tmp102

In this article we look at the TMP102 digital sensor and we will connect it up to an ESP32

Layout

esp32 and tmp102

Parts List

Name	Link
ESP32		Aliexpress link Amazon Ebay
TMP102 breakout		Aliexpress link Ebay link Amazon Link
Connecting cables		Aliexpress link Amazon Ebay

Code

This code example originally comes from the Arduino site with a few tweaks

#include "Wire.h"
#define TMP102_I2C_ADDRESS 72 /* This is the I2C address for our chip. This value is correct if you tie the ADD0 pin to ground. See the datasheet for some other values. */


void setup() 
{
  Wire.begin(); // start the I2C library
  Serial.begin(115200); //Start serial communication at 115200 baud
}


void loop() 
{
  getTemp102();
  delay(5000); //wait 5 seconds before printing our next set of readings. 
}

void getTemp102()
{
  byte firstbyte, secondbyte; //these are the bytes we read from the TMP102 temperature registers
  int val; /* an int is capable of storing two bytes, this is where we "chuck" the two bytes together. */ 
  float convertedtemp; /* We then need to multiply our two bytes by a scaling factor, mentioned in the datasheet. */ 
  float correctedtemp; 

  /* Reset the register pointer (by default it is ready to read temperatures)
You can alter it to a writeable register and alter some of the configuration - 
the sensor is capable of alerting you if the temperature is above or below a specified threshold. */

  Wire.beginTransmission(TMP102_I2C_ADDRESS); //Say hi to the sensor. 
  Wire.write(0x00);
  Wire.endTransmission();
  Wire.requestFrom(TMP102_I2C_ADDRESS, 2);
  Wire.endTransmission();


  firstbyte      = (Wire.read()); 
  /*read the TMP102 datasheet - here we read one byte from
   each of the temperature registers on the TMP102*/
  secondbyte     = (Wire.read()); 
  /*The first byte contains the most significant bits, and 
   the second the less significant */
    val = firstbyte;
    if ((firstbyte & 0x80) > 0) 
    {
      val |= 0x0F00;
    } 
    val <<= 4; 
 /* MSB */
    val |= (secondbyte >> 4);    
/* LSB is ORed into the second 4 bits of our byte.
Bitwise maths is a bit funky, but there's a good tutorial on the playground*/
    convertedtemp = val*0.0625;
    correctedtemp = convertedtemp - 5; 
    /* See the above note on overreading */


  Serial.print("firstbyte is ");
  Serial.print("\t");
  Serial.println(firstbyte, BIN);
  Serial.print("secondbyte is ");
  Serial.print("\t");
  Serial.println(secondbyte, BIN);
  Serial.print("Concatenated byte is ");
  Serial.print("\t");
  Serial.println(val, BIN);
  Serial.print("Converted temp is ");
  Serial.print("\t");
  Serial.println(val*0.0625);
  Serial.print("Corrected temp is ");
  Serial.print("\t");
  Serial.println(correctedtemp);
  Serial.println();
}

Output

Open the serial monitor window and you should see something like this

firstbyte is 11100
secondbyte is 11100000
Concatenated byte is 111001110
Converted temp is 28.87
Corrected temp is 23.87

firstbyte is 11101
secondbyte is 0
Concatenated byte is 111010000
Converted temp is 29.00
Corrected temp is 24.00

firstbyte is 11011
secondbyte is 11000000
Concatenated byte is 110111100
Converted temp is 27.75
Corrected temp is 22.75

Link

http://www.ti.com/lit/gpn/tmp102