Barometer

I2C

input

Medium RAM

0.4.1

#Description

This sensor is able to read the pressure in the air. You could use this, for example, to get the altitude in which your project is running.

#Links

Open Wiki for Grove Component Get the Grove Component

#Units

Celsius°C
Fahrenheit°F
KelvinK
KilopascalkPa
HectopascalhPa
Metersm
Feetft

#Aliases

Air Pressure Sensor

#Functions

#JavaScript / Node.js

@blokdots/components on npm ↗

ClassBarometerextends I2cComponentBase

Barometer component for reading pressure and temperature from BMP280 sensor. This is an I2C component that emits change events when values change.

#Value type

TypeScript

interface BarometerValue {
  pressure: number;  // in hPa
  temperature: number;  // in °C
  altitude: number;  // in m
}

#Constructor options

Option	Type	Required	Description	Inherited from
`frequency`	`number`	optional	—
`pin`	`I2CPinID`	required	—	I2cComponentBase

#Events

Event	Parameters	Description
`change`	`value: BarometerValue`	—

#Methods

get pressure→ number

Get current pressure in hPa.

get temperature→ number

Get current temperature in °C.

get altitude→ number

Get current altitude in meters.

get i2cId→ I2CPinIDfrom I2cComponentBase

The resolved I2C pin ID (e.g. "i2c-0"). Useful for logging or passing back to the Arduino sketch.

#Example

JavaScript

import { Board, Barometer } from "@blokdots/components";

const board = new Board("/dev/ttyACM0");
await board.open();

const barometer = new Barometer({ board, pin: "example", frequency: 1000 });

barometer.on("change", (value) => {
  console.log("Barometer changed:", value);
});

#C++ (Arduino)

ClassBarometerextends ComponentBase

Barometric pressure + temperature sensor using Adafruit_BMP280 Emits ONE event when temp/pressure/altitude change significantly (atomic snapshot)

#Required libraries

#include <Adafruit_BMP280.h> — Adafruit BMP280 Library v2.6.8
#include "SPL07-003.h" — Seeed Arduino SPA06
#include <Wire.h> — Wire
#include <SPI.h> — SPI

#Setup

C++

#include "blokdots.h"

Barometer myComponent(eventBus, MY_EVENT);

#Constructor

Barometer(bus, evtChange, i2cAddress, seaLevelhPa, tempThresholdC, pressureThresholdPa, altitudeThresholdM, sampleIntervalMs, minEmitIntervalMs)

Parameter	Type	Default
`bus`	`EventBus`	required
`evtChange`	`uint8_t`	required
`i2cAddress`	`uint8_t`	`0x77`
`seaLevelhPa`	`float`	`1013.25f`
`tempThresholdC`	`float`	`0.2f`
`pressureThresholdPa`	`float`	`50.0f`
`altitudeThresholdM`	`float`	`0.5f`
`sampleIntervalMs`	`uint16_t`	`50`
`minEmitIntervalMs`	`uint16_t`	`200`

#Methods

temperatureC()→ float

pressurePa()→ float

pressurehPa()→ float

altitudeM()→ float

rawTemperatureC()→ float

Optional: most recent sample (may be newer than last event)

rawPressurePa()→ float

rawPressurehPa()→ float

rawAltitudeM()→ float

address()→ uint8_t

Optional debug helper (non-breaking addition)

setSeaLevelhPa(v)

Optional: update sea level reference at runtime (no event emitted automatically)

Parameter	Type	Default
`v`	`float`	required

emittedValue()→ const char*

NOTE: Uses dtostrf — AVR snprintf does not support %f