LM95235 Arduino Library

This is a simple Arduino library for interfacing to TI's LM95235 ±0.75°C remote & local temperature sensor. The remote temperature sensor is useful for accurately providing cold junction compensation for a thermocouple measurement.

https://github.com/OneGneissGuy/LM95235

Methods

Constructor LM95235(I2C_address)

• Description: Constructor for the LM95235 device.

• Parameters: 7-bit I2C address

• Returns: None

• Example:

  #define LM95235_addr 0x18 //A0 tied to ground
  LM95235 lmtemp = LM95235(LM95235_addr);

begin()

• Description: Wraps Wire.begin().
• Parameters: None
• Returns: None
• Example: lmtemp.begin();

configure()

• Description: Initializes anything ... it does a reset.
• Parameters: None
• Returns: None
• Example: lmtemp.configure();

get_remote_temperature()

• Description: Read the temperature of the remote device.
• Parameters: None
• Returns: float temperature in celcius with resolution determined by filter CFG2_REMOTE_FILTER_EN/CFG2_REMOTE_FILTER_DIS status (On/EN=0.03125 C, off/DIS = 0.125 C)
• Example:

  float remote_temperature = lmtemp.get_remote_temperature()

Examples

You can find examples in the examples folder of this library.

Version History

0.1 initial commit

Packaging

Just zip up all the contents a .zip or download this repository as a .zip from GitHub.

Using library

In Arduino IDE menu, go to Sketch -> Include Libray -> Add ZIP Library.

After including it, you can add the include headers to your current sketch with Sketch -> Include Library -> LM95235.

Running examples

You can open the example from the Arduino IDE by going to the menu File -> Examples -> LM95235 -> readRemoteTemperature.

More Information

The LM95235 is an 11-bit digital temperature sensor with a 2-wire SMBus/I2C interface and TruTherm technology that can monitor the temperature of a remote diode as well as its own temperature.The LM95235 can be used to very accurately monitor the temperature of external devices or a diode-connected MMBT3904 transistor.

More info is available on the products website and the datasheet.

Device Registers

Register assignment	Register Address	Description	Register name
LM95235_REG_RW_CONFIG1	0x03		Configuration Register 1
LM95235_REG_RW_CONVERS_RATE	0x04		Conversion Rate
LM95235_REG_W_ONE_SHOT	0x0F		One-Shot
LM95235_REG_RW_CONFIG2	0xBF		Configuration Register 2
LM95235_REG_RW_REMOTE_OFFH	0x11		Remote Offset High Byte
LM95235_REG_RW_REMOTE_OFFL	0x12		Remote Offset Low Byte
LM95235_REG_R_STATUS1	0x02		Status Register 1
LM95235_REG_R_STATUS2	0x33		Status Register 2
LM95235_REG_RW_REMOTE_OS_LIMIT	0x07		Remote OS Limit
LM95235_REG_RW_LOCAL_OS_TCRIT_LIMIT	0x20		Local Shared OS and T_Crit Limit
LM95235_REG_RW_REMOTE_TCRIT_LIMIT	0x19		Remote T_Crit Limit
LM95235_REG_RW_COMMON_HYSTERESIS	0x21		Common Hysteresis
LM95235_REG_R_LOCAL_TEMPH_S	0x00		Local Temp MSB
LM95235_REG_R_LOCAL_TEMPL_S	0x30		Local Temp LSB
LM95235_REG_R_REMOTE_TEMPH_S	0x01		Remote Temp MSB – Signed
LM95235_REG_R_REMOTE_TEMPL_S	0x10		Remote Temp LSB – Signed
LM95235_REG_R_REMOTE_TEMPH_U	0x31		Remote Temp MSB – Unsigned
LM95235_REG_R_REMOTE_TEMPL_U	0x32		Remote Temp LSB – Unsigned
LM95235_REG_R_MAN_ID	0xFE		Manufacturer ID
LM95235_REG_R_CHIP_ID	0xFF		Revision ID

Device Specific bitfields

Configuration Register 1

Register assignment	Bit field Address	Description
CFG_STOP	0x40
CFG_REMOTE_TCRIT_MASK	0x10
CFG_REMOTE_OS_MASK	0x08
CFG_LOCAL_TCRIT_MASK	0x04
CFG_LOCAL_OS_MASK	0x02

Configuration Register 2

Register assignment	Bit field Address	Description
CFG2_OS_A0	0x40
CFG2_DIODE_FAULT_OS	0x20
CFG2_DIODE_FAULT_TCRIT	0x10
CFG2_REMOTE_TT	0x08
CFG2_REMOTE_FILTER_DIS	0x00
CFG2_REMOTE_FILTER_EN	0x06

Conversion Rate Register

Register assignment	Bit field Address	Description
RATE_CR0063	0x00
RATE_CR0364	0x01
RATE_CR1000	0x02
RATE_CR2500	0x03

Status Register 1

Register assignment	Bit field Address	Description	Register name
STATUS1_ROS	0x10
STATUS1_DIODE_FAULT	0x04
STATUS1_RTCRIT	0x02
STATUS1_LOC	0x01

IDENTIFICATION REGISTERS

Register assignment	Bit field Address	Description	Register name
MANUFACTURER_ID	0x01		Manufacturers ID Register
LM95235_REVISION	0xB1		Revision ID Register

Pinout

Pin Number	Pin Name	Type	Description
1	VDD	Power	Device power supply. Add bypass capacitor of 10 μF, 0.1 μF and 100 pF. Place 100 pF closest to device pin.
2	D+	Analog Input/Output	Positive input from the thermal diode.
3	D-	Analog Input/Output	Negative input from the thermal diode.
4	T_CRIT	Digital Output	Critical temperature output. Open-drain output requires pull-up resistor. Active low.
5	GND	Ground	Device ground.
6	OS/A0	Digital Input/Output	Address input. Can be tied to VDD, GND, or VDD/2.
7	SMBDAT	Digital Input/Output	SMBus/I2C interface data pin. Open-drain output requires pull-up resistor (e.g. 4.7 kOhm).
8	SMBCLK	Digital Input	SMBus/I2C interface clock pin. Open-drain output requires pull-up resistor (e.g. 4.7 kOhm).

Programmable I2C address

Pin Name	Setting	I2C Address
OS/A0	GND	0x18
OS/A0	VDD/2	0x29
OS/A0	VDD	0x4C

Wiring Schematic