Some links on this page are affiliate links: if you buy through them we may earn a commission, at no extra cost to you.
Connect an SHT40 breakout to an Arduino UNO R4 WiFi, then choose the graph that fits your project: Arduino IDE Serial Plotter for an immediate USB view, or an Arduino IoT Cloud dashboard for remote monitoring. The SHT40 supplies both temperature and relative-humidity readings over I²C, so you can plot either value or both.
The UNO R4 WiFi combines a 5 V RA4M1 controller with a separate ESP32-S3 module for 2.4 GHz Wi‑Fi and Bluetooth LE. It is therefore suitable for a connected graph, while Serial Plotter remains the quickest way to verify the hardware.
What you will build
- An SHT40 measures ambient temperature (and optionally humidity).
- The UNO R4 WiFi reads the sensor over I²C.
- A non-blocking sketch emits samples every few seconds.
- Serial Plotter displays a temporary local graph.
- Arduino IoT Cloud can publish variables to a remote dashboard, subject to the service’s current history and plan limits.
The onboard 12×8 LED matrix is useful for icons or a small numeric indicator, not for a practical time-series graph. See the UNO R4 WiFi documentation.
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →Parts and prerequisites
- Arduino UNO R4 WiFi
- SHT40 breakout or carrier board
- USB-C cable, breadboard and jumper wires
- Arduino IDE with the UNO R4 board package
- A 2.4 GHz Wi‑Fi network only if you use Arduino Cloud
Do not buy the bare SHT40 IC for breadboard wiring. The chip accepts approximately 1.08–3.6 V, whereas the UNO R4 WiFi’s RA4M1 and GPIO system are 5 V. Choose a carrier with accessible pins and clearly documented power handling, I²C pull-ups, and level shifting (or explicit 5 V-bus compatibility). Check the carrier’s requirements before connecting its VIN pin. Sensor specifications are listed by Sensirion and board electrical details in the UNO R4 WiFi datasheet.
#1 Best Overall
![Arduino UNO R4 WiFi [ABX00087] - Renesas RA4M1 + ESP32-S3, Wi-Fi, Bluetooth, USB-C, CAN, 12-bit DAC, OP AMP, Qwiic Connector, 12x8 LED Matrix for Advanced IoT & Embedded Projects](https://m.media-amazon.com/images/I/416S910MpBL._SL160_.jpg)
- Dual-Core Processing with Renesas RA4M1 and ESP32-S3: The Arduino UNO R4 WiFi combines the Renesas RA4M1 microcontroller (ARM Cortex-M4) and the ESP32-S3 Wi-Fi/Bluetooth chip, delivering powerful dual-core processing capabilities. This combination offers flexibility for a wide range of projects, from high-speed communications and wireless control to real-time data processing and edge AI applications.
- Comprehensive Wireless Connectivity: Equipped with Wi-Fi and Bluetooth 5.0, the UNO R4 WiFi ensures robust wireless communication for IoT projects, remote sensors, smart devices, and wireless control applications. Whether connecting to the cloud, other devices, or local networks, the board offers stable and high-speed wireless connectivity for seamless operation.
- Modern USB-C, CAN, & Qwiic Connector: The USB-C port enables efficient power delivery and fast programming, improving ease of use compared to traditional USB connections. The Controller Area Network (CAN) support allows for reliable, real-time communication in industrial, automotive, or robotic systems. Additionally, the Qwiic Connector makes it easy to add I2C sensors and peripherals, simplifying the connection process and reducing the need for complex wiring.
- High-Precision 12-bit DAC & OP-AMP: For projects that require high-quality analog output, the 12-bit DAC (Digital-to-Analog Converter) and integrated operational amplifier (OP-AMP) provide precise analog signal generation and amplification. This feature is ideal for audio projects, sensor interfacing, or applications where analog signal control and processing are necessary.
- Integrated 12x8 LED Matrix: The UNO R4 WiFi includes a built-in 12x8 LED Matrix, enabling users to display dynamic visuals, messages, or real-time data on the board itself. This makes it perfect for projects that require immediate visual feedback, such as status indicators, event displays, or interactive user interfaces.
Wire the SHT40
| SHT40 breakout | UNO R4 WiFi |
|---|---|
| VIN/VCC | Supply permitted by the breakout documentation |
| GND | GND |
| SDA | SDA |
| SCL | SCL |
The board also provides a Qwiic connector. A Qwiic SHT40 module and cable can reduce wiring mistakes, but I²C alone does not guarantee Qwiic voltage or connector compatibility; verify the module documentation. Product pin and connector information is available on the Arduino product page.
