Library for Maxim DS3232M super-accurate, I2C based Real Time Clock chip with 234 bytes of user RAM. Library includes user RAM read/write operations along with CRC routines for accessing the user RAM area.
Dependents: ds3232m_HelloWorld
Diff: ds3232m.cpp
- Revision:
- 0:30a7faf58768
- Child:
- 1:0975d4a9b513
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ds3232m.cpp Mon Dec 08 20:15:16 2014 +0000 @@ -0,0 +1,391 @@ +#include "mbed.h" +#include "ds3232m.h" + +#define RTCI2CADDRESS 0xd0 +#define DS3232SECONDS 0x00 +#define DS3232DAYOFWEEK 0x03 +#define DS3232ALM1BOTTOM 0x07 +#define DS3232ALM2BOTTOM 0x0b +#define DS3232CTLREG 0x0e +#define DS3232STATREG 0x0f +#define DS3232TEMPERATURE 0x11 +#define DS3232TESTREG 0x13 +#define DS3232RAMBOTTOM 0x14 +#define DS3232RAMCRC16 0xfe +//control register +#define DS3232_EOSCN_BIT 0x80 //turn on/off oscillator in batt backup mode, 0 = on +#define DS3232_BBSQW_BIT 0x40 //battery backed 1Hz enable, 1 = enable +#define DS3232_CONV_BIT 0x20 //start temperature conversion, 1 = start +#define DS3232_INTCN_BIT 0x04 //interrupt control, 1 = interrupt mode, 0 = 1Hz mode +//status register +#define DS3232_OSF_BIT 0x80 //oscillator stopped, 1 = stopped +#define DS3232_BB32KHZ_BIT 0x40 //battery backed 32KHz enable, 1 = enable(writable bit) +#define DS3232_EN32KHZ_BIT 0x08 //32KHz enable, 1 = enable(writable bit) +#define DS3232_BUSY_BIT 0x04 //busy doing a temperature A:D conversion, 1 = busy + +char RtcCtlReg = 0; +char RtcStatReg = 0; + +//--------------------------------------------------------------------------------------------------------------------------------------// +// constructor with fixed frequency + +ds3232m::ds3232m(PinName sda, PinName scl) { + // Create a new I2C object + _i2c_ = new I2C(sda, scl); + // Set the frequency to standard 400kHz + _i2c_->frequency(400000); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// constructor with I2C frequency selection + +ds3232m::ds3232m(PinName sda, PinName scl, int i2cFrequency) { + _i2c_ = new I2C(sda, scl); + _i2c_->frequency(i2cFrequency); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// deconstructor + +ds3232m::~ds3232m() { +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// set time up into the DS3232M + +void ds3232m::setTime(Time_rtc& time) { + char buffer[7]; + buffer[0] = DecToBCD(time.sec); + buffer[1] = DecToBCD(time.min); + buffer[2] = DecToBCD(time.hour); + buffer[3] = time.wday; + buffer[4] = DecToBCD(time.date); + buffer[5] = DecToBCD(time.mon); + buffer[6] = DecToBCD(time.year - 2000); + + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232SECONDS); + for(int i = 0; i < 7; i++) _i2c_->write(buffer[i]); + _i2c_->stop(); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// get time from the DS3232M and stick it into the mbed's RTC + +void ds3232m::getTime(Time_rtc& time) { + char buffer[7]; + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232SECONDS); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS + 1); + for(int i = 0; i < 7; i++) buffer[i] = _i2c_->read(1); + int rtcgarbage = (_i2c_->read(0)); //final junk read + _i2c_->stop(); + + time.sec = BCDToDec(buffer[0]); + time.min = BCDToDec(buffer[1]); + time.hour = ds3232m::BCDToDec(buffer[2]); + time.wday = buffer[3]; + time.date = ds3232m::BCDToDec(buffer[4]); + time.mon = ds3232m::BCDToDec(buffer[5]); + time.year = ds3232m::BCDToDec(buffer[6]) + 