Portable Luxmeter Using Arduino

This project is about making portable luxmeter. It can be used in schools, where children can measure different kinds of light sources.
Functions:

1. measure intensity of light in lux.

2. calculate solar irradiation from lux to watts/m2 (factor 112)

3. charging battery using USB port

Total cost is around 13 $ without case. Luxmeter take 15 mA, so it will works long time on one Li-Ion battery.

Step 1: BOM

• For project you need this components(affiliate links, if you want to support me):

Arduino Pro Mini 5V

• Link

MAX44009

• Wide 0.045 Lux to 188,000 Lux Range
  VCC = 1.7V to 3.6V ()
• ICC = 0.65µA Operating Current
• -40°C to +85°C Temperature Range
• Link

OLED display

• Diagonal Screen Size：0.96″
• Number of Pixels：128 x 64
• Color Depth：Monochrome (Yellow&Blue)
• Dimension：27.8 x27.3x 4.3 mm
• Working Voltage: 3.3~ 5V DC
• Power: 0.06W
• MaxViewing Angle: >160 Degree
• Duty：1/32Brightness ( cd/m2)：150 (Typ) @ 5V
• Interface： I2C
• Link

TP4056

• need USB to micro USB cable for charging
• input 5V
• Link

Li-Ion battery

• 3 – 4.2 Volts
• Link

18650 holder

• Link

Switch jumper

• Link

Cables and header

• female to female
• female and male header
• Link to cables
• Link to pin headers

Step 2: Circuit

You need of course 5V Arduino to power it with Li-Ion battery (4,2 V!)
Connections:

Arduino – MAX44009 (same for OLED display)

A4 – SDA

A5 – SCL

VCC – VIN

GND – GND

TP4056 – Arduino Pro Mini
OUT+ – VCC

Arduino – battery

VCC – plus terminal (max 5 V for Arduino 5V)

Arduino – switch jumper

GND – first switcher

TP4056 – switch jumper

OUT – – second switcher

Battery – switch jumper

minus terminal – first and second switcher

Step 3: Code

#include <Wire.h>

#include <Adafrfuit_SSD1306.h>
#include <Adafruit_GFX.h>

float lux;
float watts;

// OLED display TWI address
#define OLED_ADDR   0x3C
Adafruit_SSD1306 display(-1); // restart display with reset button on arduino

void setup() 

{

 Lux.Begin(0, 188000);
 display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);
 display.clearDisplay();
 display.display();

 // display a line of text
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setFont(&FreeSerif9pt7b);
  display.setCursor(1,15);
  display.print("MAX44009");
  display.display();
}

void loop()

{
lux=Lux.GetLux();  // get luxs
watts =Lux.GetWpm();  // get watts/m2, only for SUN source

display.fillRect(1, 20, 100, 100, BLACK); // create black rectangle on values position
display.setCursor(1,40);
display.print(lux);
display.setCursor(80,40);
display.print("lux");
display.setCursor(1,60);
display.print(watts);
display.setCursor(80,60); 
display.print("W/m");
display.setCursor(115,55);
display.print("2");
display.display();
delay(1000);
}

Read more: Portable Luxmeter