Kevin Braun / ds3232m

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

ds3232m.cpp@2:a9a8027a7cb2, 2014-12-25 (annotated)

Committer:
loopsva
Date:
Thu Dec 25 21:38:22 2014 +0000
Revision:
2:a9a8027a7cb2
Parent:
1:0975d4a9b513
Child:
3:e9c5025ba2ca
Child:
6:968b8efe3ca0
Removed all RTOS contingency.  Put all RTOS Mutex I2C lock/unlock back on the calling program.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
loopsva 0:30a7faf58768 1 #include "mbed.h"
loopsva 0:30a7faf58768 2 #include "ds3232m.h"
loopsva 0:30a7faf58768 3
loopsva 0:30a7faf58768 4 #define RTCI2CADDRESS 0xd0
loopsva 0:30a7faf58768 5 #define DS3232SECONDS 0x00
loopsva 0:30a7faf58768 6 #define DS3232DAYOFWEEK 0x03
loopsva 0:30a7faf58768 7 #define DS3232ALM1BOTTOM 0x07
loopsva 0:30a7faf58768 8 #define DS3232ALM2BOTTOM 0x0b
loopsva 0:30a7faf58768 9 #define DS3232CTLREG 0x0e
loopsva 0:30a7faf58768 10 #define DS3232STATREG 0x0f
loopsva 0:30a7faf58768 11 #define DS3232TEMPERATURE 0x11
loopsva 0:30a7faf58768 12 #define DS3232TESTREG 0x13
loopsva 0:30a7faf58768 13 #define DS3232RAMBOTTOM 0x14
loopsva 0:30a7faf58768 14 #define DS3232RAMCRC16 0xfe
loopsva 0:30a7faf58768 15 //control register
loopsva 0:30a7faf58768 16 #define DS3232_EOSCN_BIT 0x80 //turn on/off oscillator in batt backup mode, 0 = on
loopsva 0:30a7faf58768 17 #define DS3232_BBSQW_BIT 0x40 //battery backed 1Hz enable, 1 = enable
loopsva 0:30a7faf58768 18 #define DS3232_CONV_BIT 0x20 //start temperature conversion, 1 = start
loopsva 0:30a7faf58768 19 #define DS3232_INTCN_BIT 0x04 //interrupt control, 1 = interrupt mode, 0 = 1Hz mode
loopsva 0:30a7faf58768 20 //status register
loopsva 0:30a7faf58768 21 #define DS3232_OSF_BIT 0x80 //oscillator stopped, 1 = stopped
loopsva 0:30a7faf58768 22 #define DS3232_BB32KHZ_BIT 0x40 //battery backed 32KHz enable, 1 = enable(writable bit)
loopsva 0:30a7faf58768 23 #define DS3232_EN32KHZ_BIT 0x08 //32KHz enable, 1 = enable(writable bit)
loopsva 0:30a7faf58768 24 #define DS3232_BUSY_BIT 0x04 //busy doing a temperature A:D conversion, 1 = busy
loopsva 0:30a7faf58768 25
loopsva 0:30a7faf58768 26 char RtcCtlReg = 0;
loopsva 0:30a7faf58768 27 char RtcStatReg = 0;
loopsva 0:30a7faf58768 28
loopsva 0:30a7faf58768 29 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 30 // constructor with fixed frequency
loopsva 0:30a7faf58768 31
loopsva 0:30a7faf58768 32 ds3232m::ds3232m(PinName sda, PinName scl) {
loopsva 0:30a7faf58768 33 // Create a new I2C object
loopsva 0:30a7faf58768 34 _i2c_ = new I2C(sda, scl);
loopsva 0:30a7faf58768 35 // Set the frequency to standard 400kHz
loopsva 0:30a7faf58768 36 _i2c_->frequency(400000);
loopsva 0:30a7faf58768 37 }
loopsva 0:30a7faf58768 38
loopsva 0:30a7faf58768 39 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 40 // constructor with I2C frequency selection
loopsva 0:30a7faf58768 41
loopsva 0:30a7faf58768 42 ds3232m::ds3232m(PinName sda, PinName scl, int i2cFrequency) {
