# async-i2c-bus
async-i2c-bus
Bus and Device classes for i2c-bus, with promised functions.
Bus and Device classes for i2c-bus, with promised functions.
You probably don't need this library anymore. The original purpose of the library was to have async
methods instead of callbacks. Currently i2c-bus
support promises.
Besides that it is still useful for me to have a class for Bus and Device, and an easy way to catch the errors produced in the bus, as well as typexcript typings. And it saves some time not having to write it for every library.
# Table of Contents
# Installation
yarn add async-i2c-bus
// or
npm i async-i2c-bus
# Usage
The package exports the Bus
, Device
and BusError
classes.
You can check the full documentation
# Bus
The Bus
wraps the original implementation with a typescript
class.
To create a Bus
use the static method create
or createAndOpen
(also opens the bus
) with the following signatures:
Bus.create({ busNumber }): Bus
Name | Type |
---|---|
busNumber | number |
Returns: Bus
Bus.createAndOpen({ busNumber }): Promise<Bus>
Name | Type |
---|---|
busNumber | number |
Returns: Promise‹Bus›
# Device
Device
inherits all the device-oriented methods from Bus
and calls them with the device's address.
Also you can extends / compose it to create your specific device class. Read further for an example of it.
To create a Device
use the static method create
with the following signature:
Device.create({ busNumber }): Device
Name | Type |
---|---|
bus | bus |
address | number |
Returns: Device
# BusError
All the errors thrown by the bus are wrapped into BusError
, which keeps the message and stack of the original error, but makes it easier to catch bus-specific errors.
# Example
import { Bus, Device } from 'async-i2c-bus';
const WEATHER_SENSOR_ADDRESS = 0x77;
const main = async () => {
const bus = Bus.create();
await bus.open();
const devices = await bus.scan();
console.log(`Connected devices ${devices}`);
const weatherSensor = Device.create({ address: WEATHER_SENSOR_ADDRESS, bus });
// Configure Weather Sensor (BMP280)
await weatherSensor.writeByte(0xf4, 0b00100101);
await weatherSensor.writeByte(0xf5, 0b00100100);
// Read temperature
const temperatureBuffer = Buffer.alloc(3);
await weatherSensor.readI2cBlock(0xfa, 3, temperatureBuffer);
const temperature = temperatureBuffer.readUIntBE(0, 3) >>> 4;
console.log(`Temperature: ${temperature}`);
};
# Example using custom device
import { Device } from 'async-i2c-bus';
const WEATHER_SENSOR_ADDRESS = 0x77;
class WeatherSensor {
constructor({ bus }) {
this.device = Device.create({ bus, address: WEATHER_SENSOR_ADDRESS });
}
async readTemperature() {
const buffer = Buffer.alloc(3);
await this.bus.readI2cBlock(0xfa, 3, buffer);
return buffer.readUIntBE(0, 3) >>> 4;
}
}
# License
Licensed under MIT.