Using two or more input and output components is a must in this assignment. Based on that, I added one input component which is a pushbutton besides the ultrasonic sensor I used the last week. While the additional output component is LCD screen.

1- The -ve terminal of the buzzer is connected to -ve side of the breadboard using a male-male jumper wire, while the +ve terminal is connected to digital pin 2.

2- The GND pin of the ultrasonic is connected to -ve terminal of the breadboard by using a female-male jumper wire, then a male-male wire is connected from -ve column of the breadboard to GND of Arduino. While the power pin is connected to+ve terminal of breadboard using a female-male jumper wire.

3- The trigger pin of ultrasonic is connected to pin 5 while echo is connected to 6 pin by using two female-male jumper wires.

4- LCD Wiring:

• The Vcc pin is connected using male-female jumper wire with +ve terminal of breadboard.

• GND pin is connected to -ve terminal of breadboard using a male-female jumper.

• SDA & SCL pins are connected to A4 & A5 of Arduino using male-female jumper wires.

5- A terminal of pushbutton is connected to +ve of breadboard while the other terminal is connected to GND which is also connected to pin 3 of Arduino.

6- The +ve and -ve columns of breadboard are connected using male-male jumper wires to 5V pin and GND pin of Arduino respectively.

Here is the most exhausting part! Writing the code using Arduino C.

• First, I downloaded the "Wire" library and "LiquidCrystal_I2C" library.

• Second, I identify several variables which are echo and trigger pins of the ultrasonic sensor using the "long" tool. Then I clarify the pins that trigger and echo are attached to within Arduino using the "pinMode()" tool. Then, I Set the trigger pin to "HIGH" state for 10 microseconds using "delaymicroseconds". Then the echo pin reads and returns the sound wave travel time in microseconds.

• I set the LCD address to 0x27 for a 16 chars and 2 line display.

• Inside "void setup", I identified the pins of buzzer, and pushbutton using "pinMode()". The I initialized the LCD using "lcd.init()" and turned on the backlight using "lcd.backlight()".

• Inside "void loop", I set an if condition. If ultrasonic read a distance more than 7 the buzzer will turn on and the LCD will display "REFILL!" word and inside this if condition I set another if condition which says if the pushbutton read low then clear or reset the LCD screen. If the ultrasonic didn't feel more than 7cm distance (else), the buzzer will stay off (LOW).