2000; // plus hundred is because RTC is giving the years since 2000, but std c struct tm needs years since 1900 +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// retrieve the control and status registers + +void ds3232m::getControlStatusRegs() { + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232CTLREG); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS + 1); + RtcCtlReg = _i2c_->read(1); + RtcStatReg = _i2c_->read(0); + _i2c_->stop(); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// enables/disables the main oscillator during battery backup mode. true = enable during battery backup mode + +void ds3232m::enableBattClock(bool batt) { + getControlStatusRegs(); + if(batt == true) { + RtcCtlReg &= ~DS3232_EOSCN_BIT; + } else { + RtcCtlReg |= DS3232_EOSCN_BIT; + } + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232CTLREG); + _i2c_->write(RtcCtlReg); + _i2c_->stop(); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// check to see if DS3232M's temperature conversion cycle is bust or not +// only 1 per second max + +bool ds3232m::checkTempBusy() { + getControlStatusRegs(); + if(RtcCtlReg & DS3232_CONV_BIT) return true; //is already busy + if(RtcStatReg & DS3232_BUSY_BIT) return true; //is already busy + return false; +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// start a temperature conversion cycle +// only 1 per second max + +bool ds3232m::startTempCycle() { + getControlStatusRegs(); + if((checkTempBusy()) == true) return false; //is already busy + RtcCtlReg |= DS3232_CONV_BIT; + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232CTLREG); + _i2c_->write(RtcCtlReg); + _i2c_->stop(); + return true; +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// get temperature +// if returned value = 255.0, then temperature conversion was still busy + +float ds3232m::getTemperature() { + getControlStatusRegs(); + if((checkTempBusy()) == false) return(255.0); //is already busy + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232TEMPERATURE); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS + 1); + int8_t temp3232a = (_i2c_->read(1)); + uint8_t temp3232b = _i2c_->read(0); + _i2c_->stop(); + float temp3232 = float(temp3232a); + //for positive temp + if((temp3232b == 0x40) && (temp3232a >= 0)) temp3232 += 0.25; + if (temp3232b == 0x80) temp3232 += 0.5; + if((temp3232b == 0xc0) && (temp3232a >= 0)) temp3232 += 0.75; + //for negative temp + if((temp3232b == 0x40) && (temp3232a < 0)) temp3232 += 0.75; + if((temp3232b == 0xc0) && (temp3232a < 0)) temp3232 += 0.25; + return (temp3232); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// get seconds register + +int ds3232m::getSeconds() { + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232SECONDS); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS + 1); + int seconds3232 = (_i2c_->read(0)); + _i2c_->stop(); + int xbcd = BCDToDec(seconds3232); + return(xbcd); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// clears all user memory inside the DS3232M. Top 2 locations - reserved for CRC, also set to 00 since CRC value is 0x00 0x00 + +void ds3232m::clearRAM() { + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232RAMBOTTOM); + for(int i = DS3232RAMBOTTOM; i < 256; i++) _i2c_->write(NULL); + _i2c_->stop(); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// retrieves user data from DS3232M RAM +// returns 00 = ok +// returns 01 = length + offset is over the highest user RAM location +// returns 02 = offset < 0x14 +// returns 04 = length = 0 +// returns 08 = crc error + +int ds3232m::getUserRAM(char *buffer, int offset, int length) { + if((offset + length) > 0xfe) return(1); + if(offset < 0x14) return(2); + if(length == 0) return(4); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(offset); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS + 1); + for(int i = 0; i < length; i++) buffer[i] = _i2c_->read(1); + _i2c_->read(0); + _i2c_->stop(); + if(LoadRTCRam() == false) return(8); + return(0); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// puts user data into DS3232M RAM. CRC16 value added to the top 2 RAM location +// returns 00 = ok +// returns 01 = length + offset is over the highest user RAM location +// returns 02 = offset < 0x14 +// returns 04 = length = 0 + +int ds3232m::putUserRAM(char *buffer, int offset, int length) { + if((offset + length) > 0xfe) return(1); + if(offset < 0x14) return(2); + if(length == 0) return(4); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(offset); + for(int i = 0; i < length; i++) _i2c_->write(buffer[i]); + _i2c_->stop(); + addCRC16(); + return(0); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// enable/disable 32KHz output with run on battery mode option + +void ds3232m::set32KhzOutput(bool ena, bool batt) { + getControlStatusRegs(); + if(ena == true) { + RtcStatReg |= DS3232_EN32KHZ_BIT; + if(batt == true) { + RtcStatReg |= DS3232_BB32KHZ_BIT; + } else { + RtcStatReg &= ~DS3232_BB32KHZ_BIT; + } + } else { + RtcStatReg &= ~DS3232_EN32KHZ_BIT; + RtcStatReg &= ~DS3232_BB32KHZ_BIT; + } + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232STATREG); + _i2c_->write(RtcStatReg); + _i2c_->stop(); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// enable/disable 1Hz output with run on battery mode option + +void ds3232m::set1hzOutput(bool ena, bool batt) { + getControlStatusRegs(); + if(ena == true) { + RtcCtlReg &= ~DS3232_INTCN_BIT; + if(batt == true) { + RtcCtlReg |= DS3232_BBSQW_BIT; + } else { + RtcCtlReg &= ~DS3232_BBSQW_BIT; + } + } else { + RtcCtlReg |= DS3232_INTCN_BIT; + RtcCtlReg &= ~DS3232_BBSQW_BIT; + } + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232CTLREG); + _i2c_->write(RtcCtlReg); + _i2c_->stop(); +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// CRC table and routine taken from Emilie Laverge's CRC16 library +//--------------------------------------------------------------------------------------------------------------------------------------// +// lookup table for calculating crc16 + +uint16_t crc16table[256] = { + 0x0000, 0x8005, 0x800F, 0x000A, 0x801B, 0x001E, 0x0014, 0x8011, + 0x8033, 0x0036, 0x003C, 0x8039, 0x0028, 0x802D, 0x8027, 0x0022, + 0x8063, 0x0066, 0x006C, 0x8069, 0x0078, 0x807D, 0x8077, 0x0072, + 0x0050, 0x8055, 0x805F, 0x005A, 0x804B, 0x004E, 0x0044, 0x8041, + 0x80C3, 0x00C6, 0x00CC, 0x80C9, 0x00D8, 0x80DD, 0x80D7, 0x00D2, + 0x00F0, 0x80F5, 0x80FF, 0x00FA, 0x80EB, 0x00EE, 0x00E4, 0x80E1, + 0x00A0, 0x80A5, 0x80AF, 0x00AA, 0x80BB, 0x00BE, 0x00B4, 0x80B1, + 0x8093, 0x0096, 0x009C, 0x8099, 0x0088, 0x808D, 0x8087, 0x0082, + 0x8183, 0x0186, 0x018C, 0x8189, 0x0198, 0x819D, 0x8197, 0x0192, + 0x01B0, 0x81B5, 0x81BF, 0x01BA, 0x81AB, 0x01AE, 0x01A4, 0x81A1, + 0x01E0, 0x81E5, 0x81EF, 0x01EA, 0x81FB, 0x01FE, 0x01F4, 0x81F1, + 0x81D3, 0x01D6, 0x01DC, 0x81D9, 0x01C8, 