
Rover: Tablet Control
Install BirdBlox onto your tablet or smartphone.
Optional step: If your micro:bit is already flashing 3 or 10 letters when powered on, you can skip this step.
Download this file and drag it onto the micro:bit (you will need a computer with a USB port for this step). Your device should start to flash ten letters on its display. You will only need to complete this step once for each Hummingbird – as long as your device is flashing its initials, you are ready to connect via Bluetooth.
Tap the Hummingbird Connect button. Select Connect Device.
Tap the name of your device. To identify your device, look at the three letters that flash on the micro:bit before the # symbol. Match these to the Bit name(s) on tablet.
When you connect to the Bit, you will hear the connection tone, and the initials will stop flashing. On the tablet screen, the dot on the Hummingbird Connect button will turn green, and the blocks for the Bit will turn teal.
Note: If you lose the connection to the Hummingbird, the initials will start to flash, the dot on the Hummingbird Connect button will turn red, and the blocks for the Bit will turn gray. If this happens, tap the Hummingbird Connect button, select Disconnect Device, and then reconnect.
In addition to the programming tutorials on this page, we have a lot of other resources to help you work with with your Hummingbird Kit.
- Our coding cards provide printable programming help for your students.
- Our blocks document is a handy reference guide that lists all the Hummingbird blocks in BirdBlox.
- Our Build pages offer tutorials and inspiration for building your own robots and mechanisms.
- Our free Professional Development course ties everything together in an online course you can watch at your own pace.
Sharing Files
Introduction
This module will show you how to email a program to and from BirdBlox and provide links to articles that describe cloud-based methods of sharing files.
If you are still learning to program your Hummingbird, skip to the Single Color LED module and come back here when you want to share your program.

There are a number of other sharing options available in BirdBlox! Use these links to learn more.
Single Color LED
This module will show you how to use a single color LED with the Hummingbird Bit. A single color LED is a small light with two wires. The colored wire shows the color of the LED. The Hummingbird kit comes with red, green, and yellow LEDS.
Please note that there is no sound in these videos.
Tri-Color LED
This module will show you how to use a tri-color LED with the Hummingbird Bit. A tri-color LED is a small light with four wires. The tri-color LED actually has three tiny lights inside it. One is red, one is green, and one is blue. You can combine different amounts of red, green, and blue light to make different colors.
Please note that there is no sound in these videos.
Position Servo
In this module, you will learn to use the position servo. The position servo is a motor that moves to a particular angle. The Hummingbird position servo can move to any angle from 0° to 180°.
Hummingbird Base Kit users have an FS90 Micro Servo that works the same as the servo in these modules.
Please note that there is no sound in these videos.
When the green flag is tapped, the Bit Position Servo is set to 90°. Since the servo was not programmed to move to any other position, it does not move again.
Reflect: Why do you think the position servo moves once, then stops at 90°? Would the servo move if it was already at 90° before you start the program?
Rotation Servo
In this module, you will learn to use the rotation servo. The rotation servo is a motor that can rotate at different speeds.
The rotation servo is not included in the Hummingbird Bit Base Kit.
Please note that there is no sound in these videos.
Buzzer
This module will show you how to program the buzzer output on the Hummingbird Bit. The buzzer can be used to create different musical tones that come directly from the Hummingbird controller board. The range of the buzzer is 32 to 135. This range uses the same MIDI note numbers as Scratch and Snap!.
Please note that there is no sound in these videos.
Drag out the Bit Play Note __ for __ Beats block from the Robots folder and attach to a when Green Flag tapped block. Drag out a second Bit Play Note block and change the note. Drag out a third Bit Play Note block and change the note.
The range of the buzzer is 32 to 135. These numbers are MIDI note numbers.
To make the notes play faster or slower, use the set tempo to __ bpm block, located in the Sound folder. Snap the set tempo to __ bpm block into the top of your script.
The “tempo” is the speed of a song. It is measured in beats per minute (bpm). BirdBlox defaults to 60 bpm. Change the tempo by clicking the white oval and typing in a new tempo.
Using a bit of math, we can figure out that a song with 120 bpm has beats that last half a second (120 bpm / 60 seconds in a minute = 2 beats in each second). Click the white oval to change the bpm and see how that affects the speed of the notes.
Reflect: What would you set the bpm to make a song where each beat = 1 second?
Playing Sounds
The Sound menu in BirdBlox contains blocks that can be used to play sounds through the tablet speakers.

The play sound and play sound until done blocks can be used to play one of a number of precorded sounds. You can select a sound from the drop-down menu. The play sound block will start the sound and then move immediately to the next line in the program. For example, when you run this program, the light comes on as soon as you start the sound.

The play sound until done block will pause the program until the sound is complete. That means that when you run this program, the light will not come on until the sound has finished.

CHALLENGE
Use a servo and the sound blocks to make an alarm. Set the servo to one position and make a ticking sound. After the ticking, move the servo to a different position and sound the alarm!
Click Here to see example code.
Recording Sounds
You can also record your own sounds in BirdBlox. Tap Record Sound on the Sound menu. Then press the Record button and give BirdBlox permission to use the microphone.

You can record up to five minutes of sound. Tap the Stop button when you are done.

Your recording will appear. You can play it back or rename it from this screen. Then tap Done.

CHALLENGE
Record a portion of a favorite song in BirdBlox.
Playing Recordings
Once you have recorded a sound, you can play it using the play recording or play recording until done blocks from the Sound menu.
The play recording block will start the sound and then move immediately to the next line in the program, while the play recording until done block will pause the program until the sound is complete.
For example, this program will play the recording while the servo moves back and forth.

If you need to, you can use the stop all sounds block to stop a sound or a recording in the middle.