Check the I²C address first
The official Sensirion Arduino example uses 0x44. SHT4x variants can also use 0x45 or 0x46. Run an I²C scanner before changing application code; configure the library for the address that your scanner actually finds.
Install the IDE and library
- Install or update Arduino IDE.
- Open Boards Manager, install the Arduino UNO R4 package, and select Arduino UNO R4 WiFi.
- Select the USB serial port for the board.
- Choose Sketch → Include Library → Manage Libraries….
- Install Sensirion I2C SHT4X.
- Open the library’s
exampleUsageexample, upload it, and open Serial Monitor at 115200 baud.
The library’s source and examples are at Sensirion’s arduino-i2c-sht4x repository. Library APIs can change, so compare the method signature with the version installed in your IDE.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Rank #2
- All-in-One Starter Kit for Arduino Beginners: The Kit features the original Arduino Uno R4 WiFi board, 300+ high-quality components, and 60+ free video lessons co-created with educator Paul McWhorter. With over 50 projects (30 basic, 13 fun, and 8 IoT), it's perfect for beginners aged 8+ to explore Arduino. Certified RoHS compliant, it ensures safety and quality for all learners.
- Powerful Arduino Uno R4 WiFi Board: Upgraded from the Arduino Uno R3, the Arduino Uno R4 WiFi features a 32-bit processor, more memory, and built-in WiFi and Bluetooth, enabling connection to third-party apps for more interactive and practical projects.
- 300+ Components for Endless Possibilities: With 300+ components and sensors, this kit is perfect for portable projects. It features step-by-step tutorials, open-source code, and compatibility with other Arduino boards like Uno R3 and Nano, offering endless customization and learning opportunities.
- Engaging Projects for Every Skill Level: Featuring 50 projects (30 basic, 13 fun, 8 IoT) with IoT app integration like Arduino IoT Cloud , this kit supports Arduino C++ programming, making it perfect for students, teachers, and engineers to learn, code, and create at any skill level.
- Dedicated Support for Beginners: Alongside online resources and video tutorials, SunFounder provides technical support and troubleshooting forums to help beginners solve programming challenges with ease.
Make a local Serial Plotter graph
This sketch samples every two seconds without blocking the processor. It prints temperature and humidity as two tab-separated numeric fields:
#include <Wire.h>
#include "SensirionI2cSht4x.h"
SensirionI2cSht4x sht4x;
const unsigned long SAMPLE_INTERVAL_MS = 2000;
unsigned long lastSample = 0;
void setup() {
Serial.begin(115200);
delay(1000);
Wire.begin();
sht4x.begin(Wire);
Serial.println("temperaturethumidity");
}
void loop() {
unsigned long now = millis();
if (now - lastSample < SAMPLE_INTERVAL_MS) return;
lastSample = now;
float temperature = 0.0;
float humidity = 0.0;
uint16_t error = sht4x.measureHighPrecision(temperature, humidity);
if (error) {
Serial.print("SHT40 error: 0x");
Serial.println(error, HEX);
return;
}
Serial.print(temperature, 2);
Serial.print('t');
Serial.println(humidity, 2);
}After uploading, open Serial Monitor at 115200 and confirm plausible values. Then open Tools → Serial Plotter, select 115200, and watch the traces. Warm the sensor gently with a finger or move it to another room to create a visible change. For a temperature-only plot, replace the two output lines with Serial.println(temperature, 2);. Keep diagnostic text out of the data stream when plotting; some IDE versions handle labels differently, so verify the display with the IDE version you use.
What accuracy and response should you expect?
Sensirion specifies typical SHT40 temperature accuracy of ±0.2 °C, relative-humidity accuracy of ±1.8% RH, and a typical temperature response of about two seconds. Those are sensor specifications, not a guarantee for a complete breadboard assembly. The UNO’s regulator, USB connector, ESP32-S3 activity, airflow and enclosure can all bias or slow the observed graph.
