Tested and working library for the DS1621 temperature sensor with I2C
Dependents: condato_Coldchainlogger condato_Coldchainlogger 039847382-S3_DS1621_and_LCD_V1
Diff: ds1621.cpp
- Revision:
- 0:20bfb7df0470
diff -r 000000000000 -r 20bfb7df0470 ds1621.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ds1621.cpp Fri Jul 06 20:51:31 2012 +0000 @@ -0,0 +1,142 @@ +#include "ds1621.h" + +DS1621::DS1621(I2C* _interface, unsigned char _address): i2c(_interface), address(_address) { + conversion_busy=false; + LastTemp=0.0; + StartConversion(false); + + printf("Searching for I2C devices...\n"); + + int count = 0; + for (int address=4; address<256; address+=2) { + if (!i2c->write(address, NULL, 0)) { // 0 returned is ok + printf(" - I2C device found at address 0x%02X\r\n", address); + count++; + } + } + printf("%d devices found\r\n", count); +} + +// Set configuration register +void DS1621::SetConfig(unsigned char cfg) { + char data[2]; + data[0]=ACCESS_CONFIG; + data[1]=cfg; + i2c->write(address,data,2); +} + +// Read a DS1621 register +unsigned char DS1621::ReadReg(unsigned char reg) { + char data[1]; + data[0]=reg; + i2c->write(address,data,1,true); + i2c->read(address,data,1); + return (data[0]); +} + +// Sets temperature limit +// -- works only with ACCESS_TL and ACCESS_TH +void DS1621::SetLimit(unsigned char reg, float temp) { + if (reg == ACCESS_TL || reg == ACCESS_TH) { + char data[3]; + data[0]=reg; + if (temp <0.0) { + temp = ceil(temp * 2.0 - 0.5) / 2.0; //round to 1/2 degree + if (floor(temp) < temp ) { // check for extra half + data[1]=(~char(temp * -1.0)); //one's complement + data[2]=0x80; // -25.5 = -26 + 0.5 + } else { + data[1]=(~char(temp * -1.0)) + 1; //two's complement + data[2]=0; // -25 = -25 + } + } else { + temp = floor(temp * 2.0 + 0.5) / 2.0; //round to 1/2 degree + data[1]=char(temp); //whole degrees + if (ceil(temp) > temp) { // check for extra half + data[2]=0x80; + } else { + data[2]=0x00; + } + } + i2c->write(address,data,3); + wait_ms(10); + } +} + +// Start/Stop DS1621 temperature conversion +void DS1621::StartConversion(bool start) { + char data[1]; + if (start == true) { + data[0]=START_CONVERT_T; + i2c->write(address,data,1); + } else { + data[0]=STOP_CONVERT_T; + i2c->write(address,data,1); + } +} + +// Reads temperature or threshold +// -- works only with READ_TEMPERATURE, ACCESS_TL, and ACCESS_TH +// -- DS1621 must be in continouis mode and started for the actual temperature +bool DS1621::GetTemp(unsigned char reg, float *Temp) { + unsigned char data[2]; + float Tc; + + if (reg == READ_TEMPERATURE || reg == ACCESS_TL || reg == ACCESS_TH) { + ReadChipTemp(reg,data); + + Tc=float(data[1]>>7) * 0.5; // decimal part = +0.5 if bit7=1 + + if (data[0] >= 0x80) { // negative? -> make two's complement + *Temp = float((char (~data[0])+1)*-1) + Tc; + } else { + *Temp = float(data[0])+ Tc; + } + return (true); + } + return (false); +} + +// Read high resolution temperature +// -- returns temperature in 1/100ths degrees +// -- DS1620 must be in 1-shot mode +bool DS1621::GetHResTemp(float *Temp) { + + if (conversion_busy==false) { + SetConfig(ONESHOT); + StartConversion(true); // initiate conversion + conversion_busy=true; + *Temp = LastTemp; + return (false); + } + + if (!(ReadReg(ACCESS_CONFIG) & DONE)) { + *Temp = LastTemp; + return (false); + } else { + unsigned char data[2]; + // get the results + ReadChipTemp(READ_TEMPERATURE,data); // get whole degrees reading + float cRem = (float)ReadReg(READ_COUNTER); // get counts remaining + float cSlope = (float)ReadReg(READ_SLOPE); // get counts per degree + if (data[0] >= 0x80) { // negative? -> make two's complement + LastTemp = float((char (~data[0])+1)*-1); + } else { + LastTemp = float(data[0]); + } + LastTemp = LastTemp - 0.25 + (cSlope - cRem)/cSlope; + conversion_busy=false; + *Temp = LastTemp; + return (true); + } + +} + +void DS1621::ReadChipTemp(unsigned char reg, unsigned char *data) { + if (reg == READ_TEMPERATURE || reg == ACCESS_TL || reg == ACCESS_TH) { + char cmd[1]; + cmd[0]=reg; + i2c->write(address,cmd,1,true); + i2c->read(address, (char *)data, 2); + } +} \ No newline at end of file