Our Ninth Lab: Using a Joystick to Draw Lines on an SSD1306 Digital Display

Parts for this Lab are in Bag 8, with the addition of the Joystick

1. Using the setup from the last lab, we'll use the display from Bag 8. As a reminder:

   • Insert the display into f25, f26, f27, and f28
   • Using one of the jumper wires in Bag 8, insert one end to i25 and the other end into i18
   • Using another jumper wire from Bag 8, insert one end to j26 and the other end into j5
   • Using another jumper wire from Bag 8, insert one end to h27 and the other end into b2
   • Using another jumper wire from Bag 8, insert one end to i28 and the other end into a1

2. Using the wires attached to the joystick, connect them as follows:

   • The wire from GND on the joystick goes to i8
   • The wire from +5V on the joystick goes to i6
   • The wire from VRX on the joystick goes to i9
   • The wire from VRY on the joystick goes to i10
   • The wire from SW on the joystick goes to j20

3. When you are finished, your breadboard should look similar to the image below (Note: your wires may be different colors)

Drawing Lines With a Joystick and the SSD1306 Display

• We already added the SSD1306 library to the Pico.

• We also took some time to look at the methods in the SSD1306 library.

  • Did you notice the line method?
  • The line method is called as follows:

    # Draw a line from X1, Y1 to X2, Y2 with pixels turned on
    display.line(x1, y1, x2, y2, 1)
    

• We learned how to read the Analog to Digital Converter inputs in Lab 5. In this case, we are using two of the ADCs.

• Additionally, we learned to read a button press in Lab 3. We do not need to use the interrupt method (although we could)

Challenge

• Using what you learned in the previous labs, do the following:

  • Give the user instructions on how to operate the joystick to clear the screen
  • Wait for the user to press the joystick
  • Clear the screen
  • Read the voltages from the joystick
  • Convert the voltages to a screen coordinate (X, Y)
  • Draw a line from the starting position to the new position
  • Continue until the user clears the screen
  • Don't forget to comment your code!

• Hint: You will need this formula to scale the voltage to a position

  # Takes an input number value and a range between low-and-high and returns it scaled to the new range
  def scaled(value, istart, istop, ostart, ostop):
      return int(ostart + (ostop - ostart) * ((int(value) - istart) / (istop - istart)))