PIR Sensors for Arduino Projects: Buyer's Guide

Introduction

With dozens of PIR modules available, choosing the right one for your Arduino project can be confusing. This guide covers the most popular options and when to use each.

Popular PIR Modules

HC-SR501 – The Classic

Price: $2-3
Voltage: 4.5-20V (5V recommended)
Output: 3.3V digital HIGH
Standby current: 50-65µA
Pros: Cheap, adjustable sensitivity and hold time, works with 5V Arduino
Cons: Higher power, not 3.3V compatible without level shifting
Best for: Beginners, USB-powered projects, 5V boards

AM312 – Mini Low-Power

Price: $2-3
Voltage: 2.7-12V (works at 3.3V)
Output: 3.0V digital HIGH
Standby current: 35µA
Pros: Small (10×8mm), low power, 3.3V compatible
Cons: Fixed 2-second hold time, shorter range (3-5m)
Best for: Battery projects, ESP32/Raspberry Pi, compact designs

Panasonic EKMB – Premium Low Power

Price: $8-12
Voltage: 2.3-4.0V
Output: Open-drain (requires pull-up)
Standby current: 1-6µA
Pros: Ultra-low power, high sensitivity, excellent temperature stability
Cons: More expensive, requires pull-up resistor
Best for: Battery projects, professional products

Comparison Table

4.5-20V

50-65µA

3-7m

32×24mm

2.7-12V

35µA

3-5m

10×8mm

2.3-4V

1-6µA

5-12m

Various

表

Power Considerations

Battery-Powered Projects

AM312: 35µA – good for 6-12 months on 2xAA
Panasonic EKMB: 1-6µA – excellent for 2-4 years
Avoid HC-SR501: 50-65µA reduces battery life significantly

3.3V Microcontrollers (ESP32, Raspberry Pi Pico)

AM312: Direct connection (2.7-12V input, 3.0V output)
Panasonic EKMB: Direct with pull-up to 3.3V
HC-SR501: Power at 5V, use voltage divider on output

Sample Code

HC-SR501 / AM312

const int pirPin = 2;
void setup() {
  pinMode(pirPin, INPUT);
  Serial.begin(9600);
}
void loop() {
  if (digitalRead(pirPin) == HIGH) {
    Serial.println("Motion detected!");
  }
  delay(100);
}

Panasonic EKMB (with pull-up)

const int pirPin = 2;
void setup() {
  pinMode(pirPin, INPUT_PULLUP);
  Serial.begin(9600);
}
void loop() {
  if (digitalRead(pirPin) == LOW) {  // Inverted logic
    Serial.println("Motion detected!");
  }
  delay(100);
}

Conclusion

For most beginners, the HC-SR501 is the best starting point due to its low cost and adjustable settings. For battery-powered projects, the AM312 offers a good balance of size and power consumption. For professional or long-term projects, the Panasonic EKMB series provides superior reliability and ultra-low power.

PIR Sensors for Arduino Projects: Buyer’s Guide