Passive Infrared (PIR) motion sensors are one of the simplest and most effective ways to detect motion in a room. Combined with an ESP32, they provide extremely fast, local, cloud-free motion detection that integrates perfectly with Home Assistant.

This guide covers two methods:

1. ESPHome – automatic discovery
2. MQTT – manual configuration for advanced setups

Both wiring and software options are included.

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1. Hardware Required

• ESP32 DevKit
• HC-SR501 or AM312 PIR motion sensor
• Jumper wires
• USB cable

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2. PIR Sensor Wiring

Most PIR sensors operate at 3.3V–5V and include three pins:

ESP32 → PIR
3.3V → VCC
GND  → GND
GPIO34 → OUT

GPIO34 is used because it is an input-only pin suitable for sensors.

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METHOD 1 — ESPHome Integration

ESPHome automatically detects PIR state changes and exposes a binary_sensor entity in Home Assistant.

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3. ESPHome PIR YAML

esphome:
  name: esp32-pir
  platform: ESP32
  board: esp32dev

wifi:
  ssid: "YOUR_WIFI"
  password: "YOUR_PASSWORD"

logger:
api:
ota:

binary_sensor:
  - platform: gpio
    pin:
      number: 34
      mode:
        input: true
    name: "Living Room Motion"
    device_class: motion
    filters:
      - delayed_off: 2s

Notes

• delayed_off prevents flickering when motion stops
• device_class: motion gives the correct icon in Home Assistant

After uploading, the sensor appears automatically under:

Settings → Devices & Services → ESPHome

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METHOD 2 — MQTT Integration (Manual YAML)

For setups using MQTT, the PIR sends a JSON message via ESP32 every time motion is detected.

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4. Home Assistant configuration.yaml — Correct MQTT Syntax

mqtt:
  binary_sensor:
    - name: "Living Room PIR Motion"
      state_topic: "home/livingroom/pir"
      payload_on: "1"
      payload_off: "0"
      device_class: motion

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5. ESP32 MQTT Code for PIR Sensor

Works with HC-SR501 and AM312 PIR modules.

#include <WiFi.h>
#include <PubSubClient.h>

#define PIR_PIN 34
#define WIFI_SSID "YOUR_WIFI"
#define WIFI_PASS "YOUR_PASSWORD"
#define MQTT_SERVER "192.168.0.10"

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);

  pinMode(PIR_PIN, INPUT);

  WiFi.begin(WIFI_SSID, WIFI_PASS);
  while (WiFi.status() != WL_CONNECTED) delay(500);

  client.setServer(MQTT_SERVER, 1883);
}

void loop() {
  if (!client.connected()) {
    while (!client.connected()) client.connect("ESP32_PIR");
  }

  int motion = digitalRead(PIR_PIN);

  if (motion == HIGH)
    client.publish("home/livingroom/pir", "1");
  else
    client.publish("home/livingroom/pir", "0");

  client.loop();
  delay(200);
}

The PIR value updates every 200 ms for fast responsiveness.

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6. Home Assistant Dashboard Example

type: entities
entities:
  - entity: binary_sensor.living_room_pir_motion

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7. Example Automations

Turn lights on when motion is detected

automation:
  - alias: "Lights On With Motion"
    trigger:
      - platform: state
        entity_id: binary_sensor.living_room_pir_motion
        to: "on"
    action:
      - service: light.turn_on
        target:
          entity_id: light.living_room

Turn lights off after 2 minutes of no motion

  - alias: "Lights Off After No Motion"
    trigger:
      - platform: state
        entity_id: binary_sensor.living_room_pir_motion
        to: "off"
        for: "00:02:00"
    action:
      - service: light.turn_off
        target:
          entity_id: light.living_room

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8. Troubleshooting

PIR always reads ON

• Reduce sensitivity using onboard potentiometer (HC-SR501 only)
• Check for heat sources (TVs, heaters)
• Avoid pointing at windows

PIR never reads ON

• Wrong pin (GPIO34 recommended)
• PIR requires ~30 seconds warm-up after power on

False triggers

• Electrical noise → add 0.1µF capacitor between VCC/GND
• Use AM312 miniature PIR for better stability

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9. PIR Sensor Comparison

Model	Voltage	Sensitivity	Notes
HC-SR501	5V	Adjustable	Most common, long range
AM312	3.3V	Fixed	Small, ideal for ESP32
SR602	3–5V	Medium	Ultra-compact

AM312 is the best match for ESP32 due to 3.3V operation and low noise.

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