MakeCode automatically saves programs on the device that you are using. However, these programs may be deleted if your browser history is deleted. This module will describe ways to save a program more permanently or share it with another person.

Instead of downloading a program’s .hex file to the Finch, you can download it to your computer or Chromebook. After clicking Download, select the location where you want to save the .hex file and click Save. You can then email the file, store it on a USB drive, or treat it as you would any other file.

To load a file that you have saved in a .hex file, click on the Home button in MakeCode. From the home screen, click on the Import button.

Click on Import File.

Click on Choose File and navigate to the file you saved. Select it and then click Go ahead! Your file will open in MakeCode.

To share a file, click on the Share button in MakeCode

Click Publish Project.

MakeCode will show you a link that you can share with others. Alternatively, you can also click Embed to see code to embed your project in a website.

If you have two or more Finches, they can communicate by sending messages to each other! This means that you can make your Finches interact with each other. In this module, you will learn how to send and receive radio messages with the Finch. You can use this to make two Finches do the same movements at the same time.

In this module, there are two Finches: the sender, and the receiver. 

Start by creating a program for the sender Finch. To send a message you will use the blocks in the Radio menu. 

When using Radio blocks, the on start block should contain a radio set group block. In order to send and receive messages, two (or more) Finches must be set to the same radio group. Set the radio group number for the sender Finch to some number. If you are working in a room with other people using radio control, make sure that everyone chooses a different number.

The Finch can send a message using the radio send string block on the Radio menu. For example, this code sends the message “forward” when you press button A and then moves the sender Finch forward 20 cm.

Now it is time to program your second Finch, the receiver Finch. First, the receiver must be set to the same radio group using the radio set group block on the Radio menu.

Next, the receiver Finch can get a message using the on radio received block. This block listens for commands that are text instead of numbers; make sure to use the block that says receivedString. For example, this code moves the receiver Finch forward when it receives any text. If you want to make the receiver Finch do different things when it receives different messages, you can do this with an if else block, which you will learn about in the Boolean Data and Conditional Statements modules in Inputs.

CHALLENGE:

Try out the code above and make both Finches move forward when you press button A on the sender Finch. Then modify the code for both Finches so that they perform a synchronized dance when you press button A on the sender Finch.

Click Here to see example code.

The Finch menu contains two encoder blocks. The Finch Encoder block measures the number of wheel rotations that the wheel has moved since it was last reset. Before the Finch makes a movement that you want to measure, you need to use the Finch Reset Encoders block. This block sets both encoder values to zero. 

As an example, this code measures the number of rotations of the right wheel when the Finch moves forward for one second. 

Try out the code above. What happens when you set the wheel speeds to -75%?

You can also make the Finch move until the right or left encoder reaches a particular value. For example, this program resets the encoders when you press button A, and then moves the Finch forward until the right wheel has moved two rotations. Then the robot stops.

Note: This program uses an empty while loop. Empty while loops are useful structures for waiting on something to happen – in this case, for waiting until the encoder value is 2 or more before stopping the Finch.

Try out the program above. Then modify this program to make the robot move backward for two wheel rotations.

Click Here to see example code.

The diameter of a Finch wheel is 5 cm. To find the circumference, the distance around the wheel, you multiply this diameter by ????, which is approximately 3.14. This means that for one rotation, a Finch wheel moves about 15.7 cm.

To find how many rotations it will take to move a given distance, you can divide that distance (in centimeters) by 15.7. For example, it will take about 1.9 rotations for the Finch to move 30 cm.

Modify the program from the previous step to make the Finch move forward 50 cm. You are writing your own version of the code inside the Finch Move block!

Click Here to see example code.

You can also use the encoders to make the Finch measure a distance. For example, this program measures how far the Finch has to travel to find an obstacle. When you press button A, the encoders are reset. Then the Finch moves until an obstacle is less than 20 cm away. Finally, the robot stops and displays the number of rotations that the right wheel has traveled.

Try out the program above, then modify this program to display the distance in centimeters that the robot has moved. Hint: You will need a math block from the Math menu. Can you modify this program to measure the distance that the Finch has to travel to find a black line?

Click Here to see example code.

For this lesson, you will need large sheets of white paper and black electrical tape about 2 cm wide. Use the tape to make a black line on a white background. Avoid sharp turns; it is easier for the Finch to follow gradual curves.

To track a line, the Finch should turn right or left based on whether or not it detects the line. Let’s think about tracking the left side of the line with the left line sensor as the Finch moves clockwise around the loop. When the left line sensor is over the black line, the Finch should turn left. When the left line sensor is over the white surface, the Finch should turn right. 