loopsva 0:30a7faf58768 43 _i2c_ = new I2C(sda, scl);
loopsva 0:30a7faf58768 44 _i2c_->frequency(i2cFrequency);
loopsva 0:30a7faf58768 45 }
loopsva 0:30a7faf58768 46
loopsva 0:30a7faf58768 47 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 48 // deconstructor
loopsva 0:30a7faf58768 49
loopsva 0:30a7faf58768 50 ds3232m::~ds3232m() {
loopsva 0:30a7faf58768 51 }
loopsva 0:30a7faf58768 52
loopsva 0:30a7faf58768 53 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 54 // set time up into the DS3232M
loopsva 0:30a7faf58768 55
loopsva 0:30a7faf58768 56 void ds3232m::setTime(Time_rtc& time) {
loopsva 0:30a7faf58768 57 char buffer[7];
loopsva 0:30a7faf58768 58 buffer[0] = DecToBCD(time.sec);
loopsva 0:30a7faf58768 59 buffer[1] = DecToBCD(time.min);
loopsva 0:30a7faf58768 60 buffer[2] = DecToBCD(time.hour);
loopsva 0:30a7faf58768 61 buffer[3] = time.wday;
loopsva 0:30a7faf58768 62 buffer[4] = DecToBCD(time.date);
loopsva 0:30a7faf58768 63 buffer[5] = DecToBCD(time.mon);
loopsva 0:30a7faf58768 64 buffer[6] = DecToBCD(time.year - 2000);
loopsva 2:a9a8027a7cb2 65
loopsva 0:30a7faf58768 66 _i2c_->start();
loopsva 0:30a7faf58768 67 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 68 _i2c_->write(DS3232SECONDS);
loopsva 0:30a7faf58768 69 for(int i = 0; i < 7; i++) _i2c_->write(buffer[i]);
loopsva 0:30a7faf58768 70 _i2c_->stop();
loopsva 0:30a7faf58768 71 }
loopsva 0:30a7faf58768 72
loopsva 0:30a7faf58768 73 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 74 // get time from the DS3232M and stick it into the mbed's RTC
loopsva 0:30a7faf58768 75
loopsva 0:30a7faf58768 76 void ds3232m::getTime(Time_rtc& time) {
loopsva 0:30a7faf58768 77 char buffer[7];
loopsva 0:30a7faf58768 78 _i2c_->start();
loopsva 0:30a7faf58768 79 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 80 _i2c_->write(DS3232SECONDS);
loopsva 0:30a7faf58768 81 _i2c_->start();
loopsva 0:30a7faf58768 82 _i2c_->write(RTCI2CADDRESS + 1);
loopsva 0:30a7faf58768 83 for(int i = 0; i < 7; i++) buffer[i] = _i2c_->read(1);
loopsva 0:30a7faf58768 84 int rtcgarbage = (_i2c_->read(0)); //final junk read
loopsva 0:30a7faf58768 85 _i2c_->stop();
loopsva 0:30a7faf58768 86
loopsva 0:30a7faf58768 87 time.sec = BCDToDec(buffer[0]);
loopsva 0:30a7faf58768 88 time.min = BCDToDec(buffer[1]);
loopsva 0:30a7faf58768 89 time.hour = ds3232m::BCDToDec(buffer[2]);
loopsva 0:30a7faf58768 90 time.wday = buffer[3];
loopsva 0:30a7faf58768 91 time.date = ds3232m::BCDToDec(buffer[4]);
loopsva 0:30a7faf58768 92 time.mon = ds3232m::BCDToDec(buffer[5]);
loopsva 0:30a7faf58768 93 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
loopsva 0:30a7faf58768 94 }
loopsva 0:30a7faf58768 95
loopsva 0:30a7faf58768 96 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 97 // retrieve the control and status registers
loopsva 0:30a7faf58768 98
loopsva 0:30a7faf58768 99 void ds3232m::getControlStatusRegs() {
