial input from the Arduino monitor. TimeRTC: Same as the example of the same name provided with the Time library, demonstrating the interchangeability of the MCP79412RTC library with the DS1307RTC library. PowerOutageLogger: A comprehensive example that implements a power failure logger using the MCP79412RTC's ability to capture power down and power up times. Power failure events are logged to the MCP79412RTC's SRAM. Output is to the Arduino serial monitor. -------------------------------------------------------------------------------- Similar to the DS1307RTC library, the MCP79412 library instantiates an RTC object; the user does not need to do this. To use the MCP79412 library, the Time and Wire libraries must also be included. For brevity, these includes are not repeated in the examples below: #include //http://github.com/JChristensen/MCP79412RTC #include //http://www.arduino.cc/playground/Code/Time #include //http://arduino.cc/en/Reference/Wire //(Wire.h is included with Arduino IDE) ================================================================================ SETTING AND READING THE TIME -------------------------------------------------------------------------------- The get() method reads the current time from the RTC and returns it as a time_t value. time_t myTime; myTime = RTC.get(); -------------------------------------------------------------------------------- The set(time_t t) method sets the RTC to the given time_t value. The example below first sets the system time (maintained by the Time library) to a hard-coded date and time, then sets the RTC from the system time. The setTime(hr, min, sec, day, month, year) function comes from the Time library. setTime(23, 31, 30, 13, 2, 2009); //set the system time to //23h31m30s on 3Feb2009 RTC.set(now()); //set the RTC from the system time -------------------------------------------------------------------------------- The read(tmElements_t &tm) method reads the current time from the RTC and returns it as a tmElements_t structure. (See the Arduino Time library for details on the tmElements_t structure: http://www.arduino.cc/playground/Code/Time.) tmElements_t tm; RTC.read(tm); Serial.print(tm.Hour, DEC); Serial.print(':'); Serial.print(tm.Minute,DEC); Serial.print(':'); Serial.println(tm.Second,DEC); -------------------------------------------------------------------------------- The write(tmElements_t &tm) method sets the RTC to the date and time as represented in a tmElements_t structure. tmElements_t tm; tm.Hour = 23; //set the tm structure to 23h31m30s on 13Feb2009 tm.Minute = 31; tm.Minute = 30; tm.Day = 13; tm.Month = 2; tm.Year = 2009 - 1970; //tmElements_t.Year is the offset from 1970. RTC.write(tm); //set the RTC from the tm structure -------------------------------------------------------------------------------- The isRunning() method returns a boolean value (true or false) indicating whether the RTC's oscillator is running. When there is no backup battery present, the RTC will reset when it is next powered up, and the oscillator will not be running. Setting the time starts the oscillator. if ( RTC.isRunning() ) //do something else //do something else ================================================================================ READING AND WRITING STATIC RAM (SRAM) The MCP79412 RTC has 64 bytes of battery-backed SRAM that can be read and written with the following methods using addresses between 0 and 63. Addresses passed to these functions are constrained to the valid range by an AND function. -------------------------------------------------------------------------------- sramWrite(byte addr, byte value) writes a single byte to the SRAM. RTC.sramWrite(3, 14); //write the value 14 to SRAM address 3 -------------------------------------------------------------------------------- sramWrite(byte addr, byte *values, byte nBytes) writes multiple bytes to consecutive SRAM locations. nBytes must be between 1 and 31. Invalid values of nBytes, or combinations of addr and nBytes that would result in addressing past the last byte of SRAM will result in no action. //write 1, 2, ..., 8 to the first eight SRAM locations byte buf[8] = {1, 2, 3, 4, 5, 6, 7, 8}; RTC.sramWrite(0, buf, 8); -------------------------------------------------------------------------------- sramRead(byte addr) reads a single byte from SRAM and