Notice that this sample code uses the Finch Wheels block to turn using only one wheel at a time. This means that both turns move the robot slightly forward. As the Finch repeats the if else block over and over, it will follow the line as it turns back and forth.

Try out this code. You may need to adjust the line sensor threshold and the turning speed to track your line. Remember, the Finch needs to turn slowly.

Your current code works if you want the Finch to keep tracking the line forever. But what if there is an obstacle in the Finch’s path? Then you don’t want to repeat the if-else forever. You only want to repeat it as long as there is no obstacle. The while loop block from the Loops menu can help you here!

For example, when you press button A, this program makes the Finch blink its beak as long as the Finch is level. When the Finch moves out of the level position, the beak stops blinking. 

CHALLENGE

Use a while loop to make the Finch track your line until it finds an obstacle. The Finch should start tracking when you press button A. The Finch should stop when it finds an obstacle. 

Click Here to see example code.

As you build more complex programs, you will sometimes want to make decisions based on more than one sensor. For example, you might want to turn on the Finch beak and tail only if both light sensors detect that it is dark. To do this, you can use the logical operators on the Logic menu. These operators are Boolean blocks that contain spaces for other Boolean blocks. The and block is true if both blocks inside it are true and false if either block inside it is false. The or block, on the other hand, is true if either block inside it is true. The or block is only false when both blocks inside it are false. The not block is the opposite of the block inside it. It is true when the block inside is false and false when the block inside is true.

As an example, this program will turn the Finch beak and tail lights off and then waits for as long as either light sensor value is greater than 10. When that is no longer true (both light sensors values are less than 10), the lights will turn blue.

CHALLENGE

Modify your line tracking program to track the line as long as there are no obstacles and the Finch is not in the Beak Up position.

Click Here to see example code.

By using logical operators and all of the control structures that you have learned, you can create complex behaviors for the Finch. You can also use multiple control structures and nest blocks inside one another to get the behaviors you want. In addition, you can press the + button at the bottom of the if else block to add more Boolean conditions to the block. The block will check each Boolean condition in sequence. If a Boolean condition is true, it will execute the statements for that condition and move on to the next statement below the if else block. If none of the Boolean conditions are true, the statements inside the else will be executed.

For example, what do you think this code will do? Think carefully and make a prediction, and then try it out!

CHALLENGE

Turning left or right based on a single line sensor is the simplest version of a line tracking algorithm, but there are many variations. Write a program to implement the alternate line tracking algorithm described below. Which works better for your path?

• If the left line sensor is over white and the right is over black, turn right.
• If the right line sensor is over white and the left is over black, turn left.
• If both line sensors are over the same color, move forward in a straight line.
• For an extra challenge, modify your program to make the robot automatically restart tracking the line when you remove the obstacle!

Click Here to see example code.

The pick random block is on the Math menu in MakeCode. This block randomly chooses a number between the two limits given. For example, this block generates a number between 0 and 10. Each time the program runs the block, it will give you a different number.

You can use the pick random block anywhere that you would use a number in your program. For example, this program sets the speed of each wheel to a random number every two seconds. Notice that each wheel gets a different random number, so the Finch will mostly turn but sometimes move straight.

CHALLENGE

Use the pick random block to set the Finch’s beak and tail to different random colors.

Click Here to see example code.

You can also use a random number within a control structure. For example, this program will make the Finch beep a random number of times from 1 to 5.

CHALLENGE

Make the Finch play a random number song! The Finch should play a random number of notes, and each note in the sound should be random. 

Note: While the play tone block shows a computer keyboard when you select a note, this block can also take a note as a number from 20 to 20000.

Click Here to see example code.

To create a variable in MakeCode, go to the Variables menu and then click Make a Variable.

Give your variable a name. You should choose a name that describes what your variable is. In this case, let’s name our variable randomSpeed.

Notice that the Variables menu changes once you have created a variable. You will see a block with your variable name, as well as a set block and a change block.

You can use the set block to assign a value to your variable. If you have multiple variables, use the drop-down menu to select the one you want to set. In this example, the loop sets the variable randomSpeed equal to a random number between -100 and 100. It resets the value of the variable every two seconds.

To use the variable value, drag the block with the variable name into your program. You can use randomSpeed anywhere you would use another number block in MakeCode. For example, you can use it to set the speeds of both Finch motors. You can also use the show number block to see the value of the variable on the screen. Notice that in this program, only the set block changes the value of randomSpeed. The randomSpeed block just fetches this number and uses it within the show number and Finch Wheels blocks. That means you can be sure that both wheels will have the same speed.

