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Quizzes > Electronics & Gadgets

Arduino Uno quiz: test your code, pinout, and circuit basics

Quick, free Arduino programming quiz with instant results.

Editorial: Review CompletedCreated By: Bas MeybergUpdated Aug 27, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration for Arduino code quiz with coding and circuit themes on a coral background

This Arduino Uno quiz helps you check your programming, pinout, and circuit basics, then spot gaps before your next build. For more practice, try our digital electronics quiz, microcontroller basics quiz, and electronics quiz.

What type of board is the Arduino UNO?
Microcontroller board
Sensor module
Integrated development environment
Programming language
The Arduino UNO is a popular microcontroller development board based on the ATmega328P chip. It provides digital and analog I/O for building electronic projects. It is not a sensor module or an IDE, although it is programmed via the Arduino IDE. For more information see .
Which programming language is primarily used to write Arduino sketches?
Python
Ruby
C/C++
Java
Arduino sketches are written in C/C++, making use of simplified functions and abstractions provided by the Arduino core. Although the IDE hides some C++ complexity, the underlying language remains C/C++. See .
What is the most common default baud rate used with Serial.begin() in Arduino examples?
115200
4800
9600
19200
Many Arduino examples and tutorials use a baud rate of 9600 bits per second in Serial.begin() as a default for reliable serial communication. This rate balances speed with compatibility for USB-to-serial converters. You can verify this in the official reference at .
Which function is used to configure a digital pin as input or output?
digitalRead
digitalWrite
analogWrite
pinMode
The pinMode() function sets a specified digital pin as either an INPUT or OUTPUT. It must be called in the setup() section before performing reads or writes on that pin. More details are available at .
What voltage level does digitalWrite(pin, HIGH) output on a typical Arduino UNO pin?
5V
12V
0V
3.3V
On the Arduino UNO, writing HIGH to a digital pin sets it to approximately 5V, since the board operates at 5V logic. It is not 3.3V unless you are using a 3.3V board variant. See for more information.
How many digital I/O pins does the Arduino UNO have?
8
14
16
12
The Arduino UNO has 14 digital I/O pins (numbered 0 - 13) that can be used as inputs or outputs. Some of these pins also provide PWM or other specialized functions. You can find the full pinout at .
How many PWM pins are available on the Arduino UNO?
8
10
6
4
The Arduino UNO provides 6 pins capable of PWM output (marked with a '~'): pins 3, 5, 6, 9, 10, and 11. PWM allows analog-like output using digital pulses. Learn more at .
What is the flash memory capacity of the ATmega328P on the Arduino UNO?
128KB
64KB
32KB
16KB
The ATmega328P microcontroller on the Arduino UNO has 32KB of flash memory for storing your sketch code, of which 0.5KB is used by the bootloader. This is detailed in the official board specs: .
Which syntax is used to write a block comment in an Arduino sketch?
/* comment */
# comment
// comment
Block comments in C/C++ (and thus Arduino sketches) are enclosed between /* and */. Line comments use //. HTML comment syntax and # are not valid in Arduino code. See .
Which function reads the value from an analog sensor connected to an analog pin?
analogWrite
digitalRead
sensorRead
analogRead
The analogRead() function reads the voltage on an analog pin and returns a value between 0 and 1023 on a 10-bit ADC. digitalRead() is for digital pins, and analogWrite() outputs PWM signals. Detailed usage is at .
Which library must you include to use the I2C communication interface on Arduino?
I2C communication on Arduino uses the Two-Wire Interface (TWI) library, which is included via . SPI and Serial are different interfaces. Documentation is available at .
What does the function millis() return?
Number of milliseconds since reset
Analog reference voltage
Number of microseconds since reset
CPU clock cycles
millis() returns the number of milliseconds that have passed since the Arduino board began running the current program. It rolls over approximately every 50 days. See for details.
What is the recommended input voltage range when powering the Arduino UNO via the VIN pin or DC barrel jack?
5V to 7V
7V to 12V
3.3V to 5V
12V to 20V
The onboard voltage regulator on the UNO accepts between 7V and 12V at the VIN pin or barrel jack. Lower voltages may cause instability, and higher voltages can overheat the regulator. More info at .