Light Sensor
This module will show you how to use a light sensor as an input with the Hummingbird Bit. A light sensor is a component that collects data based on how much light surrounds the sensor. The range of the light sensor is 0 to 100.
This module assumes that you have already completed the single color LED module.
Please note that there is no sound in these videos.
Dial Sensor
This module will show you how to use a dial sensor as an input with the Hummingbird Bit. A dial sensor is a component that collects data based on how much you rotate the knob. The range of the dial sensor is 0 to 100.
This module assumes that you have already completed the single color LED module.
Please note that there is no sound in these videos.
Distance Sensor
This module will show you how to use a distance sensor as an input with the Hummingbird Bit. A distance sensor is a component that collects data based on how close or far you are to the sensor. The range of the distance sensor is 1 to 260 cm.
The distance sensor is not included in the Hummingbird Bit Base Kit.
This module assumes that you have already completed the single color LED module.
Please note that there is no sound in these videos.
This program compares the value of the distance sensor to 15. If the sensor value is less than 15, the program runs the block inside the if section of the if else, and the LED turns on. When the sensor value is greater than 15, the program runs the block inside the else section, turning the LED off.
Sound Sensor
This module will show you how to use a sound sensor as an input with the Hummingbird Bit. A sound sensor is a component that collects data based on how much sound surrounds the sensor. The range of the sound sensor is 0 to 100.
The sound sensor is not included in the Hummingbird Bit Base Kit.
This module assumes that you have already completed the single color LED module.
Please note that there is no sound in these videos.
Buttons
This module will show you how to program the A and B buttons on the micro:bit to control the single color LED output of the Hummingbird Bit. The micro:bit’s A and B buttons can be used as inputs. Pressing them can be an “event” to trigger other actions.
This module assumes that you have already completed the single color LED module.
Please note that there is no sound in these videos.
From the Control folder, drag out a when green flag tapped block, and attach a repeat forever loop. Drag an if statement into the forever loop. From the Robots folder, drag out a Bit button A block and place it in the hexagon of the if statement. Drag a Bit LED block into the if statement and set it to 100%.
Accelerometer
This module will show you how to use the accelerometer as an input to control the tri-color LED from the Hummingbird. The range of the x, y, and z variables on the accelerometer is -10 to +10 m/s^2.
This module assumes that you have already completed the tri-color LED module.
Please note that there is no sound in these videos.
From the Control folder, drag out a when green flag tapped block, repeat forever loop, and if statement block, and connect them with the if statement inside the repeat forever loop.
Nest a Bit Screen Up block from the Robots folder into the hexagon space of the if statement. Use the drop down menu to select “Shake.”
Drag out 2 Bit Tri-LED blocks from the Robots folder, and 1 wait block from the Control folder. Write a program to turn the tri-color LED red, wait 1 second, and turn off when the micro:bit is shaken.
You can also tilt your Hummingbird Bit in different directions to change colors of the tri-color LED.
First, delete the wait and second Bit Tri-LED blocks. Select the drop down menu in the Bit Shake block, and change it to read “Bit Logo Up.” Duplicate the if statement. Then, click the second drop down menu to select “Bit Logo Down.” Change the second Bit Tri-LED to 100% green.
While we’ve been using the accelerometer as an event up to this point, you can also use the accelerometer’s value to slowly alter a component by nesting it, which you can also do with sensors.
First, save 1 Bit Tri-LED block, but delete everything else inside the repeat forever loop. Nest a Bit Accelerometer block inside the Bit Tri-LED “R” oval. The range of the accelerometer is -10 to +10 m/s^2.
Write a program that:
– Makes the x variable of the accelerometer control the brightness of the red of the tri-color LED.
– Makes the y variable of the accelerometer control the brightness of the blue of the tri-color LED.
– Makes the z variable of the accelerometer control the brightness of the green of the tri-color LED.
First, we must calibrate the compass. To do this, click the settings icon in the top left corner and click “Calibrate Compass.” Select your Hummingbird. When prompted, tilt your Hummingbird every direction in the air. If successfully calibrated, a check mark will appear on both the LED screen and next to your Hummingbird’s name. If unsuccessful, try again.
The compass value can also be used to make decisions. We will now set your position servo to either 0 or 180 degrees based on the compass value.
First, drag the Bit Compass and Bit Position Servo blocks apart and outside of the repeat forever loop. Drag an if else block from the Control folder into the repeat forever loop. Nest a less than block from the Operators folder into the hexagon space of the if else block. Nest the Bit Compass block into the first space of the less than block. Set the threshold to 180 degrees.
Drag the Bit Position Servo block into the first open space of the if else block and set it to “0.” Drag another Bit Position Servo block into the second open space of the if else block and set it to “180.”
This program compares the value of the compass to 180. If the compass value is less than 180 (indicating west), the program runs the block inside the position servo is set to 0 degrees. When the compass value is greater than 180 (indicating east), the position servo is set to 180 degrees.
Reflect: How could you use a similar code to turn a tri-color LED red and blue based on the value of the compass?
Multiple Devices
This module will show you how to connect multiple devices through the BirdBlox App. It will also show you how to control the outputs of one Hummingbird with the inputs of another, wirelessly. For this module, you will need 2 Hummingbird Bit boards*, 1 tri-color LED, and 1 dial sensor.
This module assumes that you have already completed the tri-color LED, buttons, and sensor modules.
*In steps 2-7, you will be using a micro:bit by itself without a Hummingbird controller board. To power this micro:bit, you can either use a AAA battery pack or the USB cord included in your kit.
Please note that there is no sound in these videos.
Plug in the tri-color LED into port 1. You will also need a separate micro:bit unplugged from a Hummingbird, which you can power by a USB cable or AAA battery pack (not included). We will be using a battery pack.
We will begin by connecting 2 devices to the BirdBlox App. We will first be connecting a Hummingbird Bit and also a micro:bit by itself.
First, select the Hummingbird Connect button in the top left of the BirdBlox screen. Select “Connect Multiple.” Select the + icon to connect devices. Connect the Hummingbird first. Then connect the micro:bit. Select “Done.”
We will now program the sending and receiving components of the robots. We will write a program that changes the color of a tri-color LED using the micro:bit’s A and B buttons.
From the Control folder, drag out a when green flag tapped block, repeat forever loop, and if statement block, and connect them with the if statement inside the repeat forever loop.
Go to the Robots folder, and minimize the Hummingbird Bit blocks by touching the small arrow. Maximize the micro:bit blocks by touching the small arrow. Nest a micro:bit Button A block into the hexagon space of the if statement block.
Minimize the micro:bit blocks and maximize the Hummingbird Bit blocks. Drag our a Bit Tri-LED block into the open space of the if statement. Change the Bit Tri-LED to 100% red.
Now we want to program our robots so that pressing the A and B buttons on the micro:bit will turn the Hummingbird tri-color LED red and blue.
First, duplicate the if statement containing micro:bit button A and place it below the first if statement within the repeat forever loop. Change it to micro:bit button B, and change second Bit Tri-LED to 100% blue.
When the A button is pressed on the micro:bit, the Hummingbird tri-color LED turns red. When the B button is pressed on the micro:bit, the Hummingbird tri-color LED turns blue.
Reflect: Could you do something similar with a position servo, setting it to either 0 or 180 degrees based on which button is pressed?
Disconnect the micro:bit from the BirdBlox App by clicking the Hummingbird Connect button in the top left and pressing the X next to your micro:bit. The micro:bit will resume flashing 3 letters. Plug this micro:bit into a Hummingbird controller board. Then plug a dial sensor into Sensor port 1. Connect the second Hummingbird using the Hummingbird Connect button.
We will call the first the Hummingbird you were using HB1. The Hummingbird you just connected will be HB2.
Now we’re going to program a dial sensor on HB2 to control the tri-color LED on HB1.
First, delete everything but the when green flag tapped and repeat forever blocks. From the Control folder, drag an if else statement into the repeat forever loop. From the Operators folder, nest a less than block into the hexagon shape of the if else statement. From the Robots folder, nest a Bit Light sensor block into the first open space in the less than block. Use the first drop down menu to select “Bit 2” (meaning HB2), and use the second drop down menu to select “Dial.” Set the threshold to 50.
Drag a Bit Tri-LED block into the first open space and set it to 100% red. Drag another Bit Tri-LED block into the “else” space and set it to 100% blue. Leave both Bit Tri-LED blocks set to Bit 1.
Now we will use the dial on HB2 to control the brightness of the tri-color LED on HB1 in real time.
Save the Bit 2 Dial block and the Bit 1 Tri-LED block. Delete everything else inside the forever loop. Drag the Bit 1 Tri-LED block into the forever loop. Nest the Bit 2 Dial block into the “R” space on the Bit 1 Tri-LED block.
The Touch Sensor
The gold micro:bit logo is a button that returns true if you are touching it and false if you are not. This sensor is a third drop-down option in the Bit Button block.
For example, you can make a tri-LED turn green when you are touching the button and red otherwise.