loopsva 0:30a7faf58768 100 _i2c_->start();
loopsva 0:30a7faf58768 101 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 102 _i2c_->write(DS3232CTLREG);
loopsva 0:30a7faf58768 103 _i2c_->start();
loopsva 0:30a7faf58768 104 _i2c_->write(RTCI2CADDRESS + 1);
loopsva 0:30a7faf58768 105 RtcCtlReg = _i2c_->read(1);
loopsva 0:30a7faf58768 106 RtcStatReg = _i2c_->read(0);
loopsva 0:30a7faf58768 107 _i2c_->stop();
loopsva 0:30a7faf58768 108 }
loopsva 0:30a7faf58768 109
loopsva 0:30a7faf58768 110 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 111 // enables/disables the main oscillator during battery backup mode. true = enable during battery backup mode
loopsva 0:30a7faf58768 112
loopsva 0:30a7faf58768 113 void ds3232m::enableBattClock(bool batt) {
loopsva 0:30a7faf58768 114 getControlStatusRegs();
loopsva 0:30a7faf58768 115 if(batt == true) {
loopsva 0:30a7faf58768 116 RtcCtlReg &= ~DS3232_EOSCN_BIT;
loopsva 0:30a7faf58768 117 } else {
loopsva 0:30a7faf58768 118 RtcCtlReg |= DS3232_EOSCN_BIT;
loopsva 0:30a7faf58768 119 }
loopsva 2:a9a8027a7cb2 120
loopsva 0:30a7faf58768 121 _i2c_->start();
loopsva 0:30a7faf58768 122 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 123 _i2c_->write(DS3232CTLREG);
loopsva 0:30a7faf58768 124 _i2c_->write(RtcCtlReg);
loopsva 0:30a7faf58768 125 _i2c_->stop();
loopsva 0:30a7faf58768 126 }
loopsva 0:30a7faf58768 127
loopsva 0:30a7faf58768 128 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 129 // check to see if DS3232M's temperature conversion cycle is bust or not
loopsva 0:30a7faf58768 130 // only 1 per second max
loopsva 0:30a7faf58768 131
loopsva 0:30a7faf58768 132 bool ds3232m::checkTempBusy() {
loopsva 0:30a7faf58768 133 getControlStatusRegs();
loopsva 0:30a7faf58768 134 if(RtcCtlReg & DS3232_CONV_BIT) return true; //is already busy
loopsva 0:30a7faf58768 135 if(RtcStatReg & DS3232_BUSY_BIT) return true; //is already busy
loopsva 0:30a7faf58768 136 return false;
loopsva 0:30a7faf58768 137 }
loopsva 0:30a7faf58768 138
loopsva 0:30a7faf58768 139 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 140 // start a temperature conversion cycle
loopsva 0:30a7faf58768 141 // only 1 per second max
loopsva 0:30a7faf58768 142
loopsva 0:30a7faf58768 143 bool ds3232m::startTempCycle() {
loopsva 0:30a7faf58768 144 getControlStatusRegs();
loopsva 0:30a7faf58768 145 if((checkTempBusy()) == true) return false; //is already busy
loopsva 0:30a7faf58768 146 RtcCtlReg |= DS3232_CONV_BIT;
loopsva 2:a9a8027a7cb2 147
loopsva 0:30a7faf58768 148 _i2c_->start();
loopsva 0:30a7faf58768 149 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 150 _i2c_->write(DS3232CTLREG);
loopsva 0:30a7faf58768 151 _i2c_->write(RtcCtlReg);
loopsva 0:30a7faf58768 152 _i2c_->stop();
loopsva 0:30a7faf58768 153 return true;
loopsva 0:30a7faf58768 154 }
loopsva 0:30a7faf58768 155
loopsva 0:30a7faf58768 156 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 157 // get temperature