CHALLENGE

Create three variables named red, green, and blue. Use these variables to set the color of the Finch’s beak and tail to the same random color. The color of the beak and tail should change once per second.

Click Here to see example code.

You can use the change block to modify the existing value of a variable. For example, this program sets blue to 0 at the top of the program and then adds 1 to blue each time through the loop. What will the value of blue be at the end?

You can use a loop like this to gradually change the value of a Finch output. For example, you can use blue to gradually increase the brightness of the Finch beak. You can even use a math block from the Math menu to make the R value for the Finch beak go from 100 to 0 as the B value changes from 0 to 100. What do you think will happen when you run this code?

CHALLENGE

Modify the code above by adding another repeat block below the existing one. Use this repeat block to gradually change the value of blue from 100 back to 0.

Click Here to see example code.

MakeCode also contains a loop called a for block. This loop creates a variable called index that automatically changes from 0 to the value specified in the loop. Each time through the loop, the value of index automatically increases by one. This means that this program also gradually changes the Finch beak from red to blue! 

CHALLENGE

Modify your code for the Step 4 challenge to change the LED color in the same way as in Step 4, but using for loops.

Click Here to see example code.

Any time you need to use the same value more than once in a program, you can use a variable. Variables are also helpful if you may need to change a value later. For example, this program has two loops that use a threshold for the light sensor. One controls the Finch beak, and one controls the Finch buzzer. Depending on the amount of light in the room, you may have to adjust the value of the threshold in the future. This is a great opportunity to use a variable! Notice that we only set the value of the threshold variable once, at the very beginning of the program. If we need to change the threshold in the future, we will only need to change it in one place.

CHALLENGE

Write a program that does the following:

• The Finch should move forward until it is 10 cm from the wall.
• Then the Finch should back up until it is 30 cm from the wall.
• Then the Finch should move forward until it is 20 cm from the wall. 
• All of these movements should be made using a variable named distanceThreshold that is equal to 10 cm. Your program cannot contain the numbers 20 or 30. Hint: You need to use math blocks!

What will your program do when you change distanceThreshold to 20?

Click Here to see example code.

Start by going to the Arrays menu in the Advanced section of the menu list. You will see two set blocks, one for numbers and one for text. 

Drag the set block for numbers into your on start block. By default, this block uses a variable named list. Give your array a more informative name by clicking the drop-down menu and selecting Rename variable. Change the name of your array to noteArray and click OK.

The first step is to add some values to your array. For example, this code creates an array that contains two values, 300 and 400. You can add or remove values from the array using the + and – buttons in the set block.

CHALLENGE

Use this script to add 5-10 different values to noteArray. All the values should be numbers from 262 to 988.

Click Here to see example code.

To access the data within an array, you can use the for element block from the Loops menu.

Drag the for element block into a forever loop and select noteArray in the drop-down. This loop will move through your array. Each time through the loop, the variable value will be set equal to the next number in your array.

Consider this example code. When you press button A, the for element block sets value equal to the first item in noteArray, which is 300. The statement inside the loop prints that number on the screen of the micro:bit. Then the loop sets value equal to the next item in noteArray and prints that number. This process continues until value is equal to the last item in the array. After the loop prints the last number, it ends.

CHALLENGE

Modify the loop above to make the Finch play a note for each item in the array. Now you can use an array to store a song for your Finch! 

Note: You can find the value variable on the Variables menu, or you can drag it directly from the for element block into a block inside the loop. 

Click Here to see example code.

You can add measurements from the Finch sensors to an array to store them. To do this, you use the add value block from the Arrays menu.

Create an array named lightArray. Set this array to an empty array. You can do this by using the – button to delete all of the items in the set to block.

Now you can add light measurements to your array. For instance, this loop adds ten light measurements, one per second, to lightArray.

CHALLENGE

Try out the code above, and then add a loop that moves through the array and uses each of the light measurements to set the brightness of the Finch tail lights. For example, if the array contains the numbers 22, 50, etc., then the brightness of the tail lights should be 22 for one second, then 50 for one second, and so on.

Click Here to see example code.

To create a timer in MakeCode, you can use the running time (ms) block. It is on the Input menu, but you need to click more to see it. This block measures the time in milliseconds since the program started.

To make a timer useful in your program, you need to be able to reset it without restarting the program. To do this, we will define some variables that use the running time (ms) block. Declare two variables named startTime and timer.

