Arduino UNO Q - SW520D Tilt Sensor
A SW520D tilt sensor detects orientation changes and outputs a digital signal. It uses a simple ball switch mechanism — no potentiometer or analog output. Use it to trigger actions when an object is tilted, tipped, or moved. With Bridge and Telegram, your Arduino UNO Q can send you instant alerts when tilt is detected.
In this tutorial, you will learn:
- What a SW520D tilt sensor is and how it works
- How to wire the SW520D tilt sensor to the Arduino UNO Q MCU
- How to read the digital output to detect tilt
- How to use Bridge to expose tilt state and events to the Linux side (Python)
- How to receive Telegram alerts when tilt is detected on Arduino UNO Q
- How to use OpenClaw on Arduino UNO Q with the SW520D tilt sensor
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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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 the SW520D Tilt Sensor
A SW520D tilt sensor module detects orientation changes using a small metal ball inside a cylindrical housing. When the sensor is upright, the ball closes the electrical contact. When the sensor is tilted, the ball rolls away and opens the contact. The module outputs a simple digital signal:
- HIGH: Sensor is upright — no tilt detected
- LOW: Sensor is tilted — tilt detected
The module includes:
- VCC pin: 3.3V to 5V power supply
- GND pin: Ground
- DO pin: Digital output — HIGH = upright, LOW = tilt detected
- PWR LED: Power indicator
- Status LED: Reflects the tilt state — on when upright, off when tilted
image source: diyables.io
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
| SW520D Tilt Sensor Pin | Arduino UNO Q MCU |
|---|---|
| GND | GND |
| VCC | 5V |
| DO | D8 |
How To Program For SW520D Tilt Sensor
- Configure the sensor pin as a digital input:
pinMode(SENSOR_PIN, INPUT);
- Read the digital output:
int tilt_state = digitalRead(SENSOR_PIN);
- Detect tilt events by comparing to the previous state:
if (prev_state == HIGH && tilt_state == LOW)
Serial.println("Tilt DETECTED");
else if (prev_state == LOW && tilt_state == HIGH)
Serial.println("Tilt gone — upright again");
prev_state = tilt_state;
Arduino UNO Q Code
The Arduino UNO Q has two processors working together:
- The STM32 MCU reads the SW520D tilt sensor's digital output and detects tilt events
- The Qualcomm MPU runs Debian Linux with Wi-Fi — in this section, only the MCU is programmed. A later section shows how both processors work together via 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-sw520d-tilt-sensor
*/
// SW520D tilt sensor DO pin: HIGH = upright, LOW = tilt detected
#define SENSOR_PIN 8 // The Arduino UNO Q MCU pin connected to DO of the SW520D tilt sensor
int prev_tilt_state = HIGH;
int tilt_state;
void setup() {
Serial.begin(9600);
pinMode(SENSOR_PIN, INPUT);
Serial.println("Arduino UNO Q SW520D Tilt Sensor ready");
}
void loop() {
tilt_state = digitalRead(SENSOR_PIN);
if (prev_tilt_state == HIGH && tilt_state == LOW)
Serial.println("Tilt DETECTED");
else if (prev_tilt_state == LOW && tilt_state == HIGH)
Serial.println("Tilt gone — upright again");
prev_tilt_state = tilt_state;
}
Detailed Instructions
First time with Arduino UNO Q? Follow the Getting Started with Arduino UNO Q tutorial before proceeding.
- Connect: Wire the SW520D tilt sensor to the Arduino UNO Q MCU as shown in the wiring diagram.
- 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: SW520DTiltSensor
- Click Create to confirm.
- Paste the sketch: Copy the MCU code above and paste it into sketch/sketch.ino.
- Upload: Click the Run button in Arduino App Lab.
- Tilt the sensor back and forth — observe the Serial Monitor output.
- Make sure the sensor is mounted in the correct upright position for reliable detection.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
[2026-04-29 09:00:01] Arduino UNO Q SW520D Tilt Sensor ready
[2026-04-29 09:00:05] Tilt DETECTED
[2026-04-29 09:00:05] Tilt gone — upright again
[2026-04-29 09:00:08] Tilt DETECTED
[2026-04-29 09:00:08] Tilt gone — upright again
Bridge: Linux + MCU
This section shows how to program both processors of the Arduino UNO Q so the Linux side can read tilt state and receive tilt events via Bridge:
- The SW520D tilt sensor is connected to the MCU — the MCU monitors the digital output continuously and caches the current state
- The MPU cannot read the sensor pin directly — it calls Bridge functions to get the current state or check for new tilt events
- The MPU has Wi-Fi — running full Debian Linux, it can send Telegram alerts the moment tilt is detected
- Arduino_RouterBridge enables RPC communication between the two processors
- ⚠️ /dev/ttyHS1 (Linux) and Serial1 (MCU) are RESERVED by the router — never open them in user code
In short: MCU detects tilt via DO pin → sets event flag → MPU polls Bridge → MPU sends Telegram alert.
