Smart Grayscale Sensor

A grayscale sensor is an analog sensor that, when used with Arduino, can detect different colors on the ground or tabletop and generate corresponding signals. This allows for interactive projects related to color and can also serve as a line-following sensor for line-following robots or a grayscale detection sensor for football robots.

The grayscale sensor includes a high-brightness white LED (Light Emitting Diode) and a photoresistor. When the LED illuminates paper with different grayscale levels, the reflected light varies. The photoresistor receives this reflected light, and its resistance changes based on the light intensity, allowing the measurement of grayscale values.

Schematic Diagram

Working Principle

The main components of the grayscale sensor are:

1. LED: Usually a high-brightness white LED that illuminates the target surface.
2. Photoresistor (LDR): Receives the light reflected from the target surface.

When the LED illuminates surfaces of different grayscale levels (colors), different amounts of light are reflected:

• Lighter surfaces: Reflect more light, resulting in higher light intensity received by the photoresistor.
• Darker surfaces: Reflect less light, resulting in lower light intensity received by the photoresistor.

The photoresistor changes its resistance based on the received light intensity. Through a voltage divider circuit (typically formed by connecting the photoresistor in series with a fixed resistor), the changes in light intensity are converted to voltage changes. The analog input pin of the Arduino can read these voltage changes, thus determining the grayscale value.