loopsva 0:30a7faf58768 158 // if returned value = 255.0, then temperature conversion was still busy
loopsva 0:30a7faf58768 159
loopsva 0:30a7faf58768 160 float ds3232m::getTemperature() {
loopsva 0:30a7faf58768 161 getControlStatusRegs();
loopsva 0:30a7faf58768 162 if((checkTempBusy()) == false) return(255.0); //is already busy
loopsva 2:a9a8027a7cb2 163
loopsva 0:30a7faf58768 164 _i2c_->start();
loopsva 0:30a7faf58768 165 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 166 _i2c_->write(DS3232TEMPERATURE);
loopsva 0:30a7faf58768 167 _i2c_->start();
loopsva 0:30a7faf58768 168 _i2c_->write(RTCI2CADDRESS + 1);
loopsva 0:30a7faf58768 169 int8_t temp3232a = (_i2c_->read(1));
loopsva 0:30a7faf58768 170 uint8_t temp3232b = _i2c_->read(0);
loopsva 0:30a7faf58768 171 _i2c_->stop();
loopsva 1:0975d4a9b513 172
loopsva 0:30a7faf58768 173 float temp3232 = float(temp3232a);
loopsva 0:30a7faf58768 174 //for positive temp
loopsva 0:30a7faf58768 175 if((temp3232b == 0x40) && (temp3232a >= 0)) temp3232 += 0.25;
loopsva 0:30a7faf58768 176 if (temp3232b == 0x80) temp3232 += 0.5;
loopsva 0:30a7faf58768 177 if((temp3232b == 0xc0) && (temp3232a >= 0)) temp3232 += 0.75;
loopsva 0:30a7faf58768 178 //for negative temp
loopsva 0:30a7faf58768 179 if((temp3232b == 0x40) && (temp3232a < 0)) temp3232 += 0.75;
loopsva 0:30a7faf58768 180 if((temp3232b == 0xc0) && (temp3232a < 0)) temp3232 += 0.25;
loopsva 0:30a7faf58768 181 return (temp3232);
loopsva 0:30a7faf58768 182 }
loopsva 0:30a7faf58768 183
loopsva 0:30a7faf58768 184 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 185 // get seconds register
loopsva 0:30a7faf58768 186
loopsva 0:30a7faf58768 187 int ds3232m::getSeconds() {
loopsva 0:30a7faf58768 188 _i2c_->start();
loopsva 0:30a7faf58768 189 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 190 _i2c_->write(DS3232SECONDS);
loopsva 0:30a7faf58768 191 _i2c_->start();
loopsva 0:30a7faf58768 192 _i2c_->write(RTCI2CADDRESS + 1);
loopsva 0:30a7faf58768 193 int seconds3232 = (_i2c_->read(0));
loopsva 0:30a7faf58768 194 _i2c_->stop();
loopsva 2:a9a8027a7cb2 195
loopsva 0:30a7faf58768 196 int xbcd = BCDToDec(seconds3232);
loopsva 0:30a7faf58768 197 return(xbcd);
loopsva 0:30a7faf58768 198 }
loopsva 0:30a7faf58768 199
loopsva 0:30a7faf58768 200 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 201 // clears all user memory inside the DS3232M. Top 2 locations - reserved for CRC, also set to 00 since CRC value is 0x00 0x00
loopsva 0:30a7faf58768 202
loopsva 0:30a7faf58768 203 void ds3232m::clearRAM() {
loopsva 0:30a7faf58768 204 _i2c_->start();
loopsva 0:30a7faf58768 205 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 206 _i2c_->write(DS3232RAMBOTTOM);
loopsva 0:30a7faf58768 207 for(int i = DS3232RAMBOTTOM; i < 256; i++) _i2c_->write(NULL);
loopsva 0:30a7faf58768 208 _i2c_->stop();
loopsva 0:30a7faf58768 209 }
