LM75B

MBED library for LM75B I2C temperature sensors

Features

• Read temperature
• Set over temperature and hysteresis temperature
• Over temperature interrupt
• Full control over LM75B
• Multiple sensors on same I2C bus

Usage

Quick usage

Initialize LM75B:

LM75B lm75(<I2C_SDA>, <I2C_SCL>, <address>);

• I2C_SDA: pin on which the sda pin is connected. Must be on an I2C interface (e.g. PB_9)
• I2C_SCL: pin on which the scl pin is connected. Must be on an I2C interface (e.g. PB_8)
• address: last 3 bits of lm75b address (e.g. 0b00000001)

Initialize LM75B with interrupt:

LM75B lm75(<I2C_SDA>, <I2C_SCL>, <address>, <osPin>, <osISR>);

• I2C_SDA: pin on which the sda pin is connected. Must be on an I2C interface (e.g. PB_9)
• I2C_SCL: pin on which the scl pin is connected. Must be on an I2C interface (e.g. PB_8)
• address: last 3 bits of lm75b address (e.g. 0b00000001)
• osPin: pin on which the O.S. pin is connected (e.g. PC_8)
• osISR: address of isr that will be executed if temperature exceeds os-temperature and falls under hyst-temperature (e.g &osISR)

Set LM75B to default values:

lm75.init();

Sets sensor in comparator mode with an active low O.S. pin.
Disables shutdown mode

Get temperature:

lm75.getTemperature();

Returns the temperature as float

Set os-temperature:

lm75.setTemperatureOS(<temperature>);

• temperature float: sets the os-temperature

Set hyst-temperature:

lm75.setTemperatureHYST(<temperature>);

• temperature float: sets the hyst-temperature

Advanced usage

Set shutdown mode:

lm75.setShutdownMode(<shutdown>);

• shutdown bool: true if sensor should be in shutdown mode

Set comparator/interrupt mode:

lm75.setCmpIntMode(<cmpMode>);

• cmpMode bool: true if sensor should be in comparator mode

Set os polarity:

lm75.setOSPolarity(<activeLow>);

• activeLow bool: true if O.S. pin should be in active low

Set os polarity:

lm75.getFaultQueue();

Returns the faults as int

Get os-temperature:

lm75.getTemperatureOS();

Returns the os-temperature as float

Get hyst-temperature:

lm75.getTemperatureHYST();

Returns the hyst-temperature as float

Enable O.S. IRQ:

lm.enableIRQ();

enables the O.S. pin interrupt

Disable O.S. IRQ:

lm.disableIRQ();

disables the O.S. pin interrupt

Temperature response diagram

Notes

• Tested on NUCLEO-L152RE (STM32)
• The temperature is measured and read in 0.5 °C steps
• The os/hyst-temperature can also be set in 0.5 °C steps
• OS-temperature is at power up at 80 °C
• HYST-temperature is at power up at 75 °C
• In shutdown mode all registers can be written and read
• Interrupt in this library uses comparator mode and calls ISR on falling and rising edges of O.S. pin
• When using interrupt mode on O.S. pin, you need to read from the sensor to reset the O.S. signal, otherwise it will remain in the current state forever (see LM75b datasheet)