Raspi-1wire-temp NPM

Raspberry Pi 1-Wire High-Level Interface

Provides a high-level interface to a "1-wire" compatible device or file on a Raspberry Pi.

This code was really only tested with a DS18B20 on a Raspberry Pi 3. I would very much appreciate testers with different hardware to test and use this module.

Installation

npm install raspi-1wire-temp

Usage

Finding Devices

The idea with this approach is for R1WT to automatically determine what type of temperature controller to create. Currently this project only supports the output from a DS18B20 device. However if/when more temperature sensors are tested they could be integrated into R1WT relatively easy.

const r1wt = require('raspi-1wire-temp');
const devices = r1wt.findDevices();

By default, R1WT looks for devices that can be globbed with /sys/bus/w1/devices/28-*/w1_slave. However, findDevices() method has an optional hint glob string that can help R1WT find the device files.

const r1wt = require('raspi-1wire-temp');
const devices = r1wt.findDevices('/dev/my/temp/sensor*.dev');

The findDevices() method will return a non-null array of filenames to devices.

Creating A Device Controller

Once you obtain the filename of a device, either through findDevices() or from a known location, the fromDevice() method is used to create the temperature controller.

const r1wt = require('raspi-1wire-temp');
const devices = r1wt.findDevices();
assert(devices.length > 0);

const controller = r1wt.fromDevice(devices[0]);
console.log(controller.current.celsius)
console.log(controller.current.fahrenheit)

For every call to controller.current the controller will re-read the device for the current temperature. If reading from the device is an expensive call it might be wise to cache the current temperature object for some time.

Create an Emulated Controller

For some contexts, like testing, you might need a stubbed or emulated device controller. The fromStream() method can be used to provide this functionality. This may be particularly useful when developing software on non-RPI hardware. Effectively allowing a temperature sensor to be emulated with a known stream of data.

const r1wt = require('raspi-1wire-temp');
const controller = r1wt.fromStream(false, 1000, 2000, 3000)

assert(controller.current.celsius == 1000);
assert(controller.current.celsius == 2000);
assert(controller.current.celsius == 3000);

The first argument to fromStream() is a flag indicating if the stream should repeat. When set to false the stream will raise an error when the data has been exhausted. To repeat the stream, set the flag to true.

const r1wt = require('raspi-1wire-temp');
const controller = r1wt.fromStream(true, 1000, 2000, 3000)

assert(controller.current.celsius == 1000);
assert(controller.current.celsius == 2000);
assert(controller.current.celsius == 3000);

assert(controller.current.celsius == 1000);
assert(controller.current.celsius == 2000);
assert(controller.current.celsius == 3000);

// etcetera . . .