loopsva 0:30a7faf58768 210
loopsva 0:30a7faf58768 211 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 212 // retrieves user data from DS3232M RAM
loopsva 0:30a7faf58768 213 // returns 00 = ok
loopsva 0:30a7faf58768 214 // returns 01 = length + offset is over the highest user RAM location
loopsva 0:30a7faf58768 215 // returns 02 = offset < 0x14
loopsva 0:30a7faf58768 216 // returns 04 = length = 0
loopsva 0:30a7faf58768 217 // returns 08 = crc error
loopsva 0:30a7faf58768 218
loopsva 0:30a7faf58768 219 int ds3232m::getUserRAM(char *buffer, int offset, int length) {
loopsva 0:30a7faf58768 220 if((offset + length) > 0xfe) return(1);
loopsva 0:30a7faf58768 221 if(offset < 0x14) return(2);
loopsva 0:30a7faf58768 222 if(length == 0) return(4);
loopsva 2:a9a8027a7cb2 223
loopsva 0:30a7faf58768 224 _i2c_->start();
loopsva 0:30a7faf58768 225 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 226 _i2c_->write(offset);
loopsva 0:30a7faf58768 227 _i2c_->start();
loopsva 0:30a7faf58768 228 _i2c_->write(RTCI2CADDRESS + 1);
loopsva 0:30a7faf58768 229 for(int i = 0; i < length; i++) buffer[i] = _i2c_->read(1);
loopsva 0:30a7faf58768 230 _i2c_->read(0);
loopsva 0:30a7faf58768 231 _i2c_->stop();
loopsva 2:a9a8027a7cb2 232
loopsva 0:30a7faf58768 233 if(LoadRTCRam() == false) return(8);
loopsva 0:30a7faf58768 234 return(0);
loopsva 0:30a7faf58768 235 }
loopsva 0:30a7faf58768 236
loopsva 0:30a7faf58768 237 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 238 // puts user data into DS3232M RAM. CRC16 value added to the top 2 RAM location
loopsva 0:30a7faf58768 239 // returns 00 = ok
loopsva 0:30a7faf58768 240 // returns 01 = length + offset is over the highest user RAM location
loopsva 0:30a7faf58768 241 // returns 02 = offset < 0x14
loopsva 0:30a7faf58768 242 // returns 04 = length = 0
loopsva 0:30a7faf58768 243
loopsva 0:30a7faf58768 244 int ds3232m::putUserRAM(char *buffer, int offset, int length) {
loopsva 0:30a7faf58768 245 if((offset + length) > 0xfe) return(1);
loopsva 0:30a7faf58768 246 if(offset < 0x14) return(2);
loopsva 0:30a7faf58768 247 if(length == 0) return(4);
loopsva 2:a9a8027a7cb2 248
loopsva 0:30a7faf58768 249 _i2c_->start();
loopsva 0:30a7faf58768 250 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 251 _i2c_->write(offset);
loopsva 0:30a7faf58768 252 for(int i = 0; i < length; i++) _i2c_->write(buffer[i]);
loopsva 0:30a7faf58768 253 _i2c_->stop();
loopsva 2:a9a8027a7cb2 254
loopsva 0:30a7faf58768 255 addCRC16();
loopsva 0:30a7faf58768 256 return(0);
loopsva 0:30a7faf58768 257 }
loopsva 0:30a7faf58768 258
loopsva 0:30a7faf58768 259 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 260 // enable/disable 32KHz output with run on battery mode option
loopsva 0:30a7faf58768 261
loopsva 0:30a7faf58768 262 void ds3232m::set32KhzOutput(bool ena, bool batt) {
loopsva 0:30a7faf58768 263 getControlStatusRegs();
loopsva 0:30a7faf58768 264 if(ena == true) {
