Overview

The VEML7700 is a 16-bit high-accuracy digital ambient light sensor (ALS) manufactured by Vishay Semiconductors. Designed for display brightness control, backlight dimming, and weather station monitoring, it features Vishay's proprietary Filtron technology, which matches the spectral response of the human eye (peak $550\text{ nm}$).

Offering an extreme dynamic range from 0.0036 Lux to 120,000 Lux (resolving sub-lux moonlight up to direct full sunlight), programmable gain settings ($\frac{1}{8}, \frac{1}{4}, 1, 2$), adjustable integration times ($25\text{ ms}$ to $800\text{ ms}$), and $I^2C$ communication, the VEML7700 is widely used on Adafruit and ESPHome sensor nodes.

Quick reference

Pinout

Standard 4-pin 0.1" (2.54 mm) header or Qwiic / STEMMA QT connector:

Specifications

$I^2C$ Register Map

The VEML7700 uses 16-bit register words (0x10 address):

Lux Calculation & Gain Multipliers

$\text{Lux} = \text{Raw ALS Code} \times \text{Resolution Scale Factor}$

For default settings ($\text{Gain} = 1$, $\text{Integration Time} = 100\text{ ms}$), the resolution multiplier is $0.0576\text{ Lux/digit}$.

High-lux nonlinear compensation formula (for raw Lux $> 1000$):

$\text{Lux}_{corrected} = 6.0135 \times 10^{-13} \times L^4 - 9.3924 \times 10^{-9} \times L^3 + 8.1488 \times 10^{-5} \times L^2 + 1.0023 \times L$

Wiring

Example

#include <Wire.h>
#include "Adafruit_VEML7700.h"

Adafruit_VEML7700 veml = Adafruit_VEML7700();

void setup() {
  Serial.begin(9600);
  while (!Serial) delay(10);

  Serial.println("Initializing VEML7700...");
  if (!veml.begin()) {
    Serial.println("VEML7700 not found! Check wiring.");
    while (1);
  }
  Serial.println("VEML7700 online.");

  veml.setGain(VEML7700_GAIN_1);
  veml.setIntegrationTime(VEML7700_IT_100MS);
}

void loop() {
  float lux = veml.readLux();
  Serial.print("Ambient Light: ");
  Serial.print(lux);
  Serial.println(" Lux");

  delay(1000);
}

Common mistakes

• I2C address collision: VEML7700 uses a fixed hardcoded address (0x10). Connecting multiple VEML7700 sensors to the same $I^2C$ bus requires an $I^2C$ multiplexer (such as TCA9548A).
• Clipping in bright outdoor sunlight: At default gain ($\times 1$), raw output clips at ~3,700 Lux. For outdoor solar measurements, set gain to $\frac{1}{8}$ (VEML7700_GAIN_1_8) and integration time to $25\text{ ms}$.

Notes

• VEML7700 vs BH1750: VEML7700 offers significantly higher sensitivity ($0.0036\text{ Lux}$ vs $1.0\text{ Lux}$) and wider dynamic range.