In this tutorial I'm going to show you how to count claps and display the total on the built in LEDs.
First of all you will need to make sure that you have a Micro:Bit V2 as this code needs a microphone to listen for the claps and the older Micro:Bit didn't have a microphone so won't work with this code. If you are not sure which Micro:Bit that you have then check out the section below "Which Micro:Bit do I have?"
Now open MakeCode (https://makecode.microbit.org/) and create a new project by clicking the New Project button.
Once you click the New Project button you will see a popup asking you to give your project a name (see pic below). I have called mine clap_counter but you can call yours whatever you like. Notice the smiley faces, these will start appearing as you type your project name name the more you type the more faces appear, well up to 3 anyway, this is to show you that longer names for projects are better than short names, if you imagine when you have a few projects how hard it might be to find the one you want if all your projects have five letter names. So basically name your project using a few words which describe it and that will help find it again later on.
Now we have a brand new project. You will see an "on start" and a "forever" loop, leave these there as we will be using both of them.
We will start with the on start block as we need to set a few things up. First we need to create a variable to hold the number of claps that have been counted. To do this first click 
and then 
, you will now be asked to name your variable, type in clapCount and click 
. Now you will see that in Variables there are three new items, 
, 
and 
. Drag the set clapCount to 0 and drop it in the "on start" block.
Now we need another variable, this time to hold the time that the Micro:Bit hears a clap. Click and then , you will now be asked to name your variable, type in lastClapTime and click . Now go back to , drag the 
block and put it into the "on start" block.
Go to 
then 
and drag the 
on to the and drop it so it replaces the 0. The is the time that the last event happened, events can be the pressing of a button, shaking the Micro:Bit or in this case the event will be when a loud noise is heard.
We now need to write some code to listen for the claps. We will listen for claps and when we hear the first clap or a clap less than 1 second after the last clap then we will add one to our clap counter. If we don't hear a clap within 1 second then we will display the number of claps that we have counted.
From 
drag an 
block onto the scripts area and place it below the last block in the on start block.
Drag an if then else block into the on loud sound block
From 
drag a 
block into the if then else. Replace the first 0 with and the second 0 replace with 
, you will find this in 
. Replace the first 0 of the with 
and in the second type 1000000 (this number is the amount of times the Micro:Bit counts in one second so if you wanted it to be 30 seconds you would use 30000000). The if statement now looks like this
The IF statement is basically saying that if the time that it heard a clap is less than (<) a second after the last recorded clap time then do this, we will now add code here to set the LastClapTime to now which is the time of this clap and add 1 to the ClapCount variable.
From drag a and place it in the space below the if. Right mouse click on one of the [event timestamp] blocks and Duplicate it, now drag the duplicate and place it over the 0 so the whole block now reads set LastClapTime to event timestamp.
From drag a and place it in the if statement below the last block that you placed down.
Now we need to put some blocks in the else part of the block. The blocks in the else part of this are run if the last clap was longer than 1 second ago, so this will be the first clap, either the Micro:bit has just been turned on or if the last clap was more than a second ago then the count starts again from 1.
In the if part of the block right mouse click on the set LastClapTime to event timestamp and duplicate it, make sure that the whole block has been duplicated and if so drag it to the space under the else.
From drag a block and place it in the else space under the last block that you placed in there, change the number to be one.
The whole of "on loud sound" set of blocks should now look like this
That takes care of counting the claps if they are within 1 second of each other, now we need to write some code to display the clap count if there is no clap for more than a second and set the clap count back to zero ready to count the next set of claps.
We now want to start adding blocks to the Forever Loop. Inside the forever loop the first thing that we need to do is to check if any claps have been counted, if no claps have then we don't need to do anything as there is nothing to show. To do this first add an "if then" block from the section, drag a comparison block also from the Logic section and place that in between the if and the then replacing the [true] part of the block. The comparison that we need is a > (greater than), if it is not a > then click the down arrow on the comparison block and change it to >. We now have "if 0 > 0 then" which doesn't make much sense as zero will never be greater than zero, lets sort that out now. From the section drag a over to the if statement and replace the first 0, we now have "if ClapCount > 0 then" which makes more sense as if any claps have been counted then ClapCount will be more than 0. Good!
We now need to use a slightly more advanced block, it might look a bit scary but I will explain what it does and hopefully once you've used it you'll see that it's not scary at all 🙂 Click on the section which will expand to show more sections, now go to the section, in here you will see a big block that starts with the words "raise Event", drag this block into the if then statement that we have just set up. This block will do what it says which is raise an event, an event in Micro:Bit terms is a button being pressed , the Micro:Bit being tilted (an accelerometer event), the Micro:Bit hearing a loud noise and so on. The reason that we need this is that the that we have been using only records when the last event happened, we now want to check if the time right now is longer than 2 seconds after the time of the last recorded clap, if it is then we will show the number of claps that we've counted and reset the count to zero so we can count another set of claps. To get the current timestamp we will in the raise event block set the "from source" to 
, this means that our event is going to be something to do with the A + B buttons, then you will set the "with value" to be 
. this block is now telling the Micro:Bit that something is happening with the A + B buttons (from source), that something that is happening is that the A+B buttons are clicked (MICROBIT_BUTTON_EVT_CLICK). So even though we have not just pressed the A+B buttons we have told the Micro:Bit that they have been, this means that we have just caused an event to happen and so the Micro:Bit will update the current event time in the .
Below the raise event block now add another if then block from the Logic section, as in the above if then block replace the [true] condition with a [0 > 0] comparison block. Replace the first 0 with the [event timestamp] block and the the second with a [0 + 0] block from the section. Drag a block from the section and replace the first 0 of the 0 + 0 block, then change the second 0 to be 2000000, this is 2 seconds in Micro:Bit time. So this if block is now saying that if now (event timestamp) is more than (>) 2 seconds after the last clap (LastClapTime + 2000000) then do what is inside this block which we will put in now.
In this if block we want to show the clap count and then reset it so that the count starts at zero again. First lets show the clap count, drag a 
block from the 
section and drop it into the if block. Grab a block from the section and place it over the "Hello!" text in the show string block. We want to leave the clap count showing for a short time so now drag a 
block and place this under the show string block, set the value to 1500. After this pause for 1.5 seconds we now want to clear the screen so drag a 
block from the section and place it below the pause block. All that's left to do now is to add a block from the below the clear screen block.
The finished forever loop should now look like this
Now there is only one thing left to do, we have placed the raise event block in the forever loop which will raise the event of pressing the A+B buttons, however, and I fell into this trap, the event will not be raised unless there is a on button A+B pressed. The on button A+B pressed can be empty but it must be there so drag an on button A+B pressed from onto the stage and that is it complete.
Here is what the whole project should now look like. Now connect your Micro:Bit and download the code. Once the code is downloaded you can run the program either connected to the computer or connected to a battery meaning you can take the Micro:Bit round with you.
When the program is running all you have to do is clap multiple times and then pause, the Micro:Bit will then display how many times you have clapped.
I hope you have fun with this. Can you use this code in a project that you have planned, maybe connect the Micro:Bit to some LEDs, clap once to turn them on or off, clap twice to turn them blue and three times to turn them red. If you use this code then please comment below and let me know what you did with it, I'd love to hear from you. Also if you have any questions about the code or you have a better way of doing it then comment below.
Until the next time, keep coding!