MCU Code (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-sw520d-tilt-sensor
*/
#include "Arduino_RouterBridge.h"
#define SENSOR_PIN 8 // The Arduino UNO Q MCU pin connected to DO of the SW520D tilt sensor
bool cached_tilt = false; // true = tilt present
bool tilt_event = false; // true = new tilt detected (falling edge)
int prev_state = HIGH;
String get_state(String arg) {
return cached_tilt ? "tilt" : "upright";
}
String get_event(String arg) {
if (tilt_event) {
tilt_event = false;
return "tilt_detected";
}
return "none";
}
void setup() {
Bridge.begin();
Monitor.begin();
pinMode(SENSOR_PIN, INPUT);
Bridge.provide("get_state", get_state);
Bridge.provide("get_event", get_event);
Monitor.println("Arduino UNO Q SW520D Tilt Sensor Bridge ready");
}
void loop() {
int current = digitalRead(SENSOR_PIN);
if (prev_state == HIGH && current == LOW) {
// Upright → Tilt
cached_tilt = true;
tilt_event = true;
Monitor.println("Tilt detected!");
} else if (prev_state == LOW && current == HIGH) {
// Tilt → Upright
cached_tilt = false;
Monitor.println("Upright again.");
}
prev_state = current;
}
Python Code (Bridge)
"""
This Arduino UNO Q script was developed by newbiely.com
This Arduino UNO Q script 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-sw520d-tilt-sensor
"""
from arduino.app_utils import *
import time
def loop():
state = Bridge.call("get_state")
print(f"Tilt state: {state}")
time.sleep(0.5)
App.run(user_loop=loop)
Detailed Instructions
- Connect: Wire the SW520D tilt sensor to the Arduino UNO Q as shown in the wiring diagram.
- Open Arduino App Lab and create a new App named TiltSensorBridge.
- Paste the MCU sketch into sketch/sketch.ino.
- Paste the Python code into the Python file.
- 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
No sketch libra...
Files
python
sketch
.gitignore
README.md
app.yaml
sketch.ino
- Upload: Click the Run button.
- Tilt the sensor — observe the event appear in both consoles.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
[2026-04-29 09:00:01] Arduino UNO Q SW520D Tilt Sensor Bridge ready
[2026-04-29 09:00:05] Tilt detected!
[2026-04-29 09:00:05] Upright again.
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
[2026-04-29 09:00:02] Tilt state: upright
[2026-04-29 09:00:03] Tilt state: upright
[2026-04-29 09:00:05] Tilt state: tilt
[2026-04-29 09:00:06] Tilt state: upright
Telegram
Receive instant Telegram alerts when tilt is detected on the Arduino UNO Q SW520D tilt sensor.
MCU sketch: Keep the same MCU sketch from the previous Bridge section.
Python Code (Telegram)
"""
This Arduino UNO Q script was developed by newbiely.com
This Arduino UNO Q script 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-sw520d-tilt-sensor
"""
from arduino.app_utils import *
import requests
import time
TELEGRAM_BOT_TOKEN = "YOUR_TELEGRAM_BOT_TOKEN"
CHAT_ID = "YOUR_CHAT_ID"
last_update_id = 0
def get_updates():
global last_update_id
url = f"https://api.telegram.org/bot{TELEGRAM_BOT_TOKEN}/getUpdates"
params = {"offset": last_update_id + 1, "timeout": 5}
try:
response = requests.get(url, params=params, timeout=10)
data = response.json()
if data["ok"]:
return data["result"]
except Exception as e:
print(f"Error getting updates: {e}")
return []
def send_message(chat_id, text):
url = f"https://api.telegram.org/bot{TELEGRAM_BOT_TOKEN}/sendMessage"
payload = {"chat_id": chat_id, "text": text}
try:
requests.post(url, data=payload, timeout=10)
except Exception as e:
print(f"Error sending message: {e}")
def loop():
# Auto-alert on new tilt detection
event = Bridge.call("get_event")
if event == "tilt_detected":
print("Tilt detected! Sending Telegram alert.")
send_message(CHAT_ID, "📐 Tilt detected by Arduino UNO Q!")
# Handle Telegram commands
updates = get_updates()
for update in updates:
last_update_id = update["update_id"]
if "message" not in update:
continue
message = update["message"]
chat_id = message["chat"]["id"]
text = message.get("text", "").strip()
print(f"Received: {text}")
if text == "/start":
send_message(chat_id,
"Arduino UNO Q SW520D Tilt Sensor Bot\n"
"/state - Current tilt state (tilt / upright)\n"
"Automatic alert when tilt is detected")
elif text == "/state":
result = Bridge.call("get_state")
send_message(chat_id, f"Tilt state: {result}")
App.run(user_loop=loop)
Detailed Instructions
- Replace YOUR_TELEGRAM_BOT_TOKEN with your actual bot token from BotFather.
- Replace YOUR_CHAT_ID with your Telegram chat ID.
- Paste this Python code into your App's Python file (keep the same MCU sketch).
- Click the Run button — tilt the sensor to trigger a Telegram alert.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
[2026-04-29 09:10:00] Waiting for Telegram messages...
[2026-04-29 09:10:05] Tilt detected! Sending Telegram alert.
[2026-04-29 09:10:10] Received: /state
Telegram
12:45
Welcome to Telegram!
ArduinoBot
10:19
Chatting with Arduino...
BotFather
Yesterday
Your bot has been created.
ArduinoBot
bot
OpenClaw
You can adapt the OpenClaw to this tutorial by refering the instruction on Arduino Uno Q - OpenClaw Tutorial
Project Ideas
You can build many useful projects with the SW520D tilt sensor and Arduino UNO Q:
- Anti-Tamper Alert: Attach the sensor to an enclosure — if it is tilted or moved, the MPU sends an immediate Telegram alert with a timestamp so you know when tampering occurred
- Tilt-Activated Switch: Use the tilt sensor with a relay via Bridge — Python detects the tilt event and toggles a light or fan on or off based on orientation
- Equipment Monitor: Mount the sensor on machinery or furniture — the MPU logs each tilt event to a CSV file on Linux and sends a Telegram report at the end of the day
- Smart Safe Alert: Combine the tilt sensor with a door sensor — Telegram alerts when either the safe door opens or the safe itself is moved
- RC Tilt Controller: Use two SW520D sensors mounted on different axes — the MPU reads both states via Bridge and sends orientation commands to control a remote device over Wi-Fi