BH1750

Introducción

The BH1750 provides 16-bit light measurements in lux, the SI unit for measuring light making it easy to compare against other values like references and measurements from other sensors. Able to measure from 0 to 65K+ lux, the BH1750.

📖 from adafruit

Specifications

• I2C bus Interface
• Spectral responsibility is approximately human eye response
• Illuminance to digital converter
• Range: 1 – 65535 lux
• Low current by power down function
• 50Hz / 60Hz Light noise reject-function
• It is possible to select 2 different I2 C slave-addresses
• Small measurement variation (+/- 20%)
• The influence of infrared is very small
• Supports continuous measurement mode
• Supports one-time measurement mode

Measurement Modes

The sensor supports two different measurement modes: continuous measurement mode, and one-time measurement mode. Each mode supports three different resolution modes.

Mode	Precision	Time
Low Resolution Mode	4 lux precision	16 ms measurement time
High Resolution Mode	1 lux precision	120 ms measurement time
High Resolution Mode 2	0.5 lux precision	120 ms measurement time

In continuous measurement mode, the sensor continuously measures ambient light values. In one-time measurement mode, the sensor measures the ambient light value once, and then it goes to power down mode.

datasheet

🧾 Hay mucha más información en el datasheet
y algunos recursos extras en la sección de digital light sensors

Luminous flux

In photometry, luminous flux or luminous power is the measure of the perceived power of light. It differs from radiant flux, the measure of the total power of electromagnetic radiation (including infrared, ultraviolet, and visible light), in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light.

The SI unit of luminous flux is the lumen (lm). One lumen is defined as the luminous flux of light produced by a light source that emits one candela of luminous intensity over a solid angle of one steradian.

📖 wikipedia

Obteniendo datos

Pin	Description
VCC	Powers the sensor (3.3V or 5V)
GND	Common GND
SCL	SCL pin for I2C communication
SDA	(Data) SDA pin for I2C communication
ADDR	Selects address

i2c

Este sensor utiliza el protocolo I2C

The Inter-Integrated Circuit (I2C) Protocol is a protocol intended to allow multiple "peripheral" digital integrated circuits ("chips") to communicate with one or more "controller" chips. Like the Serial Peripheral Interface (SPI), it is only intended for short distance communications within a single device. Like Asynchronous Serial Interfaces (such as RS-232 or UARTs), it only requires two signal wires to exchange information.

📖 sparkfun

Circuito

El cirucito es muy sencillo solo necesitas conectar el pin VCC a 3.3v, GND y los pines del bus I2C: SCL→D1 y SDA→D2.

Librería

Para leer este sensor, podemos utilizar la librería Light-Sensor BH1750. Puedes encontrar muucha más información sobre sus capacidades y como utilizarla en su wiki

Para probar si nuestro sensor está bien conectado y todo funciona, podemos usar un simple código como este:

#include <Arduino.h>
#include <hp_BH1750.h>

hp_BH1750 BH1750;       //  create the sensor

void setup()
{
  Serial.begin(115200);

  bool avail = BH1750.begin(BH1750_TO_GROUND);// init the sensor with address pin connetcted to ground
                                              // result (bool) wil be be "false" if no sensor found
  if (!avail) {
    Serial.println("No BH1750 sensor found!");
    while (true) {};                                        
  }
}

void loop()
{
  BH1750.start();   //starts a measurement
  float lux=BH1750.getLux();  //  waits until a conversion finished
  Serial.println(lux);        
}

si todo está bien conectado, abriendo el Serial plotter deberías ver una gráfica que varía según el nivel de luminosidad que llega al sensor. Prueba a hacerle sombra y a iluminarlo con una lámpara!