0x81CD, 0x81C7, 0x01C2, + 0x0140, 0x8145, 0x814F, 0x014A, 0x815B, 0x015E, 0x0154, 0x8151, + 0x8173, 0x0176, 0x017C, 0x8179, 0x0168, 0x816D, 0x8167, 0x0162, + 0x8123, 0x0126, 0x012C, 0x8129, 0x0138, 0x813D, 0x8137, 0x0132, + 0x0110, 0x8115, 0x811F, 0x011A, 0x810B, 0x010E, 0x0104, 0x8101, + 0x8303, 0x0306, 0x030C, 0x8309, 0x0318, 0x831D, 0x8317, 0x0312, + 0x0330, 0x8335, 0x833F, 0x033A, 0x832B, 0x032E, 0x0324, 0x8321, + 0x0360, 0x8365, 0x836F, 0x036A, 0x837B, 0x037E, 0x0374, 0x8371, + 0x8353, 0x0356, 0x035C, 0x8359, 0x0348, 0x834D, 0x8347, 0x0342, + 0x03C0, 0x83C5, 0x83CF, 0x03CA, 0x83DB, 0x03DE, 0x03D4, 0x83D1, + 0x83F3, 0x03F6, 0x03FC, 0x83F9, 0x03E8, 0x83ED, 0x83E7, 0x03E2, + 0x83A3, 0x03A6, 0x03AC, 0x83A9, 0x03B8, 0x83BD, 0x83B7, 0x03B2, + 0x0390, 0x8395, 0x839F, 0x039A, 0x838B, 0x038E, 0x0384, 0x8381, + 0x0280, 0x8285, 0x828F, 0x028A, 0x829B, 0x029E, 0x0294, 0x8291, + 0x82B3, 0x02B6, 0x02BC, 0x82B9, 0x02A8, 0x82AD, 0x82A7, 0x02A2, + 0x82E3, 0x02E6, 0x02EC, 0x82E9, 0x02F8, 0x82FD, 0x82F7, 0x02F2, + 0x02D0, 0x82D5, 0x82DF, 0x02DA, 0x82CB, 0x02CE, 0x02C4, 0x82C1, + 0x8243, 0x0246, 0x024C, 0x8249, 0x0258, 0x825D, 0x8257, 0x0252, + 0x0270, 0x8275, 0x827F, 0x027A, 0x826B, 0x026E, 0x0264, 0x8261, + 0x0220, 0x8225, 0x822F, 0x022A, 0x823B, 0x023E, 0x0234, 0x8231, + 0x8213, 0x0216, 0x021C, 0x8219, 0x0208, 0x820D, 0x8207, 0x0202 +}; + +//--------------------------------------------------------------------------------------------------------------------------------------// +// calculate a crc value for the DS3232M user ram area. CRC value calculated from address 0x14 - 0xfd + +uint16_t ds3232m::calculateCRC16(char input[], int offset, int length) { + uint16_t CRC16s = 0; + input+= offset; + for(int i = offset; i < (length + offset); i++) { + uint16_t tableValue = crc16table[((CRC16s >> 8) ^ *(char *)input++) & 0x00ff]; + CRC16s = (CRC16s << 8) ^ tableValue; + } + return CRC16s; +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// This function gets the entire contents of the RTC. Returns flase if a CRC error occured + +char RTCbuffer[256]; + +bool ds3232m::LoadRTCRam() { + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(0x00); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS + 1); + int i = 0; + for(i = 0; i < 255; i++) { + RTCbuffer[i] = _i2c_->read(1); + } + RTCbuffer[i] = _i2c_->read(0); + _i2c_->stop(); + uint16_t calcdCRC = calculateCRC16(RTCbuffer, DS3232RAMBOTTOM, (DS3232RAMCRC16 - DS3232RAMBOTTOM)); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232RAMCRC16); + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS + 1); + uint16_t storedCRC = (_i2c_->read(1) << 8) + (_i2c_->read(0) & 0xff); + _i2c_->stop(); + if(storedCRC != calcdCRC) return false; + return true; +} + +//--------------------------------------------------------------------------------------------------------------------------------------// +// This function calculates and saves CRC data to the end of RTC's RAM. +// CRC calculated address range is 0x14 - 0xfd. CRC data is placed in 0xfe and 0xff + +void ds3232m::addCRC16() { + LoadRTCRam(); + uint16_t resultCRC = calculateCRC16(RTCbuffer, DS3232RAMBOTTOM, (DS3232RAMCRC16 - DS3232RAMBOTTOM)); //0x14 is offset from 0 in buffer, 230 is length // + _i2c_->start(); + _i2c_->write(RTCI2CADDRESS); + _i2c_->write(DS3232RAMCRC16); + _i2c_->write(resultCRC >> 8); + _i2c_->write(resultCRC & 0xff); + _i2c_->stop(); +}