returns the value. byte val; val = RTC.sramRead(3); //read the value from SRAM location 3 -------------------------------------------------------------------------------- sramRead(byte addr, byte *values, byte nBytes) reads multiple bytes from consecutive SRAM locations. nBytes must be between 1 and 32. Invalid values of nBytes, or combinations of addr and nBytes that would result in addressing past the last byte of SRAM will result in no action. //read the last eight locations of SRAM into buf byte buf[8]; RTC.sramRead(56, buf, 8); ================================================================================ READING AND WRITING EEPROM The MCP79412 RTC has 128 bytes of non-volatile EEPROM that can be read and written with the following methods using addresses between 0 and 127. Addresses passed to these functions are constrained to the valid range by an AND function. EEPROM is paged memory with a page size of 8 bytes; when writing multiple bytes, this this limits the number of bytes that can be written to 8. Page writes must start on a page boundary. -------------------------------------------------------------------------------- eepromWrite(byte addr, byte value) writes a single byte to EEPROM. RTC.eepromWrite(42, 55); //write the value 55 to EEPROM address 42 -------------------------------------------------------------------------------- eepromWrite(byte addr, byte *values, byte nBytes) writes a page (8 bytes) or less to EEPROM. addr should be a page start address (0, 8, ..., 120), but if not, is ruthlessly coerced into a valid value with an AND function. nBytes must be between 1 and 8, other values result in no action. //write 1, 2, ..., 8 to the first eight EEPROM locations byte buf[8] = {1, 2, 3, 4, 5, 6, 7, 8}; RTC.eepromWrite(0, buf, 8); -------------------------------------------------------------------------------- eepromRead(byte addr) reads a single byte from EEPROM and returns the value. byte val; val = RTC.eepromRead(42); //read the value from EEPROM location 42 -------------------------------------------------------------------------------- eepromRead(byte addr, byte *values, byte nBytes) reads multiple bytes from consecutive EEPROM locations. nBytes must be between 1 and 32. Invalid values of nBytes, or combinations of addr and nBytes that would result in addressing past the last byte of EEPROM will result in no action. //read the last eight locations of EEPROM into buf byte buf[8]; RTC.eepromRead(120, buf, 8); ================================================================================ ALARM FUNCTIONS The MCP79412 RTC has two alarms (Alarm-0 and Alarm-1) that can be used separately or simultaneously. When an alarm is triggered, a flag is set in the RTC that can be detected with the alarm() function below. Optionally, the RTC's Multi-Function Pin (MFP) can be driven to either a low or high logic level when an alarm is triggered. When using the MFP with both alarms, be sure to read the comments on the alarmPolarity function below. -------------------------------------------------------------------------------- setAlarm(uint8_t alarmNumber, time_t alarmTime) sets an alarm date and time. This sets the alarm registers only, it does not enable the alarm, this is done using the enableAlarm() function. alarmNumber is 0 or 1, but is ruthlessly masked to ensure a valid value. Note that depending on the alarm type chosen (see enableAlarm() below), only selected date or time parts may act as alarm critera. Nevertheless, valid values should be specified in the alarmTime parameter. //set alarm-1 for 30 seconds after midnight on 21Dec2012 tmElements_t tm; tm.Hour = 0; tm.Minute = 0; tm.Second = 30; tm.Year = CalendarYrToTm(2012); tm.Month = 12; tm.Day = 21; RTC.setAlarm(ALARM_1, makeTime(tm)); -------------------------------------------------------------------------------- enableAlarm(uint8_t alarmNumber, uint8_t alarmType) enable or disable the given alarm (0 or 1). alarmNumber is masked to ensure a value of 0 or 1. alarmType is one of the following: ALM_MATCH_SECONDS, ALM_MATCH_MINUTES, ALM_MATCH_HOURS, ALM_MATCH_DAY, ALM_MATCH_DATE, ALM_MATCH_DATETIME, ALM_DISABLE. //disable alarm-0 RTC.enableAlarm(ALARM_0, ALM_DISABLE); //enable alarm-1 to trigger when the minutes match. //assuming alarm-1 is set as in the example above, this will trigger the //alarm every hour, on