Laser Head Sensor with micro:bit
A laser head sensor module is one of many useful external components that you can connect to your micro:bit!
In this guide, you will learn to connect the micro:bit with a laser head sensor module and create your own tripwire alarm system. With the addition of a light dependent resistor, the alarm will start to sound when the laser is broken.
By finishing this guide, you will have created a simple tripwire alarm system.
|Parts Used in This Guide|
Step 1 The Module
Let's take a closer look at the laser head sensor module.
It has three pins:
- GND: Though it is labelled '-' on the module, this is the the 'GND' pin. In electronics, we define a point in a circuit to be a kind of zero volts or 0V reference point, on which to base all other voltage measurements. This point is called ground or GND.
- Note: Voltage is the difference in electric potential between two points. As it is difficult to talk about voltage without a reference point, we need another point to compare it to.
- Middle Pin: No connection required here
- Signal: This pin is the signal pin, which is the input to control the module
Step 2 Connect module to breadboard
Step 3 Connect P2 to S
Step 4 Connect GND to -
Step 5 Connect + to VCC (Buzzer module)
Step 6 Connect GND to GND (Light-dependent resistor module)
Step 7 Connect P1 to AO
Step 8 Connect + to VCC
Step 9 Connect P0 to I/O
Step 10 Connect GND to GND (Buzzer module)
Step 11 Connect + to 3.3V
Step 12 Code for button A and B!
Now that we have connected the laser head module to the micro:bit, we will program it! We will use the two push buttons on the micro-bit to turn the laser on and off.
- Open up MakeCode editor
- Click on the 'Projects' button then click on 'New Project ...'
- From the 'Input' tab, grab two 'on button A pressed' blocks.
- Then click on the 'Pins' tab to grab two 'digital write pin' blocks.
- Arrange them so that:
- When button A is pressed, pin 2 is set to a value of 0.
- When button B is pressed, pin 2 is set to a value of 1.
Upload this code to the micro:bit and press button A and B to see what it does!
Note: These are the two buttons found on the micro:bit.
Step 13 Add the code for the buzzer!
We have also added a light dependent resistor module and a buzzer module to the circuit. Let's use them!
- Pin 2 has been used to connect to signal (S) of the laser head module, while pin 0 is connected to input or output signal (I/O) of the buzzer module.
- If sensorVal is more than 600, the micro:bit will display the value and then sound the alarm by playing a Middle C tone for 2 beats each time.
- Else, the micro:bit will display the sensorVal when the laser is not broken.
Step 14 Add Some Visuals!
Let's change the code some more to add more visuals. The changes made:
- When the trip wire alarm system goes off now, it will display an angry face using the micro:bit's LEDs.
- Otherwise, if all is well, it will display a smiley face on the LEDs.
Step 15 Send a message to a second micro:bit!
If you have another micro:bit laying around, use the following MakeCode, else skip to the next step!
- We will use another micro:bit to receive a message when the trip wire alarm system goes off.
- Now when the laser is broken and the sensorVal goes above 600, the second micro:bit will display the string, "Intruder alert!".
- This is done using "radio send string" and "on radio received". The two micro:bits can communicate with one another via radio.
Step 16 Upload the code to micro:bit
It's time to upload the code to the micro:bit!
- Connect the micro:bit to your computer by using a microUSB cable
- In MakeCode editor, click on the Download button
- Find the hex file in your Downloads folder or where you have saved it to
- Open up Finder on the MacOS or Explorer on Windows, and drag the hex file into MICROBIT under 'Devices' on the macOS.
- The micro:bit will flash for a few seconds and the trip wire alarm will be all set!