loopsva 0:30a7faf58768 265 RtcStatReg |= DS3232_EN32KHZ_BIT;
loopsva 0:30a7faf58768 266 if(batt == true) {
loopsva 0:30a7faf58768 267 RtcStatReg |= DS3232_BB32KHZ_BIT;
loopsva 0:30a7faf58768 268 } else {
loopsva 0:30a7faf58768 269 RtcStatReg &= ~DS3232_BB32KHZ_BIT;
loopsva 0:30a7faf58768 270 }
loopsva 0:30a7faf58768 271 } else {
loopsva 0:30a7faf58768 272 RtcStatReg &= ~DS3232_EN32KHZ_BIT;
loopsva 0:30a7faf58768 273 RtcStatReg &= ~DS3232_BB32KHZ_BIT;
loopsva 0:30a7faf58768 274 }
loopsva 2:a9a8027a7cb2 275
loopsva 0:30a7faf58768 276 _i2c_->start();
loopsva 0:30a7faf58768 277 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 278 _i2c_->write(DS3232STATREG);
loopsva 0:30a7faf58768 279 _i2c_->write(RtcStatReg);
loopsva 0:30a7faf58768 280 _i2c_->stop();
loopsva 0:30a7faf58768 281 }
loopsva 0:30a7faf58768 282
loopsva 0:30a7faf58768 283 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 284 // enable/disable 1Hz output with run on battery mode option
loopsva 0:30a7faf58768 285
loopsva 0:30a7faf58768 286 void ds3232m::set1hzOutput(bool ena, bool batt) {
loopsva 0:30a7faf58768 287 getControlStatusRegs();
loopsva 0:30a7faf58768 288 if(ena == true) {
loopsva 0:30a7faf58768 289 RtcCtlReg &= ~DS3232_INTCN_BIT;
loopsva 0:30a7faf58768 290 if(batt == true) {
loopsva 0:30a7faf58768 291 RtcCtlReg |= DS3232_BBSQW_BIT;
loopsva 0:30a7faf58768 292 } else {
loopsva 0:30a7faf58768 293 RtcCtlReg &= ~DS3232_BBSQW_BIT;
loopsva 0:30a7faf58768 294 }
loopsva 0:30a7faf58768 295 } else {
loopsva 0:30a7faf58768 296 RtcCtlReg |= DS3232_INTCN_BIT;
loopsva 0:30a7faf58768 297 RtcCtlReg &= ~DS3232_BBSQW_BIT;
loopsva 0:30a7faf58768 298 }
loopsva 2:a9a8027a7cb2 299
loopsva 0:30a7faf58768 300 _i2c_->start();
loopsva 0:30a7faf58768 301 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 302 _i2c_->write(DS3232CTLREG);
loopsva 0:30a7faf58768 303 _i2c_->write(RtcCtlReg);
loopsva 0:30a7faf58768 304 _i2c_->stop();
loopsva 0:30a7faf58768 305 }
loopsva 0:30a7faf58768 306
loopsva 0:30a7faf58768 307 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 308 // CRC table and routine taken from Emilie Laverge's CRC16 library
loopsva 0:30a7faf58768 309 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 310 // lookup table for calculating crc16
loopsva 0:30a7faf58768 311
loopsva 0:30a7faf58768 312 uint16_t crc16table[256] = {
loopsva 0:30a7faf58768 313 0x0000, 0x8005, 0x800F, 0x000A, 0x801B, 0x001E, 0x0014, 0x8011,
loopsva 0:30a7faf58768 314 0x8033, 0x0036, 0x003C, 0x8039, 0x0028, 0x802D, 0x8027, 0x0022,
loopsva 0:30a7faf58768 315 0x8063, 0x0066, 0x006C, 0x8069, 0x0078, 0x807D, 0x8077, 0x0072,
loopsva 0:30a7faf58768 316 0x0050, 0x8055, 0x805F, 0x005A, 0x804B, 0x004E, 0x0044, 0x8041,
loopsva 0:30a7faf58768 317 0x80C3, 0x00C6, 0x00CC, 0x80C9, 0x00D8, 0x80DD, 0x80D7, 0x00D2,
loopsva 0:30a7faf58768 318 0x00F0, 0x80F5, 0x80FF, 0x00FA, 0x80EB, 0x00EE, 0x00E4, 0x80E1,
