Overview

• Name: LM75A
• Description: Library for LM75A temperature sensor
• Author: Gavin Lyons
• Developed on
  1. Raspberry pi PICO RP2040
  2. SDK C++ compiler G++ for arm-none-eabi
  3. CMAKE , VScode
• Ported from STM32 library

Features

This is a library for TI LM75A Digital Temperature Sensor and Thermal Watchdog With Two-Wire Interface Temperature Sensor I2C.

1. Shutdown Mode to Minimize Power Consumption
2. Up to Eight LM75As can be Connected to a Single Bus
3. Power up Defaults Permit Stand-Alone Operation
4. Supply Voltage /* LM75A: 2.7 V to 5.5 V
5. Supply Current
   • Operating: 280 μA (Typical)
   • Shutdown: 4 μA (Typical)
6. Temperature Accuracy
   • 25°C to 100°C: ±2°C (Max)
   • 55°C to 125°C: ±3°C (Max)
7. I2C 2 wire 400Khz

The LM75A provides 9-bit digital temperature readings . The LM75A has a dedicated over-temperature output (O.S.) with programmable limit and hysteresis. This output has programmable fault tolerance, which lets the user to define the number of consecutive error conditions that must occur before O.S. is activated. Shutdown low current mode included.

Power up mode:

• Comparator mode
• Tos = 80 °C
• Thyst = 75 °C
• OS active low

Pin 3 is the OS (overtemperature shutdown). It can be used to to trigger a pin interrupt. Set the functional mode, Tos and Thyst: if that functionally desired.

Connections

The Sensor uses I2C for communication's, data is outputted to a PC. Pins and I2C port(I2C0 or I2C1) can be set in the main.cpp. Default is I2C0 and GPIO16(data) GPIO17(clock).

Files

The main.cpp contains tests showing library functions There is also the library files(LM75A.cpp and LM75A.hpp),

Output

Data is outputted to the PC. Switch between the two routines modes by changing define statement in main.cpp Can also be toggled between Celsius and Fahrenheit.

1. Basic Usage
2. Library test routine

Datasheet

LM75A data sheets.

• Texas Instruments data sheet