Crate lm75

source ·
Expand description

This is a platform agnostic Rust driver for the LM75 temperature sensor and thermal watchdog, based on the embedded-hal traits.

This driver allows you to:

  • Enable/disable the device.
  • Read the temperature.
  • Set the fault queue.
  • Set the OS temperature.
  • Set the hysteresis temperature.
  • Set the OS operation mode.
  • Set the OS polarity.
  • Set the sample rate of temperature measurements (PCT2075 only)

The device

The LM75 temperature sensor includes a delta-sigma analog-to-digital converter, and a digital overtemperature detector. The host can query the LM75 through its I2C interface to read temperature at any time. The open-drain overtemperature output (OS) sinks current when the programmable temperature limit is exceeded. The OS output operates in either of two modes, comparator or interrupt. The host controls the temperature at which the alarm is asserted (TOS) and the hysteresis temperature below which the alarm condition is not valid (THYST). Also, the LM75’s TOS and THYST registers can be read by the host. The address of the LM75 is set with three pins to allow multiple devices to work on the same bus. Power-up is in comparator mode, with defaults of TOS= +80ºC and THYST= +75ºC. The 3.0V to 5.5V supply voltage range, low supply current, and I2C interface make the LM75 ideal for many applications in thermal management and protection.

Datasheet:

This driver is also compatible with at least LM75A, LM75B, LM75C, AT30TS75A, DS1775, DS75, DS7505, G751, MAX7500/1/2/3/4, MAX6625, MCP9800/1/2/3, STDS75, TCN75, PCT2075.

Usage examples (see also examples folder)

To use this driver, import this crate and an embedded_hal implementation, then instantiate the device.

Please find additional examples using hardware in this repository: driver-examples

Read temperature

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let address = Address::default();
let mut sensor = Lm75::new(dev, address);
let temp_celsius = sensor.read_temperature().unwrap();
println!("Temperature: {}ºC", temp_celsius);

Provide an alternative address

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let (a2, a1, a0) = (false, false, true);
let address = Address::from((a2,a1,a0));
let mut sensor = Lm75::new(dev, address);

Provide a full custom address

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let all_pins_floating = 0x37; // PCT2075 supports 27 addresses
let address = Address::from(all_pins_floating);
let mut sensor = Lm75::new_pct2075(dev, address);

Set the fault queue

This is the number of consecutive faults necessary to trigger an OS condition.

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address, FaultQueue};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let mut sensor = Lm75::new(dev, Address::default());
sensor.set_fault_queue(FaultQueue::_4).unwrap();

Set the OS polarity

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address, OsPolarity};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let mut sensor = Lm75::new(dev, Address::default());
sensor.set_os_polarity(OsPolarity::ActiveHigh).unwrap();

Set the OS operation mode

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address, OsMode};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let mut sensor = Lm75::new(dev, Address::default());
sensor.set_os_mode(OsMode::Interrupt).unwrap();

Set the OS temperature

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let mut sensor = Lm75::new(dev, Address::default());
let temp_celsius = 50.0;
sensor.set_os_temperature(temp_celsius).unwrap();

Set the hysteresis temperature

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let mut sensor = Lm75::new(dev, Address::default());
let temp_celsius = 40.0;
sensor.set_hysteresis_temperature(temp_celsius).unwrap();

Set the Sample Rate (PCT2075 only)

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let mut sensor = Lm75::new_pct2075(dev, Address::default());
let period = 1500; // in milliseconds, max = 3100, default 100
sensor.set_sample_rate(period).unwrap();

Enable / disable the sensor

use linux_embedded_hal::I2cdev;
use lm75::{Lm75, Address};

let dev = I2cdev::new("/dev/i2c-1").unwrap();
let mut sensor = Lm75::new(dev, Address::default());
sensor.disable().unwrap(); // shutdown
sensor.enable().unwrap();

Modules

Structs

Enums