CHALLENGE
Write a program that moves the position servo to 0° when you press button A, 90° when you press button B, and 180° when you touch the logo.
Click Here to see example code.
The Sound Sensor
The micro:bit sound sensor can detect a noise like a clap. This is similar to the sound sensor that comes with the Hummingbird Premium kit, but it is contained in the micro:bit rather than a separate sensor. The range of the sound sensor is 0-100.
The sound sensor is the default option in the Bit Sound/Temperature block. For example, you can make the rotation servo stop when the Hummingbird detects a noise.

The Bit Sound/Temperature block will be gray if you do not have a micro:bit V2. This means you cannot use it.
CHALLENGE
Make the Hummingbird play a note when you clap your hands.
Click Here to see example code.
The Temperature Sensor
The micro:bit temperature sensor returns the temperature in degrees Celsius. This sensor is a drop-down option in the Bit Sound/Temperature block. For example, you can display an “H” on the micro:bit when the temperature is warmer than 20 degrees, and a “C” otherwise.

CHALLENGE
Make a tri-color LED turn blue when the Hummingbird detects that it is cold and red otherwise.
Click Here to see example code.
Variables
What is a variable? In programming, a variable is a value that can change, depending on conditions or on information passed to the program. Using variables with the Hummingbird Robotics Kit will help you create robots with more advanced functions.
Before you begin this module, make sure that you have completed the single color LED module, the position servo module, the buttons module, and at least one of the sensor modules.
Nesting a variable into an output block is one way to use a variable. You can also use a variable to control robot expressions. If the variable equals 1, your robot can perform one set of actions. If you variable equals 2, your robot can perform a different set of actions.
Try building a robot using the variable to control different expressions. You can build any type of robot you want, but we recommend building the Tiny Drummer.
Programming a position servo to move slowly is very similar to programming an LED to fade in and out. Nest the counting variable block inside of a position servo block instead of an LED block.
To manually control the speed of that position servo with the A and B buttons we will need a new variable. Create a second variable and call it “time.”
If the wait time between servo positions is too big or too small, the servo can become difficult to work with. Set some parameters for your time variable. There are many ways to set variable parameters.
Try to build a robot that uses 2 slow moving servos. You can build anything you want, but we recommend the Little Bot.
Rover: Driving and Avoiding Obstacles
In this module, you will program a mobile robot to move and avoid obstacles. You will need a rover for this module, so go ahead and build one with this tutorial. We kept our rover pretty simple, but feel free to make yours a parade float, a bananamobile, or whatever you can dream up!
Note: The rover modules assume that you have already completed the modules in the Inputs and Outputs sections.
Moving Forward and Back
The two rotation servos on the rover point in opposite directions.
This means that to move the rover forward, the two servos must move in opposite directions.

