Arduino UNO Q - Automated Light Control with Motion Sensor and LED Strip
In this guide, you will learn how to build an automated light control system using an HC-SR501 motion sensor and a 12V LED strip with Arduino UNO Q. The LED strip turns on when motion is detected and off when motion stops. Ideal for:
- Staircase lighting
- Under-bed lighting
- Hallway night lights
- Christmas tree lights
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .
Additionally, some of these links are for products from our own brand, DIYables .
Overview of LED Strip and Motion Sensor
Learn about the LED strip and motion sensor in the tutorials below:
Initial Sensor Setting
| Time Delay Adjuster | Screw fully anti-clockwise (minimum delay). |
| Detection Range Adjuster | Screw fully clockwise (maximum range). |
| Repeat Trigger Selector | Place jumper in repeatable trigger mode. |
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
The relay acts as a switch between the 12V power supply and the LED strip. The Arduino UNO Q MCU controls the relay's IN pin.
MCU Code
The Arduino UNO Q has two processors: the STM32 MCU (handles real-time hardware control) and the Qualcomm MPU (runs Debian Linux). In this section, only the STM32 MCU is programmed — the Linux side stays idle. A later section will show how both processors work together.
/*
* This Arduino UNO Q code was developed by newbiely.com
*
* This Arduino UNO Q code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-q/arduino-uno-q-automated-light-control-with-motion-sensor-and-led-strip
*/
#define MOTION_SENSOR_PIN 7 // The Arduino UNO Q pin connected to the OUTPUT pin of the motion sensor
#define RELAY_PIN 9 // The Arduino UNO Q pin connected to the IN pin of the relay (controls LED strip)
int motion_state = LOW;
int prev_motion_state = LOW;
void setup() {
pinMode(MOTION_SENSOR_PIN, INPUT);
pinMode(RELAY_PIN, OUTPUT);
digitalWrite(RELAY_PIN, LOW); // LED strip off initially
}
void loop() {
prev_motion_state = motion_state;
motion_state = digitalRead(MOTION_SENSOR_PIN);
if (prev_motion_state == LOW && motion_state == HIGH) {
// Motion detected — turn LED strip on
digitalWrite(RELAY_PIN, HIGH);
} else if (prev_motion_state == HIGH && motion_state == LOW) {
// Motion stopped — turn LED strip off
digitalWrite(RELAY_PIN, LOW);
}
}
Detailed Instructions
- First time with Arduino UNO Q? Follow the Getting Started with Arduino UNO Q tutorial to get your development environment ready before proceeding.
- Wire the components: Connect sensor OUTPUT → pin 7, relay IN → pin 9. Connect the LED strip through the relay to the 12V power supply.
- Connect: Plug the Arduino UNO Q into your computer with a USB-C cable.
- Open Arduino App Lab: Launch Arduino App Lab and wait until it detects your Arduino UNO Q.
- Create a new App: Click the Create New App button.
- Give the App a name, for example: DIYables_AutoLight
- Click Create to confirm.
- You will see a set of folders and files generated inside your new App.
- Find the sketch/sketch.ino file — this is where you will paste the MCU sketch.
Paste the sketch: Copy the MCU code above and paste it into the sketch file. Keep other files as default.
- Install the library: Click the Add sketch library button (the open book icon with a + sign) in the left sidebar.
- Search for Arduino_RouterBridge created by Arduino and click the Install button.
Bricks
No bricks added...
Sketch Libraries
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Files
python
sketch
.gitignore
README.md
app.yaml
sketch.ino
- Upload: Click the Run button in Arduino App Lab to compile and upload to the STM32.
- Test: Walk in front of the sensor — the LED strip should turn on when motion is detected and off when motion stops.
Linux + MCU Bridge Programming
The Arduino UNO Q has two processors that work together: the MPU (Qualcomm, runs Debian Linux) and the MCU (STM32, runs Zephyr OS with your Arduino sketch). They communicate using RPC via the Arduino_RouterBridge library — never via raw serial ports.
- The motion sensor and relay are both connected to the MCU (STM32) — sensor on pin 7, relay on pin 9.
- The MPU cannot control them directly — it calls Bridge.call("check_motion") on the MCU, which reads the sensor and switches the relay (and LED strip) accordingly.
- The MPU has Wi-Fi — because the MPU runs full Debian Linux with Wi-Fi, it can report light status to Telegram.
- Communication: Bridge.call() on the Linux side invokes Bridge.provide_safe() on the MCU side (since digitalWrite() is used to control the relay)
- ⚠️ Reserved: /dev/ttyHS1 (Linux) and Serial1 (MCU) are used by the Arduino Router — never open them directly
In short: MPU polls sensor → MCU reads pin, switches relay (LED strip), and reports to Monitor.
MCU sketch — automated lighting with Bridge:
/*
* This Arduino UNO Q code was developed by newbiely.com
*
* This Arduino UNO Q code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-q/arduino-uno-q-automated-light-control-with-motion-sensor-and-led-strip
*/
#include "Arduino_RouterBridge.h"
#define MOTION_SENSOR_PIN 7
#define RELAY_PIN 9
int motion_state = LOW;
int prev_motion_state = LOW;
void check_motion() {
prev_motion_state = motion_state;
motion_state = digitalRead(MOTION_SENSOR_PIN);
if (prev_motion_state == LOW && motion_state == HIGH) {
digitalWrite(RELAY_PIN, HIGH);
Monitor.println("Motion detected! LED strip ON");
} else if (prev_motion_state == HIGH && motion_state == LOW) {
digitalWrite(RELAY_PIN, LOW);
Monitor.println("Motion stopped! LED strip OFF");
} else {
Monitor.println(motion_state == HIGH ? "Motion: ACTIVE | LED strip: ON" : "Motion: none | LED strip: OFF");
}
}
void setup() {
Bridge.begin();
Monitor.begin();
pinMode(MOTION_SENSOR_PIN, INPUT);
pinMode(RELAY_PIN, OUTPUT);
digitalWrite(RELAY_PIN, LOW);
Bridge.provide_safe("check_motion", check_motion);
Monitor.println("Automated Lighting Bridge ready");
}
void loop() {}
Python script (Arduino App Lab) — poll motion state every 0.5 seconds:
/*
* This Arduino UNO Q code was developed by newbiely.com
*
* This Arduino UNO Q code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-q/arduino-uno-q-automated-light-control-with-motion-sensor-and-led-strip
*/
from arduino.app_utils import *
import time
def loop():
Bridge.call("check_motion")
time.sleep(0.5)
App.run(user_loop=loop)
- Note: Make sure Bridge.begin() is called in the MCU sketch and the sketch is uploaded before running the Python script on the Linux side.
- ⚠️ Warning: Never directly open /dev/ttyHS1 (on Linux) or use Serial1 (on MCU) in your code — these are reserved by the Arduino Router and accessing them will break the Bridge.
Detailed Instructions
- Upload the MCU sketch: Open Arduino App Lab, create a new App, paste the Bridge MCU sketch into sketch/sketch.ino, install the Arduino_RouterBridge library, and click Run.
- Add the Python script: Paste the Python code above into the Python tab of the same App.
- Run the App: Click Run — Python polls motion every 0.5 seconds; MCU switches the LED strip.
- Check the console: Open the Console tab → MCU Monitor subtab and walk in front of the sensor.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
Automated Lighting Bridge ready
Motion detected! LED strip ON
Motion stopped! LED strip OFF
Motion detected! LED strip ON
Motion stopped! LED strip OFF
Telegram Integration
Monitor automated lighting status remotely via Telegram.
If you do not have a Telegram bot yet, see How to Create a Telegram Bot to get your bot token before continuing.
MCU sketch: Keep the same MCU sketch from the previous Bridge section — no changes needed. Make sure it is already uploaded and running on the STM32 before proceeding.
Python script (Arduino App Lab) — Telegram bot for automated lighting:
/*
* This Arduino UNO Q code was developed by newbiely.com
*
* This Arduino UNO Q code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-q/arduino-uno-q-automated-light-control-with-motion-sensor-and-led-strip
*/
from arduino.app_utils import *
import requests
import time
BOT_TOKEN = "YOUR_BOT_TOKEN"
API_URL = f"https://api.telegram.org/bot{BOT_TOKEN}"
last_update_id = 0
def send_message(chat_id, text):
requests.post(f"{API_URL}/sendMessage", json={"chat_id": chat_id, "text": text})
def get_updates():
global last_update_id
resp = requests.get(f"{API_URL}/getUpdates", params={"offset": last_update_id + 1, "timeout": 5})
return resp.json().get("result", [])
def loop():
global last_update_id
updates = get_updates()
for update in updates:
last_update_id = update["update_id"]
msg = update.get("message", {})
chat_id = msg.get("chat", {}).get("id")
text = msg.get("text", "").strip()
if text == "/status":
status = Bridge.call("check_motion")
send_message(chat_id, status if status else "No motion state change since last check.")
else:
send_message(chat_id, "Commands:\n/status — check motion state and update LED strip")
time.sleep(0.5)
App.run(user_loop=loop)
- Note: Replace YOUR_BOT_TOKEN with the token obtained from @BotFather on Telegram.
- Send /status to manually check the motion sensor and update the LED strip.
Detailed Instructions
- Upload the MCU sketch: Use the Bridge MCU sketch from the previous section (upload it first if not already done).
- Paste the Telegram script: Copy the Python code above into the Python tab of your App in Arduino App Lab.
- Set your token: Replace YOUR_BOT_TOKEN in the script with your actual bot token.
- Run the App: Click Run — the bot starts listening for Telegram messages.
- Test it: Send /status — the bot replies with the motion state and LED strip state.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
[2026-04-29 12:00:01] Telegram: /status
[2026-04-29 12:00:01] Motion: none | LED strip: OFF
[2026-04-29 12:01:30] Telegram: /status
[2026-04-29 12:01:30] Motion detected! LED strip ON
Telegram
12:45
Welcome to Telegram!
ArduinoBot
10:19
Chatting with Arduino...
BotFather
Yesterday
Your bot has been created.
ArduinoBot
bot
OpenClaw Integration
OpenClaw integration for Arduino UNO Q automated lighting is coming soon.
- Coming Soon: OpenClaw support for this project on Arduino UNO Q will be covered in a future update.
Application/Project Ideas
- Hallway night light: Automatically light the hallway when someone walks through at night
- Staircase lighting: Illuminate stairs when someone approaches for safety
- Under-bed light: Create a dramatic effect that lights up when you get out of bed
- Cabinet lighting: Turn on LED strip inside a cabinet when you open it and someone is nearby
- Garden path lighting: Light up garden paths when motion is detected at night
Challenge Yourself
- Easy: Adjust the relay's time delay potentiometer to keep the light on longer after motion stops
- Medium: Combine with an LDR — only activate the LED strip when it's dark AND motion is detected
- Advanced: Send an automatic Telegram notification when the LED strip turns on