Arduino UNO Q - Potentiometer
A potentiometer (also called a rotary angle sensor or variable resistor) lets you manually adjust a value by turning a knob. Common uses include controlling volume, brightness, and motor speed. In this tutorial, you will learn how to connect a potentiometer to Arduino UNO Q, read its ADC value, convert it to voltage, and check readings remotely via Telegram.
※ NOTE THAT:
Arduino UNO Q ADC difference: The STM32 MCU on Arduino UNO Q has a 12-bit ADC (values 0–4095), compared to the 10-bit ADC (0–1023) on many other Arduino boards. The reference voltage is 3.3V. Always use these values when converting ADC readings.
Hardware Preparation
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Overview of Potentiometer
Pinout
A potentiometer has three pins:
- GND pin: connect to GND
- VCC pin: connect to 3.3V (on Arduino UNO Q, the MCU operates at 3.3V)
- Output pin: connect to an analog input pin on the Arduino UNO Q
※ NOTE THAT:
The GND and VCC pins can be swapped — this reverses the direction of the output.
How It Works
Rotating the knob changes the resistance between the output pin and GND/VCC, which changes the output voltage proportionally:
- At 0° (GND side): output = 0V
- At maximum angle (VCC side): output = 3.3V (on Arduino UNO Q)
- In between: output = (angle / ANGLE_MAX) × 3.3V
Arduino UNO Q ADC
The Arduino UNO Q MCU (STM32U585) reads the output voltage through a 12-bit ADC — producing values from 0 to 4095:
| Source | Range |
|---|---|
| Knob angle rotated | 0° to ANGLE_MAX |
| Output voltage | 0V to 3.3V |
| ADC value read by Arduino UNO Q | 0 to 4095 |
| Mapped output value | VALUE_MIN to VALUE_MAX |
Common Conversions
- ADC to voltage:
voltage = floatMap(adc_value, 0, 4095, 0, 3.3);
- ADC to a controllable level (e.g. brightness 0–255):
brightness = map(adc_value, 0, 4095, 0, 255);
- ADC to angle (if ANGLE_MAX is known):
angle = map(adc_value, 0, 4095, 0, ANGLE_MAX);
※ NOTE THAT:
map() returns an integer. For floating-point conversions, use floatMap() as shown in the code below.
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
MCU Code — Potentiometer
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-potentiometer
*/
float floatMap(float x, float in_min, float in_max, float out_min, float out_max) {
return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
void setup() {
// nothing to set up
}
void loop() {
// Read ADC value from pin A0 (12-bit: 0-4095 on Arduino UNO Q)
int adc_value = analogRead(A0);
// Convert ADC value to voltage (3.3V reference on Arduino UNO Q)
float voltage = floatMap(adc_value, 0, 4095, 0, 3.3);
// TO DO: use adc_value or voltage in your logic here
// Example: map to a 0-100 scale
// int level = map(adc_value, 0, 4095, 0, 100);
delay(500);
}
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 potentiometer: Connect GND to GND, VCC to 3.3V, and the output pin to A0 according to the wiring diagram.
- 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_Potentiometer
- 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.
- Turn the potentiometer knob — the ADC value and voltage are read every 500 ms. Results are visible via the Bridge Monitor in the next section.
- Pro Tip: Replace the TO DO comment with map(adc_value, 0, 4095, 0, 255) to drive LED brightness via PWM.
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 potentiometer is connected to the MCU (STM32) — wired to an analog input pin (A0) on the STM32. The MCU reads ADC values and converts them to voltage.
- The MPU cannot read the potentiometer directly — it must request the reading from the MCU via Bridge.call(). The MCU responds with the current ADC value and voltage.
- The MPU has Wi-Fi — because the MPU runs full Debian Linux with Wi-Fi, it can report the potentiometer reading via Telegram on demand.
- Communication: Bridge.call() on the Linux side invokes Bridge.provide() functions on the MCU side
- ⚠️ Reserved: /dev/ttyHS1 (Linux) and Serial1 (MCU) are used by the Arduino Router — never open them directly
In short: MPU requests potentiometer reading → MCU reads ADC → MCU reports value and voltage → MPU logs or forwards it.
MCU sketch — potentiometer with Bridge and Monitor output:
/*
* 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-potentiometer
*/
#include "Arduino_RouterBridge.h"
float floatMap(float x, float in_min, float in_max, float out_min, float out_max) {
return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
void get_potentiometer() {
int adc_value = analogRead(A0);
float voltage = floatMap(adc_value, 0, 4095, 0, 3.3);
Monitor.print("ADC: ");
Monitor.print(adc_value);
Monitor.print(", Voltage: ");
Monitor.println(voltage);
}
void setup() {
Bridge.begin();
Monitor.begin();
Bridge.provide("get_potentiometer", get_potentiometer);
Monitor.println("Potentiometer Bridge ready");
}
void loop() {}
Python script (Arduino App Lab) — poll potentiometer from Linux:
/*
* 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-potentiometer
*/
from arduino.app_utils import *
import time
def loop():
while True:
Bridge.call("get_potentiometer")
time.sleep(1)
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 above 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 — the Python side polls the potentiometer every second.
- Turn the potentiometer knob and watch the ADC value and voltage update in real time.
- Check the console: Open the Console tab → MCU Monitor subtab.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
Potentiometer Bridge ready
ADC: 0, Voltage: 0.00
ADC: 820, Voltage: 0.66
ADC: 2048, Voltage: 1.65
ADC: 3275, Voltage: 2.64
ADC: 4095, Voltage: 3.30
Telegram Integration
Read the current potentiometer value remotely from anywhere 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 potentiometer reading:
/*
* 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-potentiometer
*/
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 == "/read":
reading = Bridge.call("get_potentiometer")
send_message(chat_id, reading)
else:
send_message(chat_id, "Commands:\n/read — read potentiometer ADC value and voltage")
time.sleep(1)
App.run(user_loop=loop)
- Note: Replace YOUR_BOT_TOKEN with the token obtained from @BotFather on Telegram.
- Send /read to trigger a potentiometer reading — the result appears in the MCU Monitor.
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: Turn the potentiometer, send /read — the bot replies with the ADC value and voltage.
App Lab Console Output
sketch.ino
1#include "Arduino_RouterBridge.h"
Serial Monitor
Python
[2026-04-29 12:00:01] Telegram: /read
[2026-04-29 12:00:01] ADC: 1234, Voltage: 1.00
[2026-04-29 12:03:20] Telegram: /read
[2026-04-29 12:03:20] ADC: 3072, Voltage: 2.48
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 potentiometer reading is coming soon.
- Coming Soon: OpenClaw support for potentiometer reading on Arduino UNO Q will be covered in a future update.
Application/Project Ideas
- Remote volume knob: Use a potentiometer to set audio volume — read the level remotely via Telegram
- Light level setter: Use a potentiometer to set an LED brightness target — check the set level via Telegram
- Motor speed selector: Map potentiometer value to motor speed — confirm speed via Telegram
- Threshold configurator: Use the potentiometer to set a sensor threshold (e.g. temperature alarm) remotely verifiable
- Calibration tool: Use the potentiometer to trim a sensor offset — check the calibration value via Telegram
Challenge Yourself
- Easy: Add a second output: map the ADC to a 0–100% level and print it alongside voltage
- Medium: Expose the potentiometer value as a percentage (0–100) via a get_level() Bridge callback
- Advanced: Build a Telegram bot that continuously monitors the potentiometer and sends a notification when the value changes by more than 10% from the last reading