Using DS1820 data as integers--Solved (3 ways)

Other Hardware Sensors
1

I am using the DallasTemperature.h successfully, no complaints. However, there are a number of cases in my control software where I only need to use the integer value of the temperature, which would also allow me to store my 40 variables in a smaller index.

I noticed that if the 12-bit temperature is read as a two-byte integer, it could be shifted left 4 bits and the high byte would contain the integer of the temperature and the low byte would contain the fraction. This would also preserve the sign bit. I am only smart enough to use the function that returns the temperature as a float:

float mytemp1 ;
mytemp1 = sensors1.getTempCByIndex(0) ;

The DallasTemperature.h and DallasTemperature.cpp is a bit difficult to follow. Is there a function that returns the temperature as an integer, or is there a simple way to convert the floating value to a two-byte integer?

2

It will be automatically translated.
You can use the temperature in 1/100 degrees.

// integer 'x' will be 10.
float temperature = 10.95;
int x;
x = (int) temperature;

// y will be 1095;
int y;
y = (int) (temperature * 100.0);
3

I just use the OneWire library, it only takes a few lines of code to read the sensor. I also like to work in the integer domain to avoid the code size and run time overhead of floating point.

#include <OneWire.h>          //http://www.pjrc.com/teensy/td_libs_OneWire.html
#include <Streaming.h>        //http://arduiniana.org/libraries/streaming/

const int DS_PIN = 5;         //DS18B20 temperature sensor
OneWire ds(DS_PIN);

void setup(void)
{
    Serial.begin(115200);
}

void loop(void)
{
    dsStart();
    delay(1000);                //wait for temperature conversion to complete

    int C = dsReadC16();
    int F = dsReadF10();
    Serial << (C + 8) / 16 << "C " << (F + 5) / 10 << "F\n";

//    float C = dsReadC16() / 16.0;
//    float F = dsReadF10() / 10.0;
//    Serial << C << "C " << F << "F\n";
}

//start temperature conversion
void dsStart(void)
{
    ds.reset();
    ds.skip();
    ds.write(0x44);
}

//get temperature as °C times 16
int dsReadC16(void)
{
    uint8_t dsData[9];

    ds.reset();
    ds.skip();
    ds.write(0xBE);                //read scratchpad

    for ( int i=0; i<9; i++) {     //read 9 bytes
        dsData[i] = ds.read();
    }

    if (OneWire::crc8(dsData, 8) == dsData[8]) {
        return (dsData[1] << 8) + dsData[0];
    }
    else {
        return -9999; //CRC error
    }
}

//get temperature as °F * 10
int dsReadF10(void)
{
    long tC16 = dsReadC16();        //°C * 16
    if (tC16 == -9999) return tC16;
    long tF160 = tC16 * 18;         //°F * 160 but without the 32 degree offset
    int tF10 = tF160 / 16;          //°F * 10
    if (tF160 & 15 >= 8) tF10++;    //round up to the next tenth if needed (x & 15 is more efficient than x % 16)
    tF10 = tF10 + 320;              //add in the offset (*10)
    return tF10;
}
4

Sheepdog works fine and derives whole and frac. I guess you just use the whole. No libraries.