Weather Station 1

In this project, we will use a micro:bit to measure a number of useful things, starting with temperature.
A micro:bit can measure temperature all on its own - try it!

It’s not very accurate - it might have an error of 4C.
Can we do anything about that?

Make measurements over one day

Now we will write code to make temperature measurements, and save them every 15 minutes for a whole day.
You can take the micro:bit anywhere to measure the temperature - but keep it dry!
We will read the measurements the next day, at about the same time. We could use them to plot a graph perhaps.
Our code will need a list to put the temperature readings in. We give it a name - templist.

A list is like a table:
 count temperature
 0 21
 1 21
 2 22
  
 95 25

Here is some code which saves the temperature to the list:


Let’s start coding!

In your Chrome browser, open the MakeCode website (makecode.microbit.org) and pair the micro:bit by clicking on the gear wheel, then Pair device.

Here is the code to make our measurements

We are using a variable called 15 minutes - the micro:bit timer uses milliseconds (1 second/1000) rather than minutes, so we convert 15 minutes to 15 x 60 x 1000 milliseconds.

We make 4 measurements an hour, so we need to run our loop 24 x 4 times.

Code to read out our measurements

This will display the count number and temperature.
Enter both of these code blocks.

Testing your code

You can speed up your code while you are testing by changing this block. Now your 15-minute timer runs 60 times faster!
⚠ Don’t forget to change back to 15 minutes and save it!
Now test your temperature readings over 1 day.

⚠You must keep the micro:bit switched on until you have finished reading out the data - otherwise your measurements will disappear!
  1. Start the measurements by pressing button A.
  2. The next day (at least 24 hours later), press button B to see the data.
You can write down the temperatures to use later.

Send your measurements to a computer (Windows)

You can save the data on a computer - to plot a chart for example.

⚠You must keep the micro:bit switched on all the time from when you start making the measurements (button A) until you have finished reading out the data (button B) - otherwise your measurements will disappear!
  • You will need an app (Tera Term) on your Windows laptop.
  • Connect your micro:bit to the laptop using a USB cable.
  • Open Tera Term, then click Serial and choose the Port which says USB:

  • Next, 
    • click OK then 
    • click on the Setup menu then
    • select Serial, then
    • Select 115200 under Speed
    • Finally, click OK
On your micro:bit click button B to send the data. You should see something like this:
You can save the data (using copy, then paste into a file) and convert it, using a spreadsheet, to a chart, like this:

Comments

Post a Comment

Popular posts from this blog

Air Quality Monitor

Image
Sensing air quality by measuring  the concentration of 2.5 μm particulates is a useful and fun thing to do. This project displays the measurement on a microbit, and it will be developed to also use a small LCD module. This is slightly more advanced than my usual microbit projects - it uses JavaScript rather than blocks, and involves some fiddly soldering. The inspiration comes from some fascinating internet chat and articles on how to adapt a low-cost Ikea monitor, the  Vindriktning . This cost £15 at the time of writing, which seems affordable for a school project. The device is a stand-alone small box, that has a simple LED indication to show green (good), yellow (ok), and red (not good). It's powered from a USB-C lead. The website for  Home Assistant  (free software for home automation) has a useful series of posts  on Vindriktning  here . These have focussed on adding a small device to log the air quality measurements. They have generally used an ESP8266 microcontroller which i
Read more

Low-cost solar power source for microbits

Image
  Solar panel, microbit, battery and regulator Update I have made a few improvements since this post was published in September 2022: The key change is to use a   separate low-dropout regulator (LDO) to provide the 3.3V supply to the microbit and other components. I had previously used the microbit's internal regulator. I found subsequently that it has a curious high-current region as the battery voltage drops, which leads to a period of rapid battery discharge.  AA rechargeable cells, with 1200 mAh capacity, replace the previous AAA 850 mAh cells I use a 2W solar panel and a smaller current limit resistor, so that I can get a higher charging current I added a PNP transistor to the output of the TL431 shunt, so that it can handle more than 100 mA These changes do add a little to the overall cost, but they do give more reliable operation under a wide range of solar input. Introduction This article describes a low-cost DIY solar power source which is aimed at school projects such
Read more

A better Real Time Clock

Image
 A better Real Time Clock The DS3231 RTC is much more suited to the micro:bit than the DS1302. That's because it is designed to work with 3V devices (the DS1302 backup wasn't very reliable at 3V).  Here are a few reasons why you might want "real" time on a microbit: if you are recording measurements ( data logging)  you probably want to record the time you made them - this is known as a  timestamp . if you are automating something, such as a security light, you might need to do things at a particular time. The microbit can measure  elapsed  time, which can be useful, but you need to know the date and time when you started the timer. You can use the data logging feature in MakeCode's editor but that (at the moment) doesn't make a timestamp, and your microbit would have to be connected to a computer running MakeCode. I want to run data logging without connecting to a computer, so that the microbit is a self-contained module. So adding a small Real Time Clock mod
Read more