Which technique can help to prevent mechanical switch bouncing in a digital input?
Using a higher supply voltage
Using a hardware pull-down only
Adding a software debounce delay
Increasing the sampling frequency
Mechanical switches often generate multiple transitions (bounce) when toggled. Introducing a debounce delay in software (e.g., delay(50)) or using a debounce algorithm filters out these spurious readings. See .
What is the purpose of a pull-up resistor when used with a digital input pin?
To hold the pin at a defined HIGH level when unconnected
To measure analog voltage levels
To pull the pin to ground when unconnected
To increase the current drive capability
A pull-up resistor ties the input pin to a HIGH state when no external device is driving it, preventing it from floating. The Arduino also offers internal pull-ups via pinMode(pin, INPUT_PULLUP). More at .
What is the resolution (in bits) of the ADC on the Arduino UNO?
10-bit
8-bit
16-bit
12-bit
The Arduino UNO uses a 10-bit analog-to-digital converter, so analogRead() returns values from 0 to 1023. This gives 1024 discrete levels over the reference voltage range. See .
Which function is used to attach an external interrupt to pin 2 on Arduino UNO?
attachInterrupt(digitalPinToInterrupt(2), ISR, mode)
pinModeInterrupt(2, ISR, mode)
attachInterrupt(2, ISR, mode)
interruptAttach(2, ISR, mode)
On recent Arduino cores, you must use attachInterrupt(digitalPinToInterrupt(pin), ISR, mode) to attach an interrupt to the correct CPU interrupt vector. Using the pin macro ensures portability across boards. See .
What is the default I2C (TWI) clock speed on Arduino boards?
400 kHz
100 kHz
1 MHz
10 kHz
The default I2C/TWI speed on Arduino is 100 kHz, suitable for most sensors and modules. You can increase it to 400 kHz in code if supported by your devices. See .
How can you change the PWM frequency of a pin on Arduino without external libraries?
By increasing the board clock speed
By calling analogFrequency(pin, freq)
By writing to timer control registers directly
By using digitalWriteFast()
Altering the PWM frequency requires modifying the AVR timer control registers (TCCRnA/B) to adjust prescalers or modes. High-level functions like analogWrite() do not expose frequency settings. Details at .
Which bitwise operator shifts bits to the left in C/C++?
<<
|
>>
&
The << operator shifts bits of a value to the left by a specified number of positions, effectively multiplying by powers of two. The >> operator shifts bits to the right. More in the C operator reference at .
What is the correct way to start an SPI transaction with custom settings?
SPI.openTransaction(settings)
SPI.startTransaction(settings)
SPI.beginTransaction(settings)
SPI.initTransaction(settings)
To configure custom SPI settings (clock speed, data order, mode), use SPI.beginTransaction(SPISettings). This ensures atomic transfers and correct configuration. See .
What is the recommended maximum current draw per I/O pin on an Arduino UNO for safe operation?
40 mA
20 mA
5 mA
60 mA
The absolute maximum current per I/O pin is 40 mA, but the recommended safe current is 20 mA to avoid stressing the microcontroller. Exceeding this can damage the ATmega328P. Refer to the electrical specifications at .
How much EEPROM storage is available on the Arduino UNO?
512 bytes
2 KB
1 KB
4 KB
The ATmega328P on the Arduino UNO provides 1 KB of EEPROM for non-volatile storage. This memory preserves data across resets and power cycles. Details at .
Which function sets the analog reference voltage to the internal 1.1V reference?
analogReference(DEFAULT)
analogSetReference(INTERNAL_1V1)
analogRef(INTERNAL_1V1)
analogReference(INTERNAL)
To use the built-in 1.1V reference for analogRead(), call analogReference(INTERNAL). DEFAULT uses the 5V supply, and other variants are not valid. See .
How would you configure Timer1 in CTC mode with a prescaler of 64 to generate a 1 kHz interrupt on Arduino UNO?
TCCR1A = _BV(WGM10); TCCR1B = _BV(WGM12) | _BV(CS12); OCR1A = 125; TIMSK1 = _BV(OCIE1B);
TCCR1A = 0; TCCR1B = _BV(WGM12) | _BV(CS11); OCR1A = 249; TIMSK1 = _BV(OCIE1A);
TCCR1A = 0; TCCR1B = _BV(WGM12) | _BV(CS11) | _BV(CS10); OCR1A = 249; TIMSK1 = _BV(OCIE1A);
TCCR1A = _BV(WGM11); TCCR1B = _BV(WGM13) | _BV(CS10); OCR1A = 1023; TIMSK1 = _BV(OCIE1A);
In CTC mode (WGM12=1, WGM13/11/10=0) with prescaler 64 (CS11 and CS10 bits set), OCR1A must be 16MHz/(64·1000)?1 = 249. The interrupt is enabled via OCIE1A. See for details.
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Study Outcomes

