VEML6075 on OLED: UV Index
Overview & Wiring
What it is: The VEML6075 measures ultraviolet light and computes a UV Index (UVI) — the same 0–11+ scale weather apps use for sunburn risk. It reads separate UVA and UVB channels.
How it works: I2C device at address 0x10. The Adafruit library applies the manufacturer's coefficients to turn raw UVA/UVB into a UV Index. Shares SDA/SCL with the OLED.
Wiring (shared I2C bus with the OLED):
VEML6075 SDA -> GPIO4
VEML6075 SCL -> GPIO5
VEML6075 VCC -> 3V3
VEML6075 GND -> GND
OLED VCC=3V3, GND=GND, SDA=GPIO4, SCL=GPIO5
Libraries: "Adafruit VEML6075" (installs "Adafruit BusIO"), plus "Adafruit SSD1306" and "Adafruit GFX Library".
On screen / Serial: the UV Index (one decimal). Take it outside on a sunny day vs indoors to see the difference.
Gotchas: Address 0x10 is fixed. Indoors the UVI is near 0 because glass blocks most UV — test it in real sunlight. If you can't find a VEML6075, the newer LTR390 is a common drop-in alternative (different library).
Circuit Diagram
Parts You Need
Source Code (Arduino / ESP32)
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_VEML6075.h>
Adafruit_SSD1306 display(128, 64, &Wire, -1);
Adafruit_VEML6075 uv = Adafruit_VEML6075();
void setup() {
Serial.begin(115200);
Wire.begin(4, 5);
display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
if (!uv.begin()) {
Serial.println("VEML6075 not found");
display.setTextColor(SSD1306_WHITE);
display.setCursor(0, 28); display.println("VEML6075 not found");
display.display();
while (1) delay(10);
}
}
void loop() {
float uvi = uv.readUVI();
display.clearDisplay();
display.setTextColor(SSD1306_WHITE);
display.setTextSize(1);
display.setCursor(0, 0);
display.println("VEML6075 UV");
display.setTextSize(3);
display.setCursor(0, 22);
display.printf("%.1f", uvi);
display.setTextSize(1);
display.setCursor(0, 54); display.print("UV index");
display.display();
Serial.printf("UV index: %.2f\n", uvi);
delay(1000);
}