What Is a Sensor?
A sensor is a component that converts a physical quantity — such as temperature, light, pressure or motion — into a measurable electrical signal. It's like the "sense organs" of electronic systems, bringing the real world into the circuit.
How Does a Sensor Work?
The material inside the sensor changes one of its electrical properties (resistance, voltage, capacitance) as the quantity it measures changes. This change is read and processed. This conversion is called transduction.
Analog and Digital Sensors
| Type | Output | Example |
|---|---|---|
| Analog | Continuous voltage/resistance | LM35, LDR |
| Digital | I2C/SPI data | DS18B20, BME280 |
Sensor Types
There are hundreds of sensor types — temperature, light, pressure, humidity, motion (acceleration/gyroscope), distance, magnetic field, gas, sound and image — each measuring a different physical quantity. Common ones: pressure, humidity, gas, light/color, proximity, capacitive touch and image sensors.
How Is a Sensor Output Read?
Analog sensors are read with an ADC (through a voltage divider if needed); digital sensors connect directly to the microcontroller over I2C/SPI.
What to Look At When Choosing a Sensor
The measurement range, sensitivity, accuracy, output type (analog/digital), supply voltage and operating temperature are the most important criteria; all are given in the datasheet.
Common Mistakes
- Skipping calibration: most sensors need calibration for accurate readings.
- Mixing up the output type: mistaking an analog sensor for I2C and connecting it wrong.
- Ignoring noise: a weak sensor signal needs a filter and good grounding.
Frequently Asked Questions
Analog or digital sensor?+
Why is a sensor output amplified?+
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