To move the rover forward, set the speed of rotation servo 1 to 100% and the speed of rotation servo 2 to -100%.

CHALLENGE
Try out this code. Experiment with different wheel speeds to see how you can move the rover in different ways. How can you move backward?
Click Here to see example code.
Turning
When the speeds of the rotation servos are equal, the robot turns in place.
Notice that this code turns the rotation servos off at the end of the program. Otherwise, they will remain on when the script ends, and the rover will keep spinning.

CHALLENGE
Try out this code. How can you change how far the robot turns?
Click Here to see example code.
Avoiding Obstacles
You can use the distance sensor to help your robot avoid obstacles. This program will stop the rover when it sees an obstacle less than 20 cm away. Otherwise, the rover will move forward.

CHALLENGE
Modify your program to make the rover back up and turn left when it sees an obstacle. Now your rover can wander around the room!
Click Here to see example code.
Adding Extras
The rover also has two tri-color LEDs for headlights and a servo that controls the steering wheel. You can incorporate these components into your program as well.
CHALLENGE
Make the headlights turn red when the rover is moving away from an obstacle and green when the rover is moving forward. Make your driver steer by turning the steering wheel to the left as the robot turns left and back to the center when it is moving forward or back.
Click Here to see example code.
Generating Random Numbers
The pick random block is on the Operators menu in BirdBlox. This block randomly chooses a number between the two limits given. For example, this block generates a number between 1 and 100. Each time you tap 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 rover wheel to a random number every two seconds. This program will make your rover wander randomly about the room!
Notice that each wheel gets a different random number, so the Finch will mostly turn but sometimes move straight. The random number for rotation servo 2 is multiplied by -1 to make this number negative.

CHALLENGE
Use the pick random block to set the rover headlights to different random colors as the Finch moves randomly around the room.
Click Here to see example code.
Randomness with Variables
If you want to set both headlights to the same random color, you can add a variable to your program. Create a variable called red. If you need more information about how to make and use a variable, refer to the Variables module.
Set your variable equal to a random number between 0 and 100. Then set the amount of red for the tri-color LEDs to red.

CHALLENGE
Create two variables, green and blue. Set each of these variables to a random number, and then use these variables to set the amount of green and blue light for both tri-color LEDs. When you are done, your program should set both tri-color LEDs to the same random color every second.
Click Here to see example code.
The Tablet Orientation Block
The Tablet Orientation block on the Tablet menu is a Boolean block that tells you whether or not the tablet is in a particular position. For example, this code will move the rover forward when the tablet is positioned so that the camera is down. When the tablet is positioned with the screen up (flat on the tablet) the rover will stop.

CHALLENGE
Write scripts to make the rover move and turn based on the orientation of the tablet. The robot should move both forward and back and turn in both directions. The robot should stop when the tablet is positioned with the screen up.
Click Here to see example code.
The Tablet Accelerometer Block
To get finer control of the rover’s speed, you can use the Tablet Accelerometer block to directly control the rotation servos.
The tablet accelerometer measures any force that causes acceleration in the x-, y-, or z-direction. Because the tablet is usually moving pretty slowly, the accelerometer mostly measures the acceleration due to gravity. When the tablet is sitting on a level surface, the acceleration due to gravity points through the base of the tablet, along the negative z-axis. If you instead position the tablet so that its camera is at the bottom, the acceleration due to gravity points along the positive y -axis. The Tablet Accelerometer block enables you to measure these differences.

To use the Tablet Accelerometer block, select the axis (X, Y, or Z) in the block. The block will report the acceleration in that direction in meters per second squared. Each acceleration value is roughly between -10 and 10. As an example, this code uses the x-axis of the accelerometer to control the speed of rotation servo 1. Notice that the accelerometer value is multiplied by 10 to get a value between -100 and 100, the limits of the rotation servo speed.

CHALLENGE
Write a program that moves the rover forward or backward using the x-axis of the accelerometer.
Click Here to see example code.
Using Two Accelerometer Axes
Now that you are using the x-axis of the accelerometer to move forward and back, it would be nice to use the y-axis to turn the rover. However, first you have to decide if the robot should be turning. You can do this based on which acceleration value is larger. If the absolute value of the x-acceleration is larger than the absolute value of the y-acceleration, then the robot should move in a straight line. Otherwise, the robot should turn.