loopsva 0:30a7faf58768 319 0x00A0, 0x80A5, 0x80AF, 0x00AA, 0x80BB, 0x00BE, 0x00B4, 0x80B1,
loopsva 0:30a7faf58768 320 0x8093, 0x0096, 0x009C, 0x8099, 0x0088, 0x808D, 0x8087, 0x0082,
loopsva 0:30a7faf58768 321 0x8183, 0x0186, 0x018C, 0x8189, 0x0198, 0x819D, 0x8197, 0x0192,
loopsva 0:30a7faf58768 322 0x01B0, 0x81B5, 0x81BF, 0x01BA, 0x81AB, 0x01AE, 0x01A4, 0x81A1,
loopsva 0:30a7faf58768 323 0x01E0, 0x81E5, 0x81EF, 0x01EA, 0x81FB, 0x01FE, 0x01F4, 0x81F1,
loopsva 0:30a7faf58768 324 0x81D3, 0x01D6, 0x01DC, 0x81D9, 0x01C8, 0x81CD, 0x81C7, 0x01C2,
loopsva 0:30a7faf58768 325 0x0140, 0x8145, 0x814F, 0x014A, 0x815B, 0x015E, 0x0154, 0x8151,
loopsva 0:30a7faf58768 326 0x8173, 0x0176, 0x017C, 0x8179, 0x0168, 0x816D, 0x8167, 0x0162,
loopsva 0:30a7faf58768 327 0x8123, 0x0126, 0x012C, 0x8129, 0x0138, 0x813D, 0x8137, 0x0132,
loopsva 0:30a7faf58768 328 0x0110, 0x8115, 0x811F, 0x011A, 0x810B, 0x010E, 0x0104, 0x8101,
loopsva 0:30a7faf58768 329 0x8303, 0x0306, 0x030C, 0x8309, 0x0318, 0x831D, 0x8317, 0x0312,
loopsva 0:30a7faf58768 330 0x0330, 0x8335, 0x833F, 0x033A, 0x832B, 0x032E, 0x0324, 0x8321,
loopsva 0:30a7faf58768 331 0x0360, 0x8365, 0x836F, 0x036A, 0x837B, 0x037E, 0x0374, 0x8371,
loopsva 0:30a7faf58768 332 0x8353, 0x0356, 0x035C, 0x8359, 0x0348, 0x834D, 0x8347, 0x0342,
loopsva 0:30a7faf58768 333 0x03C0, 0x83C5, 0x83CF, 0x03CA, 0x83DB, 0x03DE, 0x03D4, 0x83D1,
loopsva 0:30a7faf58768 334 0x83F3, 0x03F6, 0x03FC, 0x83F9, 0x03E8, 0x83ED, 0x83E7, 0x03E2,
loopsva 0:30a7faf58768 335 0x83A3, 0x03A6, 0x03AC, 0x83A9, 0x03B8, 0x83BD, 0x83B7, 0x03B2,
loopsva 0:30a7faf58768 336 0x0390, 0x8395, 0x839F, 0x039A, 0x838B, 0x038E, 0x0384, 0x8381,
loopsva 0:30a7faf58768 337 0x0280, 0x8285, 0x828F, 0x028A, 0x829B, 0x029E, 0x0294, 0x8291,
loopsva 0:30a7faf58768 338 0x82B3, 0x02B6, 0x02BC, 0x82B9, 0x02A8, 0x82AD, 0x82A7, 0x02A2,
loopsva 0:30a7faf58768 339 0x82E3, 0x02E6, 0x02EC, 0x82E9, 0x02F8, 0x82FD, 0x82F7, 0x02F2,
loopsva 0:30a7faf58768 340 0x02D0, 0x82D5, 0x82DF, 0x02DA, 0x82CB, 0x02CE, 0x02C4, 0x82C1,
loopsva 0:30a7faf58768 341 0x8243, 0x0246, 0x024C, 0x8249, 0x0258, 0x825D, 0x8257, 0x0252,
loopsva 0:30a7faf58768 342 0x0270, 0x8275, 0x827F, 0x027A, 0x826B, 0x026E, 0x0264, 0x8261,
loopsva 0:30a7faf58768 343 0x0220, 0x8225, 0x822F, 0x022A, 0x823B, 0x023E, 0x0234, 0x8231,
loopsva 0:30a7faf58768 344 0x8213, 0x0216, 0x021C, 0x8219, 0x0208, 0x820D, 0x8207, 0x0202
loopsva 0:30a7faf58768 345 };
loopsva 0:30a7faf58768 346
loopsva 0:30a7faf58768 347 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 348 // calculate a crc value for the DS3232M user ram area. CRC value calculated from address 0x14 - 0xfd
loopsva 0:30a7faf58768 349
loopsva 0:30a7faf58768 350 uint16_t ds3232m::calculateCRC16(char input[], int offset, int length) {
loopsva 0:30a7faf58768 351 uint16_t CRC16s = 0;
loopsva 0:30a7faf58768 352 input+= offset;
loopsva 0:30a7faf58768 353 for(int i = offset; i < (length + offset); i++) {
