Hey everyone! Are you looking to dive into the world of microcontrollers and want to start with something cool like measuring temperature? You've come to the right place! In this guide, we'll explore how to use the micro:bit's built-in temperature sensor and write some code to display the readings. Let's get started!

Understanding the Micro:bit Temperature Sensor

The micro:bit comes with a built-in temperature sensor, which is actually part of the microcontroller itself. It measures the temperature of the die (the silicon chip) inside the micro:bit. While this isn't exactly the ambient temperature, it can give you a reasonable estimate and is perfect for learning the basics. Keep in mind that factors like the micro:bit's processing load and surrounding components can influence the temperature reading. Therefore, for precise environmental temperature measurements, you might want to consider using an external temperature sensor.

How the Temperature Sensor Works

The temperature sensor in the micro:bit leverages the properties of semiconductors. As the temperature changes, the electrical characteristics of the silicon die also change. The micro:bit's internal circuitry measures these changes and converts them into a temperature value. The temperature is usually reported in degrees Celsius. This method is quite common in microcontrollers because it doesn't require any additional external components, making it a cost-effective and compact solution. However, as mentioned before, the accuracy can be affected by the heat generated by the micro:bit itself, especially during heavy processing tasks. So, if you are running complex programs, the temperature readings might be a bit higher than the actual ambient temperature. To mitigate this, you could take readings periodically and allow the micro:bit to cool down between measurements.

Considerations for Accurate Readings

To get the most accurate readings possible, there are a few things to keep in mind. First, avoid placing the micro:bit in direct sunlight or near other heat sources. These external factors can significantly skew the temperature readings. Second, be aware of the micro:bit's processing load. If the micro:bit is performing a lot of calculations or running complex algorithms, it will generate more heat, which can affect the temperature sensor. Try to minimize the processing load when taking temperature readings, or take readings periodically to allow the micro:bit to cool down. Third, consider calibrating the temperature sensor. You can do this by comparing the micro:bit's readings to a known accurate temperature source, such as a calibrated thermometer. If there is a consistent difference between the two, you can adjust your code to compensate for this difference. Finally, remember that the micro:bit's temperature sensor is not designed for high-precision measurements. If you need very accurate temperature readings, you should use an external temperature sensor specifically designed for that purpose. These sensors often come with their own calibration and error correction mechanisms, providing much more reliable data.

Setting Up Your Micro:bit Development Environment

Before we dive into the code, let's make sure your development environment is ready. You'll need a micro:bit board, a USB cable to connect it to your computer, and access to the MakeCode editor. The MakeCode editor is a web-based platform, so you don't need to install anything on your computer. Just head over to MakeCode for micro:bit.

Connecting Your Micro:bit

First things first, grab your micro:bit and the USB cable. Plug the micro:bit into your computer using the USB cable. Your computer should recognize the micro:bit as a removable drive. This is how you'll transfer your code to the micro:bit later on. If your computer doesn't recognize the micro:bit, try a different USB cable or a different USB port on your computer. Sometimes, the issue can be as simple as a faulty cable or a loose connection. Also, make sure that the drivers for the micro:bit are properly installed on your computer. In most cases, the drivers will be installed automatically when you plug in the micro:bit for the first time. However, if you encounter any problems, you can usually find the drivers on the micro:bit website or in the documentation that came with your micro:bit. Once your computer recognizes the micro:bit, you're ready to move on to the next step.

Navigating the MakeCode Editor

Once you're in the MakeCode editor, you'll see a block-based programming interface. On the left, you have a simulator that shows a virtual micro:bit. In the center, you have the blocks that you'll use to build your code. On the right, you have the code editor where you can see the equivalent JavaScript or Python code. Spend a few minutes exploring the different categories of blocks. You'll find blocks for basic input and output, logic, loops, variables, and more. The MakeCode editor is designed to be intuitive and user-friendly, so don't be afraid to click around and see what's available. You can also find tutorials and example projects on the MakeCode website to help you get started. If you're new to block-based programming, the tutorials are a great way to learn the basics and get familiar with the interface. And if you're already familiar with programming, you can switch to the JavaScript or Python view to write code directly.

Writing the Temperature Sensor Code

Alright, let's get to the fun part – writing the code! We'll create a simple program that reads the temperature from the micro:bit's sensor and displays it on the screen.

Initializing the Program

Start by creating a new project in the MakeCode editor. You'll see two default blocks: on start and forever. The on start block runs once when the micro:bit starts up, and the forever block runs continuously in a loop. We'll use the forever block to continuously read and display the temperature. Inside the forever block, we'll add the code to read the temperature and display it on the screen. This will ensure that the temperature is updated regularly. You can also add code to the on start block to initialize any variables or settings that you need for your program. For example, you might want to set the display brightness or clear the screen before starting the main loop. However, for this simple temperature sensor program, we don't need to do any initialization in the on start block.

Reading the Temperature

To read the temperature, go to the Input category and find the temperature (℃) block. Drag this block into the forever block. This block reads the current temperature from the micro:bit's built-in sensor and returns the value in degrees Celsius. You can also find other input blocks in the Input category, such as blocks for reading button presses, accelerometer data, and compass readings. These blocks can be used to create more complex and interactive programs. For example, you could use the button presses to trigger different actions based on the temperature, or use the accelerometer data to detect movement and adjust the temperature display accordingly.

Displaying the Temperature

Now, let's display the temperature on the micro:bit's screen. Go to the Basic category and find the show number block. Drag this block into the forever block, after the temperature (℃) block. Now, drag the temperature (℃) block into the show number block. This will display the current temperature on the micro:bit's screen. You can also use the show string block to display text along with the temperature. For example, you could display the text "Temperature: " before the temperature value. This would make the display more informative and easier to understand. The Basic category also contains other display blocks, such as blocks for displaying icons, scrolling text, and clearing the screen. These blocks can be used to create more visually appealing and informative displays.