CHALLENGE
Use the sample code above to write a program that moves the robot forward or backward using the x-axis of the accelerometer when the x-acceleration value is larger than the y-acceleration. Otherwise, the robot should turn left or right using the y-axis of the accelerometer.
Click Here to see example code.
Calibrating the Compass
Before you use the compass, you need to calibrate it in BirdBlox. To do this, tap the Calibrate Compass button on the Settings menu.

Tap the name of the Hummingbird Bit, and then follow along with the video to move your Bit around in different directions to calibrate it. You should see a green check by the Bit name when you have successfully calibrated. If you see a red X, try again.

The Bit Compass Block
Once you have successfully calibrated, you can use the Bit Compass block on the Robots menu to read the value of the compass.

The compass value will be between 0° and 359°. 0° corresponds to the direction of magnetic north. The angle increases as the robot turns clockwise, so 90° is east, 180° is south, and 270° is west.
To use the compass, the micro:bit must be positioned so that the LED display is parallel to the ground. Otherwise, the compass will not provide useful measurements.

CHALLENGE
Write a program that continually displays the value of the compass at the bottom of the tablet screen. Watch this value change as you slowly turn the rover.
Click Here to see example code.
Displaying Direction
You can use the compass to make the rover tell you the direction it is heading in.
For example, if the value of the compass is between 45 and 135, use the Display block to print “East” on the tablet screen.
You can use the and block on the Operators menu to combine comparisons. The and block will be true only when both Boolean blocks inside it are true.

CHALLENGE
Add a second if else block to your script as shown. Modify the nested if else to show “South” when the value of the compass is between 135 and 225.
Click Here to see example code.

Driving with the Compass
You can also use the compass to make the rover move in a particular direction. For example, this code makes the robot turn clockwise when the compass is less than 180° and counterclockwise otherwise. Try placing the rover in different positions before running this script. Which direction does the rover drive in?

CHALLENGE
Modify your program so that the robot drives south as long as there is no obstacle in the way. When the robot encounters an obstacle, it should back up and turn.
Click Here to see example code.
Making a Line Tracking Sensor
You will use a single color LED and a light sensor to create a line tracking sensor. To track a black line on a light-colored surface, you need to know whether the sensor is over a black surface or a white surface. You can determine this by measuring the amount of light reflected by the surface. A white (or light-colored) surface reflects a lot of light, while a black surface reflects very little light.

In addition to a single color LED and a light sensor, you will need a piece of cardboard that is roughly 8 cm by 15 cm and a metal brad.

Poke holes in the cardboard so that you can mount the LED and the light sensor close together along one of the long edges of the cardboard. Use the metal brad to hold the light sensor in place.

Glue the piece of cardboard to the bottom of the rover’s rotation servos, the LED and the light sensor should be pointing at the ground and 1-2 cm away from the ground.
Connect the single color LED to LED port 1 and the light sensor to sensor port 2.

Basic Line Tracking
To track a line, the rover 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 as the rover moves clockwise around the loop. When the line sensor is over the black line, the rover should turn left. When the line sensor is over the white line, the rover should turn right.
Notice that this sample code uses the rotation servos to turn using only one wheel at a time. This means that both turns move the robot slightly forward. As the program repeats the if else block over and over, the rover will follow the line as it turns back and forth.
Note 1: As you run a BirdBlox program, the app relays commands over Bluetooth to the robot. There is some delay in this process, and that means that you need to turn slowly to track the line.
Note 2: Rotation servos can vary a lot, so what is a slow speed for one motor may not be for another motor. For example, in the sample code one motor is running at 20% while the other runs at -50%.

