Many embedded systems are written in C/C++. Since you are building skills in this area, it is important that you are introduced to such an application. We will simulate an Arduino, a simple and popular microcontroller, using this free online editor:

Tinkercad (Links to an external site.)

Our goal is to combine a servo motor, a button, and an LED to create a simple device that could be used for something like an electronic lock!

Setup

• Create an account and sign in
  • Ignore the option to create a student account. Just create a regular one.
• Click on circuits in the navigation bar on the left.
• Click on create new circuit
• From the drop down box on the right, select Arduino
• Scroll down and click the Button configuration. Move your cursor to the work area and click again.
• Click the code button near the top right
  • Observe the code in block format
• Click the drop down box at the top left of the coding window. Select Blocks + Text. Observe the code, written in C++.
• The board has several I/O pins for various purposes: Analog input, digitial input / output, analog output via Pulse Width Modulation (PWM), and power supply pins.
  • HIGH represents an output of 5 volts, LOW represents 0 volts
  • setup is called once when the machine boots up
  • loop is called as fast as the processor can call it, depending on how many instructions there are.
    • The core code looks something like this:
      • while(1) { loop() }
• The Button demo code does the following:
  • Read the state of the button on pin 2
  • If the button is being pressed, light up the LED on pin 13
  • Delay for 10 milliseconds before returning from the loop function
• If you click Start Simulation you can see the on board LED light up when you click on the button.
• Read the Arduino Button Tutorial (Links to an external site.)for more information
• Next, click on the Tinkercad button in the top left corner to go back to the dashboard
• Create another new circuit
• This time select Arduino, then servo
• Read the Arduino Servo Tutorial (Links to an external site.) for more information
  • Note: The servo example uses a loop to sweep angles on the servo. This is not necessary. Regardless of its position, if you call servo_9.write(angle) once, it will move to that angle if it is given enough time. It is not necessary to send the command more than once.
• Repeat the same process for an LED. This time choose Blink (Links to an external site.) from the Arduino drop down menu.

Instructions

• Create a project where you combine a button, a servo, and an LED into one Arduino controller
• Switch your editor to use only C++ text. You may not edit your code using the block editor.
• Combine the code from each project. Some of the demo code may not be needed.
  • You do not need a loop to move your servo, even though the servo demo has one.
• If the user has the button pressed down, move the servo to position 180 and turn the LED on.
• If the button is not being pressed, move the servo to position 0 and turn the LED off.
• Write a delay at the end of your loop function, something like delay(15), so the simulator does not get overwhelmed.
• This system could be used for something like an electronic lock.
• Below is a video showing the end result: