Using Lego temperature sensor with Arduino

Question

I have Arduino mega and Lego temperature sensor which I would like to connect to the Arduino. I'm trying to use a I2C connection between them, with no luck. I connected the sensor and Arduino referring to the picture below:wiring I'm using the Wire library for transmitting data. This is my code currently:

#include < Wire.h >
byte ADDRESS=0x98;
byte CONFIG=0x01;
void setup(){
 Serial.begin(9600);
 Wire.begin();
 Wire.beginTransmission(ADDRESS);
 Wire.write(CONFIG);
 Wire.endTransmission();
 delay(100);
}
void loop(){
 Wire.beginTransmission(ADDRESS);
 Wire.write(CONFIG);
 Wire.endTransmission();
 Wire.requestFrom(ADDRESS,2);
 delay(100);
 int avail=Wire.available();
 Serial.println(avail);
 delay(100);
}

I found the config and address values from RobotC drivers for the same sensor. But all I get is zeros. Is there any way i could check for a defect sensor? Is my code correct?

• Jot: Start with a i2c scanner : playground.arduino.cc/Main/I2cScanner
• Mazaryk: Looks like this is the datasheet for the actual sensor ti.com/lit/ds/symlink/tmp275.pdf. Reading that and cross referencing with the header file you liked to, should explain how to communicate with it.
• Samelikameli: I2C scanner helped me to use the correct address, which was different from the one in drivers. Now my sensor is working. Thank you, Jot!

Answer 1

I managed to get it work with the following code:

float getTemp(){
 #define ADDRESS 0x4C
 #define CONFIG 0x00
 float temp;
 Wire.beginTransmission(ADDRESS);
 Wire.write(CONFIG);
 Wire.endTransmission();
 delay(50);
 Wire.requestFrom(ADDRESS,2);
 temp=Wire.read();
 if(Wire.read()==128){
 temp+=0.5;
 }
 return temp;
}

And connect the green wire to 3.3V, not to the 5V.