the hour (minutes=0). RTC.enableAlarm(ALARM_1, ALM_MATCH_MINUTES); //enable alarm-1 to trigger when the seconds match. //assuming alarm-1 is set as in the example above, this will trigger the //alarm once a minute, at 30 seconds past the minute. RTC.enableAlarm(ALARM_1, ALM_MATCH_SECONDS); -------------------------------------------------------------------------------- alarm(uint8_t alarmNumber) tests whether the given alarm (0 or 1) has been triggered, and returns a corresponding boolean value (true or false). Clears the alarm flag to ensure that the next trigger event can be trapped. if ( RTC.alarm(ALARM_0) ) //alarm-0 has triggered else //alarm-0 has not triggered -------------------------------------------------------------------------------- alarmPolarity(boolean polarity) specifies the logic level on the Multi-Function Pin (MFP) when an alarm is triggered. The default is LOW. When both alarms are active, the two are ORed together to determine the level of the MFP. With alarm polarity set to LOW (the default), this causes the MFP to go low only when BOTH alarms are triggered. With alarm polarity set to HIGH, the MFP will go high when EITHER alarm is triggered. Note that the state of the MFP is independent of the alarm "interrupt" flags, and the alarm() function will indicate when an alarm is triggered regardless of the polarity. RTC.alarmPolarity(HIGH); //drives MFP high when an alarm is triggered ================================================================================ CALIBRATION, POWER FAILURE DETECTION, AND MISCELLANEOUS FUNCTIONS -------------------------------------------------------------------------------- calibWrite(int value) writes the given value to the RTC calibration register. This is an adjustment factor in PPM, and must be between -127 and 127. RTC.calibWrite(13); //makes the RTC run faster by 13 parts per million. RTC.calibWrite(-42); //makes the RTC run slower by 42 parts per million. -------------------------------------------------------------------------------- calibRead(void) returns the value of the RTC calibration register. int value; value = RTC.calibRead(); -------------------------------------------------------------------------------- powerFail(time_t *powerDown, time_t *powerUp) returns a boolean value (true or false) to indicate whether a power failure has occurred. If one occurred, the power down and power up timestamps are returned in the variables given by the caller, the RTC's power fail flag is reset and the power up/down timestamps are cleared. Note that the power down and power up timestamp registers do not contain values for seconds or for the year. The returned time stamps will therefore contain the current year from the RTC. However, there is a chance that a power outage spans from one year to the next. If this occurs, the power down timestamp would appear to be at a later time than the power up timestamp; if this is encountered, powerFail() will subtract one year from the power down timestamp before returning it. Still, there is an assumption that the timestamps are being read in the same year as that when the power up occurred. Finally, note that once the RTC records a power outage, it must be cleared before another can be recorded. If two power outages occur before powerFail() is called again, the time stamps for the earlier outage will be returned. time_t powerDown, powerUp; //power outage timestamps if ( RTC.powerFail(&powerDown, &powerUp) ) { //do something else //do something else -------------------------------------------------------------------------------- squareWave(uint8_t freq) enables or disables the square wave output on the multi-function pin (MFP). freq is one of the following: SQWAVE_1_HZ, SQWAVE_4096_HZ, SQWAVE_8192_HZ, SQWAVE_32768_HZ, SQWAVE_NONE RTC.squareWave(SQWAVE_1_HZ); //output a 1Hz square wave on the MFP -------------------------------------------------------------------------------- out(boolean level) sets the logic level on the MFP when it's not being used as a square wave or alarm output. The default value after an RTC chip reset is HIGH. RTC.out(LOW); //set the MFP to a low logic level -------------------------------------------------------------------------------- idRead(byte *uniqueID) returns the 64-bit unique ID from the RTC into the given 8-byte array. byte buf[8]; RTC.idRead(buf);