LM75A-library

LM75A is a great value-size sensor IC with 0.5°C accuracy and Overtemperature Shutdown feature. It talks throught I2C protocol so its great for use with Arduino! That´s why i wrote this complete library with access to all of LM75A´s registers and functions. I´ve seen few libraries for this IC but none of them had ability to set OS mode or HYST temp.

Functions

You can find comments and more in header file and source code

LM75A(address)

Creates a new instance of LM75A class, takes 1 argument, and that is I2C address of device (default is 0x48)

LM75A tempSensor(0x48);

getTemp()

Returns measured temperature value as uint_16t (16bit unsigned int) in °C

int measured_temp = tempSensor.getTemp();

shutdown(enable)

Parameters:

• true (set IC to sleep mode)
• false (wake up IC from sleep mode)

tempSensor.shutdown(true);

setOSmode(mode)

Parameters:

• true (Interrupt mode, create an interrupt (short pulse for MCU) on OS pin (see datasheet))
• false (Comparator mode, stays at set value (by setOSpolarity) until temperature is lower than set)

tempSensor.setOSmode(true);

setOSpolarity(polarity)

Parameters:

• true (active HIGH, sets pin HIGH when OS happens
• false (active LOW, sets pin LOW when OS happens

tempSensor.setOSpolarity(true);

fault(queue)

Parameters:

• uint8_t queue (queue size, max readings before OS interrupt happens, available sizes: 1,2,4,6)

tempSensor.fault(2);

setOStemp(os_temp)

Parameters:

• uint8_t os_temp (Overtemperature Shutdown value, being constantly compared to measured value, is its greater or equal to this register, set an OS interrupt)

tempSensor.setOStemp(50);

setHYSTtemp(hyst_temp)

Parameters:

• uint8_t hyst_temp (Set hysteresis value (some kind of error rate tolerance, see datasheet (i got well by using same or +-1°C as in setOStemp())))

tempSensor.setHYSTtemp(50);

getOStemp()

For debugging purposes, returns content of OStemp register (to see if its set correctly)

int OStemp_content = tempSensor.getOStemp();

getHYSTtemp()

For debugging purposes, returns content of OShyst register (to see if its set correctly)

int OShyst_content = tempSensor.getHYtemp();

getTempF()

Returns measured temperature value as uint_16t but in °F

int tempF = tempSensor.getTempF();

Sample code

#include <LM75A.h>

LM75A sensor(0x48); //create instance of this library with name "sensor" and at address 0x48

void setup() {
  Serial.begin(9600); //begin Serial

  sensor.setOSmode(false);
  sensor.setOStemp(33); //set OS temp to 33°C (triggers a COMPARE output that we set)
  sensor.setHYSTtemp(32); //set hysteresis temp to 32°C to get rid of errors

  Serial.println(sensor.getOStemp()); //print content of OStemp register to see if its set correctly
  Serial.println(sensor.getHYSTtemp()); //print content of OShyst register to see if its set correctly
  Serial.println("-----");  //spacer
}

void loop() {
  Serial.println(sensor.getTemp()); //print measured temperature
  delay(1000);  //1s delay
}

Also, i tested every function of library and it worked BUT, if you have any problems be sure to create new issue!