1. CTY SAR FCPS Shawn Lupoli, Elliot Tan
Arduino Knock Lab
CTY SAR FCPS
Shawn Lupoli, Elliot Tan

2. What are we working with?

3. How to detect a physical Knock?
A Piezo element can be used to detect vibration, which is produced by our knock.
Piezo is an electronic device which generates a voltage when it is physically deformed by a vibration, sound wave or mechanical strain
Can also put a voltage across a piezo  piezo will vibrate and create a tone
If the sensors output is stronger than a certain threshold, the Arduino will be knocked

4. Arduino Knock Schematic

5. Goal When we “Knock” the piezo element The LED will flash
“Knock!” will be printed to the Serial Monitor

6. Programming “Knock”

7. Knock: Part 1 Initializing global variables Setup()
The LED will be connected to pin 13
The piezo is connected to analog pin 0 (A0)
Threshold value = 1
A variable to store the sensor reading
A variable to store the last LED status
Setup()
pinMode(pin, mode) configures the pin to behave either as an input or an output
Serial.begin(9600) starts using the Serial Port

8. Knock: Part 2 Loop() Read the sensor using analogRead()
If the sensor reading is greater than the threshold
turn on the light
update the LED pin using digitalWrite()
Send string back to the computer’s Serial Monitor
Add in a delay to avoid overloading the serial port buffer

9. CODE

10. Building the Knock circuit

11. Supplies 1 Arduino Leonardo board 1 breadboard
3 short wires (two black, one red)
1 medium wire (red)
2 long wires (two black)
1 LED
1 resistor (1 MΩ)
1 piezo element
* Notes:
Wires are 22 or 24 AWG, solid
Short wires = 5 cm
Medium wires = 12 cm
Long wires = 16 cm

12. Diagram of Knock Circuit

13. Running and reading output
Run the program as normal, but open the Serial monitoring window for the Analog port.

14. Questions?