The **HC-SR501** motion sensor has several nice features such as sensitivity adjustment and trigger delay.
It is very simple to connect the HC-SR501 to your Arduino however this sensor requires 5 VDC so you will need to use a step-up regulator if you are running the 3.3V version of the Arduino Pro Mini.
Demonstration
A small video showing how to build a motion sensor:
Wiring Things Up
Start by connecting the radio module.
| Sensor | Arduino | Comment |
|---|---|---|
| GND | GND | Black |
| VCC | VCC (5-20V) | Red |
| OUT | Digital pin 3 (D3) | Green |
Trimpot Sx - Set sensitivity
Trimpot Tx - Trigger length (5sec - 200sec)
Example
/*
* The MySensors Arduino library handles the wireless radio link and protocol
* between your home built sensors/actuators and HA controller of choice.
* The sensors forms a self healing radio network with optional repeaters. Each
* repeater and gateway builds a routing tables in EEPROM which keeps track of the
* network topology allowing messages to be routed to nodes.
*
* Created by Henrik Ekblad <[email protected]>
* Copyright (C) 2013-2019 Sensnology AB
* Full contributor list: https://github.com/mysensors/MySensors/graphs/contributors
*
* Documentation: http://www.mysensors.org
* Support Forum: http://forum.mysensors.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
*******************************
*
* REVISION HISTORY
* Version 1.0 - Henrik Ekblad
*
* DESCRIPTION
* Motion Sensor example using HC-SR501
* http://www.mysensors.org/build/motion
*
*/
// Enable debug prints
// #define MY_DEBUG
// Enable and select radio type attached
#define MY_RADIO_RF24
//#define MY_RADIO_NRF5_ESB
//#define MY_RADIO_RFM69
//#define MY_RADIO_RFM95
#include <MySensors.h>
uint32_t SLEEP_TIME = 120000; // Sleep time between reports (in milliseconds)
#define DIGITAL_INPUT_SENSOR 3 // The digital input you attached your motion sensor. (Only 2 and 3 generates interrupt!)
#define CHILD_ID 1 // Id of the sensor child
// Initialize motion message
MyMessage msg(CHILD_ID, V_TRIPPED);
void setup()
{
pinMode(DIGITAL_INPUT_SENSOR, INPUT); // sets the motion sensor digital pin as input
}
void presentation()
{
// Send the sketch version information to the gateway and Controller
sendSketchInfo("Motion Sensor", "1.0");
// Register all sensors to gw (they will be created as child devices)
present(CHILD_ID, S_MOTION);
}
void loop()
{
// Read digital motion value
bool tripped = digitalRead(DIGITAL_INPUT_SENSOR) == HIGH;
Serial.println(tripped);
send(msg.set(tripped?"1":"0")); // Send tripped value to gw
// Sleep until interrupt comes in on motion sensor. Send update every two minute.
sleep(digitalPinToInterrupt(DIGITAL_INPUT_SENSOR), CHANGE, SLEEP_TIME);
}
