Si1145 UV detector ESP8266 project

In this ESP8266 project we will create a UV detector using a Wemos Mini connected to a triple base shield and with a TFT 1.44 shield fitted as well. We then connect an Si1145 sensor to this

This is a picture of my setup

The Si1145/46/47 is a low-power, reflectance-based, infrared proximity, ultraviolet (UV) index, and ambient light sensor with I2C digital interface and programmable event interrupt output. This touchless sensor IC includes an analog-to-digital converter, integrated high-sensitivity visible and infrared photodiodes, digital signal processor, and one, two, or three integrated infrared LED drivers with fifteen selectable drive levels.

The Si1145/46/47 offers excellent performance under a wide dynamic range and a variety of light sources including direct sunlight. The Si1145/46/47 can also work under dark glass covers.

The photodiode response and associated digital conversion circuitry provide excellent immunity to artificial light flicker noise and natural light flutter noise. With two or more LEDs, the Si1146/47 is capable of supporting multiple-axis proximity motion detection. The Si1145/46/47 devices are provided in a 10-lead 2×2 mm QFN package and are capable of operation from 1.71 to 3.6 V over the –40 to +85 °C temperature range.

TFT Connection

The shield uses the following pins

Parts List

You need the following parts

Layout/Schematic

This shows the Si1145 connection to a Wemos only – in my example I connect the sensor to the triple base shield

Code

This example requires the Adafruit Si1145 library, you can add this via the library manager or download from https://github.com/adafruit/Adafruit_SI1145_Library

You need to install the Adafruit_GFX and Adafruit_ST7735 libraries for the TFT. You can do this in the Arduino libraries

[codesyntax lang=”cpp”]

#include <Adafruit_GFX.h> // Core graphics library
#include <Adafruit_ST7735.h> // Hardware-specific library
#include <SPI.h>
#include <Wire.h>
#include "Adafruit_SI1145.h"

#define TFT_RST -1
#define TFT_CS D4
#define TFT_DC D3

Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS, TFT_DC, TFT_RST);
Adafruit_SI1145 uv = Adafruit_SI1145();

void setup(void)
{
  Serial.begin(9600);
  
  Serial.println("Adafruit SI1145 test");
  
  if (! uv.begin()) {
    Serial.println("Didn't find Si1145");
    while (1);
  }

  Serial.println("OK!");
  tft.initR(INITR_144GREENTAB);
  tft.setTextWrap(false); // Allow text to run off right edge
  tft.fillScreen(ST7735_BLACK);
}

void loop(void)
{
  tft.fillScreen(ST7735_BLACK);
  tft.setTextColor(ST7735_WHITE);
  tft.setTextSize(1);
  //title
  tft.setCursor(3, 3);
  tft.print("Si1145 example");
  //visible
  tft.setCursor(3, 13);
  tft.print("Vis: ");
  tft.println(uv.readVisible());
  //uv
  tft.setCursor(3, 23);
  float UVindex = uv.readUV();
  UVindex /= 100.0; 
  tft.print("UV: ");
  tft.println(UVindex);
  delay(1000);
}

[/codesyntax]

Link

https://www.silabs.com/documents/public/data-sheets/Si1145-46-47.pdf