OPT3001 ambient light sensor

The TI OPT3001 measures light in lux the way the eye sees it, from 0.01 to 83865 lux, auto-ranging, over I2C at 0x44.

Aliases: OPT3001 module, CJMCU-3001, ClosedCube OPT3001, lux meter. Its filter blocks infrared, so it agrees with the eye where a plain photodiode reads high under incandescent light. A screen dims with it; a greenhouse logs with it.

Pins

Pin	What it does
VCC, GND	Supply, 3 to 5 V on the board.
SCL, SDA	I2C. The board carries the pull-ups.
INT	The limit or conversion-ready interrupt, active low.

Properties

address, 0x44 to 0x47. lux is the light; the slider changes it.

Reading it on an Arduino

With ClosedCube's library, which Mokxi ships as ClosedCube_OPT3001.h:

#include <ClosedCube_OPT3001.h>
ClosedCube_OPT3001 opt3001;

void setup() {
  Serial.begin(9600);
  opt3001.begin(0x44);
  OPT3001_Config config;
  config.rawData = 0;
  config.RangeNumber = 0b1100;
  config.ModeOfConversionOperation = 0b11;
  opt3001.writeConfig(config);
}

void loop() {
  Serial.println(opt3001.readResult().lux);
  delay(500);
}

How it talks

Sixteen-bit registers: 0x00 the result, an exponent and a twelve-bit mantissa, lux = 0.01 x 2^E x R; 0x01 the configuration (range, 100 or 800 ms, the mode and the flags); 0x02 and 0x03 the limits; 0x7E 0x5449 and 0x7F 0x3001. It powers up shut down; continuous mode converts every 100 or 800 ms and sets the conversion ready flag, which reading the configuration clears.

What it does not model

The fault count and the spectral response: the slider is the reading.

Common mistakes

Reading the result before a conversion has finished: it reads zero until the first one, 100 or 800 ms after the mode is set.