  1. Understand Arduino Code Structure -

    Grasp the fundamental components of arduino test code, including setup and loop functions, to confidently approach any arduino code test.

  2. Identify Circuit Wiring Issues -

    Pinpoint common wiring mistakes and troubleshoot faulty connections in basic to advanced circuits during an arduino test.

  3. Apply Debugging Techniques -

    Use proven debugging strategies to quickly diagnose and fix errors in your arduino test code and improve your overall workflow.

  4. Analyze Sensor and Actuator Integration -

    Evaluate how sensors, motors, and other components interact within a circuit, enhancing your skills for more complex Arduino projects.

  5. Write Effective Arduino Sketches -

    Craft clear, functional sketches that meet quiz requirements and demonstrate your coding proficiency in our arduino quiz challenges.

  6. Evaluate Personal Performance -

    Assess your strengths and areas for improvement after completing the arduino test, guiding your next learning steps.

Cheat Sheet

  1. Digital and Analog Pin Basics -

    Arduino boards distinguish pins as digital (0 - 13) or analog (A0 - A5). Digital pins read HIGH/LOW states, while analog pins use a 10-bit ADC to sample voltages from 0 to 5 V. Remember "D goes Binary, A goes Analog" to keep them straight.

  2. Blink Sketch and Non-Blocking Timing -

    The classic Blink example uses digitalWrite() and delay() to flash an LED, but millis() enables non-blocking timing for multitasking. For instance, replace delay(1000) with a millis() check to update LED states without pausing your loop. This approach, endorsed by Arduino's official reference, prevents your sketch from "freezing" during waits.

  3. Ohm's Law for Safe LED Circuits -

    Use V = I × R to compute resistor values and protect LEDs: R = (Vsupply - Vforward)/Iforward. For a 5 V supply and a 2 V LED at 20 mA, R = (5 - 2)/0.02 = 150 Ω. Keep Ohm's Law formula on a sticky note - it's fundamental for every hardware quiz question.

  4. Serial Communication and Debugging -

    Serial.begin(9600) initializes UART for real-time feedback in the Serial Monitor, a vital tool for troubleshooting your arduino code test. Use Serial.print() to display variable values and execution status, helping you pinpoint logic errors. Treat the monitor like a "code stethoscope" for checking your sketch's heartbeat.

  5. PWM Output with analogWrite() -

    Pulse-Width Modulation (PWM) simulates analog voltages on digital pins (typically D3, D5, D6, D9, D10, D11) using 8-bit resolution (0 - 255). For example, analogWrite(9,128) yields ~50% duty cycle to dim an LED. Think "PWM = Pulse & Wave Magic" when you need variable brightness or motor speeds.

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