The variable startTime will hold the time at which you reset your timer. For example, this code sets the value of startTime each time you press button A.

You can then use startTime to create a timer variable that measures how many milliseconds have passed since you last reset the timer. Calculate the value of timer by subtracting startTime from the running time (ms) block. You can perform this calculation in a forever loop so that your timer always has a value when you need one.

CHALLENGE

Create a timer. Write a program that prints the value of your timer to the screen when you press button B. Make sure that you can reset your timer by pressing button A.

Click Here to see example code.

You can use your timer to measure how long it takes for an event to occur. As an example, this program measures the time that it takes the user to place the Finch in the Beak Up position. When button A is pressed, the program resets the timer. Then it waits until the Finch is in the Beak Up position. After the Finch is placed in that position, the program tells the user the value of the timer, which is the amount of time between the button press and the Finch being placed Beak Up.

CHALLENGE

Write a program that makes the Finch move forward until it finds a line. The program should display how long it takes the robot to find the line.

Click Here to see example code.

You can also use the timer to make the robot repeat a set of actions for a certain amount of time. For example, this program will make the Finch blink its beak for 5 seconds. When the value of the timer is more than 5 seconds, the loop stops. There is a short pause after we set the value of startTime. This is to ensure that the forever loop has a chance to update the value of timer before we check it in the while loop.

CHALLENGE

Modify this code to make the Finch blink its beak for 15 seconds or until it sees an obstacle, whichever happens first. Then, have the program use the micro:bit screen to report to the user whether or not the robot has seen an obstacle. If it has seen an obstacle, it should display a smiley face. If it has not, it should display a frowny face.

Click Here to see example code.

You can even combine timers with additional variables. For example, suppose you want the robot to move randomly for 15 seconds, and you want to change the random wheel speeds every second. You can do this with a variable and a timer using the code shown below. The program starts by setting the variable n equal to 1 and resetting the timer. Then a loop repeats until the value of the timer is more than 15 seconds. The action that is repeated inside the loop is to set the speeds of the wheels to random values every second. If the value of the timer is greater than n = 1, it sets the wheel speeds and increases the value of n to 2. If the value of the timer is greater than n = 2, it sets the wheel speeds and increases the value of n to 3. This process continues until the value of the timer is greater than 15 and the loop ends.

Note: This program may not run properly without the pause block in the while loop. For more information on why this is, see this article.

CHALLENGE

Try out the code above and make sure you understand what is happening. Then modify this code so that the Finch moves randomly until either it finds an obstacle or the timer reaches 15 seconds. If the Finch finds an obstacle within the allotted time, it should celebrate by turning its tail green and beeping happily. If it does not find an obstacle within 15 seconds, it should turn its tail red and make a low, mournful beep.

Click Here to see example code.

Custom blocks are also called functions in MakeCode. In computer science, a function is a self-contained piece of code that can be reused by a program. 

You can create your own MakeCode blocks using the Functions menu under Advanced. Click on the Make a Function button.

Name your function “drawSquare” and click Done.

Now you will see a function drawSquare block in your project and a call drawSquare block on the Functions menu. Place the code to draw a square inside the function drawSquare block. Then every time your program uses the call drawSquare block, the Finch will move in a square.

CHALLENGE

Use the call drawSquare block to draw multiple squares. Move or turn the Finch a little bit before drawing each new square. What interesting patterns can you create?

Click Here to see example code.

You can create additional blocks by making more functions!

CHALLENGE

Create a function called “drawCircle.” Then use this function to draw multiple circles. What interesting patterns can you make with both squares and circles?

Click Here to see example code.

You can use parameters to change the behavior of your custom blocks. A parameter is a piece of information that is passed to a function when it is used in a program. For example, you can modify the drawSquare function to use a parameter to determine the side length of the square. 

Right-click on the function drawSquare block and select Edit Function.

In the Edit Function box, click the Number button. Name your parameter sideLength and click Done.

Now your function drawSquare block has a variable named sideLength. Drag this variable from the function drawSquare block into the Finch Move block inside your function.

Now you can use this parameter to change the size of the square that the Finch draws. For example, this loop will draw five squares with random sizes.

CHALLENGE

Create a function to make the Finch move in a polygon. Use a parameter to set the number of sides of the polygon. To draw a polygon, the Finch has to turn a total of 360°, so you can divide 360° by the number of sides to find the number of degrees for each turn. What interesting patterns can you make with your polygons?

Click Here to see example code.