Rank #3
- ELEGOO UNO R4 WiFi Control Board: Fully compatible with Arduino IDE and original Arduino shields. Features a 32-bit 48 MHz Renesas RA4M1 processor, USB-C, a 12 × 8 LED matrix, a Qwiic connector, built-in Wi-Fi and Bluetooth connectivity. Suitable for interactive STEM projects, it gives learners more room to progress from basic circuits to connected IoT projects
- Step-by-Step Tutorials for Beginners: Start with clear wiring diagrams and ready-to-run sample code, then advance through sensors, displays, motors, RFID, and wireless projects. Structured lessons reduce setup confusion and help beginners understand both how each circuit works and how to modify it
- 200+ Components with Practical Modules: Ultrasonic sensor, PIR motion sensor, RFID module, OLED display, keypad, joystick, relay, servo, stepper motor, DC motor and fan blade, temperature and humidity sensor, breadboard, jumper wires, LEDs, resistors, and more. Also compatible with your existing UNO R3 shields and projects
- Build Projects You Can Recognize: Equipped with professional online tutorials and step-by-step graphical manuals. Suitable for teens, beginners, hobbyists, educators, engineering students and electronics enthusiasts. The included parts support a progressive path from first coding exercises to maker prototypes without purchasing every module separately
- Organized Parts and Reliable Support: Each kit includes clearly listed components and beginner-friendly project resources to help users identify parts and start faster. ELEGOO provides responsive technical support for setup, programming, wiring and troubleshooting, ensuring you have a smooth learning experience
For room monitoring, a two-to-five-second interval is a practical starting point. Faster sampling creates denser data without overcoming the sensor’s physical response; longer intervals reduce network traffic. Celsius is the library’s native unit. Convert only for presentation when needed: float fahrenheit = temperature * 9.0 / 5.0 + 32.0;.
Build a remote Arduino Cloud graph
Use this route when you need to view the project away from the USB-connected computer. The UNO R4 WiFi is listed as an Arduino Cloud-compatible board; setup details can change, so confirm current labels and plan limits in Arduino’s documentation.
- Sign in to or create an Arduino account.
- Create an Arduino Cloud Thing and associate an UNO R4 WiFi device.
- Add a floating-point
temperaturevariable. Addhumidityif desired, and set device-published variables to read-only from the dashboard. - Add a chart widget and bind it to the variable or variables.
- Open the generated sketch, enter Wi‑Fi details as requested, and upload it.
- Keep the board powered and within range of a 2.4 GHz access point; confirm that new points arrive.
Cloud dashboards provide remote visualization, but “historical” does not mean guaranteed permanent, lossless storage. Retention, refresh behavior and widget options depend on the current Arduino Cloud service and plan. See supported devices, Cloud-compatible boards, and Arduino’s UNO R4 WiFi Cloud announcement.
Rank #4
![UNO R4 WiFi Board [ABX00087] – Dual-Core Microcontroller, Wi-Fi & Bluetooth, USB-C, CAN, 12-bit DAC, OP-AMP, Qwiic Connector, LED Matrix for IoT & Embedded Projects, Compatible with Arduino IDE](https://m.media-amazon.com/images/I/51ZSNygIuGL._SL160_.jpg)
- ⚡Dual-Core Power for Advanced Projects: The UNO R4 WiFi Board features the Renesas RA4M1 microcontroller combined with ESP32-S3, providing dual-core performance for real-time processing, wireless control, IoT applications, and edge AI projects.
- 📶 Seamless Wireless Connectivity: Integrated Wi-Fi and Bluetooth 5.0 enable reliable wireless communication for IoT devices, remote sensors, smart home automation, and industrial projects, ensuring stable connections to the cloud, networks, and other devices.
- 🔌 Modern Interfaces and Expandability: USB-C port allows fast programming and efficient power delivery. The CAN interface supports real-time communication in robotics, automotive, and industrial systems, while the Qwiic connector simplifies integration of I2C sensors and peripherals.
- 🛠️ High-Precision Analog Control: Equipped with a 12-bit DAC and built-in operational amplifier (OP-AMP), the UNO R4 WiFi Board delivers accurate analog signal generation and amplification, perfect for audio projects, sensor interfacing, and analog signal processing.
- ⏱️ Built-in 12x8 LED Matrix for Visualization: The onboard 12x8 LED matrix enables immediate visual feedback, making it ideal for displaying dynamic data, messages, interactive user interfaces, status indicators, or real-time project monitoring.
Connected-sketch considerations
Use millis() timing rather than a long blocking delay(), so Wi‑Fi and Cloud servicing can run. Assign Cloud variables only after a successful sensor read, and expose an error flag or diagnostic message so a flat chart is not mistaken for a constant temperature. A Wi‑Fi outage, reset, inadequate power or cloud interruption can create gaps; the board cannot upload measurements it never buffered.
Place the sensor for a useful graph
- Keep the sensing element away from the UNO regulator, ESP32-S3 module and USB connector.
- Do not cover it with tape or glue, and avoid touching it during normal sampling.
- Allow the board and sensor to reach thermal equilibrium.
- Avoid direct sun and unintended fan airflow.
- For permanent installations, use a ventilated enclosure.
The SHT40 operating specification spans −40 to 125 °C and 0–100% RH, but those limits do not make an ordinary breakout or Arduino assembly suitable for those extremes. The sensor heater intentionally changes the thermal environment and should not be enabled for routine logging; heater procedures are documented in the SHT4x datasheet.
Free tools Windows power users keep installed
One-click scans. No signup required.
Troubleshooting
No I²C device appears
- Verify common ground.
- Confirm SDA and SCL are not swapped.
- Check the breakout’s supply voltage and pull-ups.
- Run a scanner and note whether the address is 0x44, 0x45 or 0x46.
- Confirm the part and library are actually SHT4x/SHT40.
Values are implausible
Move the sensor away from board heat, open a sealed enclosure, stop touching the sensing area, and check for condensation. An incompatible carrier voltage arrangement or wrong sensor library can also produce failures. Do not interpret the ±0.2 °C typical specification as system accuracy.
Best Value
- [DUAL-CORE ARCHITECTURE FOR ADVANCED IOT] Built with a 32-bit Renesas RA4M1 and an ESP32-S3 coprocessor, this board handles heavy data processing and edge AI tasks effortlessly. It solves the computing bottlenecks of 8-bit boards, providing makers and developers with unprecedented power for complex smart home projects.
- [SEAMLESS WI-FI & BLUETOOTH 5.0 INTEGRATION] Equipped with native Wi-Fi and Bluetooth connectivity, eliminating the need for bulky external wireless shields. Ideal for remote sensor monitoring or cloud-based IoT networks, it offers stable, high-speed data transmission to keep your smart devices constantly connected.
- [BUILT-IN 12x8 LED MATRIX FOR INSTANT VISUALS] Features an integrated 12x8 red LED matrix directly on the board to display animations, scrolling text, or real-time sensor data. This provides engineers with immediate visual feedback and debugging capabilities without requiring any complicated external wiring.
- [MODERN INTERFACES: USB-C, QWIIC & CAN BUS] Upgraded with a robust USB-C port for fast programming, a Qwiic I2C connector for plug-and-play sensor addition, and built-in CAN bus support. These industrial-grade connections empower you to build automotive robotics or scalable systems safely and easily.
- [12-BIT DAC & ULTIMATE SHIELD COMPATIBILITY] Offers a high-precision 12-bit DAC and operational amplifier for premium analog audio projects. While significantly upgraded, it maintains the classic 5V operating voltage and form factor, ensuring your existing shields and modules remain fully compatible and useful.
Serial Plotter is blank
- Select the correct port and 115200 baud.
- Ensure numeric values are printed repeatedly.
- Remove verbose error text from the plotting stream.
- Close Serial Monitor if your IDE will not open both tools simultaneously.
Wi‑Fi or Cloud fails
Check 2.4 GHz availability, credentials, router security compatibility, board-package and Wi‑Fi-library versions, antenna range and stable power. In Cloud, verify that the Thing references the intended device and that the chart widget is bound to the variable being updated.
Which graphing method should you choose?
| Need | Best choice | Trade-off |
|---|---|---|
| Fast classroom demo or debugging | Serial Plotter | USB-connected and temporary |
| View from another room or device | Arduino Cloud dashboard | Requires account, Wi‑Fi and service configuration |
| Guaranteed long-term archive | Cloud plus an explicitly configured external logging system | More software and storage work; Cloud retention alone must not be assumed |
Alternatives and upgrades
An UNO R4 Minima is sufficient for USB Serial Plotter but lacks the UNO R4 WiFi’s built-in wireless capability (Arduino UNO R4 family). The compact Arduino Nano ESP32 is another Wi‑Fi-capable option when native ESP32 development and size matter more than the UNO form factor, 5 V shield ecosystem, Qwiic connector and LED matrix; Arduino’s Cloud-compatible-board page showed store prices of $18.30, or $19.30 with headers, when observed.
SHT41 and SHT45 sensors share the SHT4x family. A higher-rated sensor may be worthwhile for measurement work, but its difference may not be visible in an ordinary room graph. A custom web server on the UNO can avoid Cloud accounts, at the cost of writing the web interface, buffering data and handling networking yourself.
The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →The Bottom Line
Start with the SHT40 breakout, an I²C scan and the Sensirion example, then use Serial Plotter to prove the measurement path. Add Arduino Cloud only when remote viewing justifies the extra Wi‑Fi, account and service dependencies.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