loopsva 0:30a7faf58768 354 uint16_t tableValue = crc16table[((CRC16s >> 8) ^ *(char *)input++) & 0x00ff];
loopsva 0:30a7faf58768 355 CRC16s = (CRC16s << 8) ^ tableValue;
loopsva 0:30a7faf58768 356 }
loopsva 0:30a7faf58768 357 return CRC16s;
loopsva 0:30a7faf58768 358 }
loopsva 0:30a7faf58768 359
loopsva 0:30a7faf58768 360 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 361 // This function gets the entire contents of the RTC. Returns flase if a CRC error occured
loopsva 0:30a7faf58768 362
loopsva 0:30a7faf58768 363 char RTCbuffer[256];
loopsva 0:30a7faf58768 364
loopsva 0:30a7faf58768 365 bool ds3232m::LoadRTCRam() {
loopsva 0:30a7faf58768 366 _i2c_->start();
loopsva 0:30a7faf58768 367 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 368 _i2c_->write(0x00);
loopsva 0:30a7faf58768 369 _i2c_->start();
loopsva 0:30a7faf58768 370 _i2c_->write(RTCI2CADDRESS + 1);
loopsva 0:30a7faf58768 371 int i = 0;
loopsva 0:30a7faf58768 372 for(i = 0; i < 255; i++) {
loopsva 0:30a7faf58768 373 RTCbuffer[i] = _i2c_->read(1);
loopsva 0:30a7faf58768 374 }
loopsva 0:30a7faf58768 375 RTCbuffer[i] = _i2c_->read(0);
loopsva 0:30a7faf58768 376 _i2c_->stop();
loopsva 2:a9a8027a7cb2 377
loopsva 0:30a7faf58768 378 uint16_t calcdCRC = calculateCRC16(RTCbuffer, DS3232RAMBOTTOM, (DS3232RAMCRC16 - DS3232RAMBOTTOM));
loopsva 2:a9a8027a7cb2 379
loopsva 0:30a7faf58768 380 _i2c_->start();
loopsva 0:30a7faf58768 381 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 382 _i2c_->write(DS3232RAMCRC16);
loopsva 0:30a7faf58768 383 _i2c_->start();
loopsva 0:30a7faf58768 384 _i2c_->write(RTCI2CADDRESS + 1);
loopsva 0:30a7faf58768 385 uint16_t storedCRC = (_i2c_->read(1) << 8) + (_i2c_->read(0) & 0xff);
loopsva 0:30a7faf58768 386 _i2c_->stop();
loopsva 2:a9a8027a7cb2 387
loopsva 0:30a7faf58768 388 if(storedCRC != calcdCRC) return false;
loopsva 0:30a7faf58768 389 return true;
loopsva 0:30a7faf58768 390 }
loopsva 0:30a7faf58768 391
loopsva 0:30a7faf58768 392 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:30a7faf58768 393 // This function calculates and saves CRC data to the end of RTC's RAM.
loopsva 0:30a7faf58768 394 // CRC calculated address range is 0x14 - 0xfd. CRC data is placed in 0xfe and 0xff
loopsva 0:30a7faf58768 395
loopsva 0:30a7faf58768 396 void ds3232m::addCRC16() {
loopsva 0:30a7faf58768 397 LoadRTCRam();
loopsva 0:30a7faf58768 398 uint16_t resultCRC = calculateCRC16(RTCbuffer, DS3232RAMBOTTOM, (DS3232RAMCRC16 - DS3232RAMBOTTOM)); //0x14 is offset from 0 in buffer, 230 is length //
loopsva 2:a9a8027a7cb2 399
loopsva 0:30a7faf58768 400 _i2c_->start();
loopsva 0:30a7faf58768 401 _i2c_->write(RTCI2CADDRESS);
loopsva 0:30a7faf58768 402 _i2c_->write(DS3232RAMCRC16);
loopsva 0:30a7faf58768 403 _i2c_->write(resultCRC >> 8);
loopsva 0:30a7faf58768 404 _i2c_->write(resultCRC & 0xff);
loopsva 0:30a7faf58768 405 _i2c_->stop();
loopsva 0:30a7faf58768 406 }
loopsva 1:0975d4a9b513 407