Adding a Delay

To prevent the temperature from updating too quickly, let's add a short delay. Go to the Basic category and find the pause (ms) block. Drag this block into the forever block, after the show number block. Set the delay to 1000 milliseconds (1 second). This will cause the micro:bit to pause for one second after displaying the temperature, before reading and displaying the temperature again. You can adjust the delay to suit your needs. A shorter delay will cause the temperature to update more frequently, while a longer delay will cause the temperature to update less frequently. Keep in mind that a very short delay can cause the micro:bit to consume more power, while a very long delay can make the temperature display seem sluggish.

Complete Code

Here's what the complete code should look like:

forever(function () {
    basic.showNumber(input.temperature())
    basic.pause(1000)
})

Downloading and Running the Code

Once you've written the code, it's time to download it to your micro:bit and see it in action!

Compiling the Code

The MakeCode editor automatically compiles your code in the background. You don't need to do anything special to compile it. As you add and modify blocks, the MakeCode editor translates them into JavaScript or Python code, which is then compiled into a binary file that can be run on the micro:bit. You can view the generated JavaScript or Python code by clicking on the JavaScript or Python tab in the editor. This can be helpful for understanding how the blocks are translated into code and for learning more about programming in general. The MakeCode editor also provides error checking and debugging tools to help you identify and fix any problems in your code. If there are any errors, the editor will display a message indicating the type of error and where it occurred in the code. You can use this information to correct the error and recompile the code.

Downloading the Hex File

Click the "Download" button in the MakeCode editor. This will download a .hex file to your computer. The .hex file contains the compiled code that can be run on the micro:bit. The .hex file is a standard file format for storing compiled code for microcontrollers. It contains the machine code instructions that the microcontroller will execute, as well as any data that the program needs. The MakeCode editor automatically generates the .hex file when you click the "Download" button. You can also download the .hex file manually by clicking on the "Compile" button and then selecting the "Download .hex" option. This can be useful if you want to save the .hex file for later use or if you want to share it with others.

Flashing the Code to Your Micro:bit

Connect your micro:bit to your computer using the USB cable. Open the removable drive that represents your micro:bit. Drag and drop the .hex file onto the micro:bit drive. The micro:bit will start flashing, indicating that it's receiving the code. Once the flashing stops, the code is running on your micro:bit! If the micro:bit doesn't start flashing automatically, you may need to press the reset button on the back of the micro:bit. This will force the micro:bit to restart and load the new code. You can also use the MakeCode editor to flash the code to the micro:bit directly, without having to manually drag and drop the .hex file. To do this, click on the "Connect" button in the editor and follow the instructions to connect your micro:bit. Once the micro:bit is connected, you can click on the "Flash" button to flash the code to the micro:bit directly from the editor.

Viewing the Temperature

Now, look at the micro:bit's screen. You should see the temperature being displayed in degrees Celsius. The temperature will update every second. If the temperature readings seem inaccurate, remember the considerations we discussed earlier about the micro:bit's internal temperature sensor. The temperature displayed is the temperature of the micro:bit's die, not the ambient temperature. If you want to measure the ambient temperature more accurately, you should use an external temperature sensor. You can also try calibrating the temperature sensor by comparing the micro:bit's readings to a known accurate temperature source and adjusting your code to compensate for any differences. Finally, keep in mind that the temperature readings may fluctuate slightly due to variations in the micro:bit's processing load and surrounding environment.

Enhancements and Further Exploration

Congratulations! You've successfully created a temperature sensor using the micro:bit. Now, let's explore some ways to enhance this project.

Displaying a Temperature Scale

Instead of just showing the raw temperature, you could add a temperature scale to the micro:bit's screen. For example, you could use the LEDs to display a bar graph that represents the temperature range. This would give you a visual indication of how hot or cold it is. To do this, you would need to map the temperature range to the number of LEDs on the screen. For example, if the temperature range is from 0 to 50 degrees Celsius, you could map 0 degrees to 0 LEDs and 50 degrees to 25 LEDs (the maximum number of LEDs on the micro:bit's screen). Then, you could use the plot bar graph block to display the bar graph on the screen.

Adding a High/Low Temperature Alert

You could add code to trigger an alert if the temperature goes above or below a certain threshold. For example, you could make the micro:bit display a warning message or play a sound if the temperature exceeds 30 degrees Celsius or falls below 10 degrees Celsius. This could be useful for monitoring the temperature in a greenhouse or a refrigerator. To do this, you would need to use the if block to check if the temperature is above or below the threshold. If it is, you could use the show string block to display a warning message or the music blocks to play a sound.

Using an External Temperature Sensor

For more accurate temperature readings, consider using an external temperature sensor like the DHT11 or DHT22. These sensors provide more precise measurements and are less affected by the micro:bit's internal heat. You'll need to connect the sensor to the micro:bit's pins and use the appropriate library to read the data. The DHT11 and DHT22 sensors are relatively inexpensive and easy to use, making them a great option for more advanced temperature sensing projects. To use these sensors, you will need to connect them to the micro:bit's pins and use the appropriate library to read the data. There are several libraries available for the micro:bit that make it easy to interface with these sensors. You can find these libraries on the micro:bit website or in the MakeCode editor.

Conclusion

And there you have it! You've learned how to use the micro:bit's built-in temperature sensor, write code to display the temperature, and explore some enhancements. This is just the beginning – the possibilities with micro:bit are endless. Keep experimenting, keep learning, and have fun creating amazing projects!