Displaying sensor data on screen in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output on the LCD screen?

Given the Arduino code below, what will be displayed on the LCD screen after running?

Arduino

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
int sensorValue = 512;
void setup() {
  lcd.begin(16, 2);
  lcd.print("Sensor:");
  lcd.setCursor(0, 1);
  lcd.print(sensorValue);
}
void loop() {
  // no changes
}

A

Sensor:
1023

B Sensor: 512

C

Sensor:
512

D Sensor: 1023

💡 Hint

Look at how the cursor is set before printing the sensor value.

The lcd.print("Sensor:") writes on the first line. lcd.setCursor(0, 1) moves to the start of the second line, then lcd.print(sensorValue) prints 512 there.

🧠 Conceptual

intermediate

Why use lcd.setCursor() before printing sensor data?

In Arduino LCD programming, why do we use lcd.setCursor() before printing sensor data?

A To move the cursor to the desired position on the screen before printing

B To clear the screen before printing new data

C To change the font size of the printed text

D To turn off the LCD backlight

💡 Hint

Think about where the text appears on the LCD.

lcd.setCursor(column, row) moves the cursor to a specific position so the next printed text appears there.

❓ Predict Output

advanced

What will the serial monitor show?

Consider this Arduino code snippet reading a sensor and printing to Serial Monitor. What is the output?

Arduino

void setup() {
  Serial.begin(9600);
}
void loop() {
  int sensorValue = analogRead(A0);
  Serial.print("Value: ");
  Serial.println(sensorValue);
  delay(1000);
}

A No output, code has error

B Value: 0 to 1023 (changing every second)

C Value: 1023 only

D Value: 0 only

💡 Hint

analogRead reads values from 0 to 1023 depending on sensor input.

analogRead(A0) returns a value between 0 and 1023 depending on the sensor voltage. The code prints this value every second.

🔧 Debug

advanced

Identify the error in this LCD display code

What error will this Arduino code cause when trying to display sensor data on LCD?

Arduino

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
int sensorValue;
void setup() {
  lcd.begin(16, 2);
  sensorValue = analogRead(A0);
  lcd.print("Value: ");
  lcd.print(sensorValue);
}
void loop() {
  // empty
}

A analogRead(A0) cannot be called in setup() causing runtime error

B lcd.begin() is missing parameters causing compile error

C lcd.print() requires a delay after each call or it crashes

D lcd.print(sensorValue) prints a number but cursor is not moved, so text overlaps

💡 Hint

Think about how lcd.print works when printing multiple things in a row.

lcd.print("Value: ") prints text starting at cursor 0,0. Then lcd.print(sensorValue) continues printing immediately after. This can cause overlapping if not managed carefully.

🚀 Application

expert

How to display sensor data updating every 2 seconds on LCD?

Which code snippet correctly reads a sensor and updates the LCD display every 2 seconds, clearing old data before printing new?

A

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup() {
  lcd.begin(16, 2);
}
void loop() {
  int val = analogRead(A0);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Sensor:");
  lcd.setCursor(0, 1);
  lcd.print(val);
  delay(2000);
}

B

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup() {
  lcd.begin(16, 2);
}
void loop() {
  int val = analogRead(A0);
  lcd.setCursor(0, 0);
  lcd.print("Sensor:");
  lcd.setCursor(0, 1);
  lcd.print(val);
  delay(2000);
}

C

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup() {
  lcd.begin(16, 2);
  lcd.clear();
}
void loop() {
  int val = analogRead(A0);
  lcd.setCursor(0, 0);
  lcd.print("Sensor:");
  lcd.setCursor(0, 1);
  lcd.print(val);
  delay(2000);
}

D

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
void setup() {
  lcd.begin(16, 2);
}
void loop() {
  int val = analogRead(A0);
  lcd.clear();
  lcd.print("Sensor:");
  lcd.setCursor(0, 1);
  lcd.print(val);
  delay(2000);
}

💡 Hint

Clearing the screen before printing new data avoids leftover characters.

Option A clears the LCD each loop, sets cursor positions explicitly, and prints the label and value properly, updating every 2 seconds.