Arduino project · Light sensing · Medium
SD Card Light Logger
The brightness of a room is saved to an SD card every 5 seconds.
What you will learn
- How to log slowly changing data
- How to read the file in Excel
- How to find the sunrise from data
How it works
A new line (time, brightness) is added to LOG.TXT every 5 seconds.
Try this next
- Log for a whole day and draw the graph.
- Compare two rooms with two loggers.
- Add a lamp that follows the light.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
Day and night at the window
Move the light slider. The sun rises and sets, and the room gets bright or dark.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- Light sensor = daylight