CHALLENGE
Try out this code. You may need to adjust the line sensor threshold and the turning speed of each rotation servo in order to track your line. The Display block will show you the light sensor value so that you can choose a good threshold.
More Line Tracking
You can combine line tracking with other robot behaviors to make more complex programs! For example, the robot can track the line only until it finds an obstacle or hears a loud noise.
CHALLENGE
Write a program that makes the rover track a line but stops the rover when there is an obstacle in front of it.
Click Here to see example code.
Flower: Sensor Control
In this module, you will write BirdBlox programs to control a robotic flower. You will need a flower for this module, so use these instructions to build one if you haven’t already.
You should also connect a dial sensor to sensor port 1 for this module.
Note: The flower modules assume that you have already completed the modules in the Inputs and Outputs sections.
The Dial Sensor
You will start by using the Bit dial sensor to control the LEDs.
A convenient way to see the value of the sensor is to use the Display block on the Tablet menu. Use a forever loop to continually display the value of the sensor on the screen.

CHALLENGE
Use the dial to control the brightness of the single color LEDs.
Click Here to see example code.
Math Blocks with the Dial
You can also use the math blocks on the Operators menu to change the behavior of your program. For example, this program will also make tri-color LED 1 gradually change from blue to red as you turn the dial from 0 to 100.

CHALLENGE
Modify your project as follows:
- LED 2 should go from fully on to fully off as you turn the dial from 0 to 100.
- Tri-color LED 2 should change from red to blue as you turn the dial from 0 to 100.
Click Here to see example code.
The Accelerometer
You can also use the accelerometer to control how much the flower blooms.
The micro:bit accelerometer measures how much the micro:bit is tilting in three different directions, which are called x, y, and z. The value of the acceleration is between -10 m/s2 and 10 m/s2 for each direction.

You can measure the acceleration in the x, y, and z directions using the Bit Accelerometer block on the Robots menu.

CHALLENGE
Write a program to see the x-value of the accelerometer change as you tilt the Hummingbird in different directions. For an extra challenge, display the y– and z-values of the accelerometer as well.
Click Here to see example code.
Math Blocks with the Accelerometer
The x-value of the acceleration is between -10 and 10. To make the flower bloom, we want to use this value to calculate an angle for the position servo.
For example, if we calculate the angle by multiplying the x-acceleration by 4 then as the x-value of the acceleration changes from 0 to 10, the angle will change from 0° to 40°.

CHALLENGE
Adjust the program so that the flower fully blooms as you tilt the Hummingbird Bit to the left (so that the sensor ports are toward the table and the LED ports point toward the ceiling).
Click Here to see example code.
CHALLENGE
The flower doesn’t bloom when you tilt the Bit to the right because the micro:bit x-acceleration is less than 0. How can you make your flower bloom when you tilt the Bit to the right or left?
Hint: You can do this using an if else block or a block from the Operators menu.
Click Here to see example code.
The repeat Block
You have been using forever loops to repeat blocks. You can also use the repeat block on the Control menu.
This block repeats whatever is inside it a certain number of times.
For example, this code will make an LED turn on and off 10 times.

CHALLENGE
Write a program to make the flower open and close 5 times.
Click Here to see example code.
Loops with Variables
To make the flower bloom gradually, you will use the repeat block with a variable. A variable is a name that represents a value. You can use it to store information.
Go to the Variables menu and click Create Variable. Name your variable count.

You will notice that the Variables menu looks different now. It contains a block for your variable and blocks to change its value.

CHALLENGE
Try out this code and watch the value of count. What does the change by block do? How does the value of count at the end of the script depend on the number in the repeat block?

Loops with Variables
Make your flower bloom gradually using the repeat block and count. Set the number in the repeat block to be the “full bloom” angle for your flower (yours may be different than 90°). Each time through the loop, set the position servo to count and stop briefly. You can vary the length of the wait to make your flower bloom more slowly.

To make the flower bloom repeatedly, place the code inside a forever loop.

CHALLENGE
With one repeat block, the flower blooms gradually and then closes quickly. To make the flower close gradually as well, add a second repeat block. Make the angle of the servo go from 90° to 0° by changing count by -1.
Click Here to see example code.
Adding Loops
You can also use a variable to change the color of the tri-color LEDs.
Add a second variable and a second forever loop with a repeat inside. To make the LED change from green to red, use a subtraction block to make green decrease from 100 to 0 as red increases from 0 to 100.

CHALLENGE
Add two more repeat blocks to your tri-color LED script. Make the LED change from green to red, then red to blue, then blue back to green. Make the program repeat this sequence until you press the stop button.
Click Here to see example code.
CHALLENGE
Add tri-color LED 2 and the single color LEDs to your code. Make tri-color LED 2 gradually change color in a different sequence from tri-color LED 1.
Click Here to see example code.