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.
yarn add async-i2c-bus
// or
npm i async-i2c-bus
The package exports the Bus, Device and BusError classes.
You can check the full documentation
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 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
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.
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}`);
};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;
}
}
Licensed under MIT.
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