Embedded Systems Situational MCQs - Basic to Intermediate

A temperature sensor connected to a microcontroller gives fluctuating values. What’s the first step to stabilize readings?

• Reduce microcontroller speed

• Add a capacitor and apply software filtering

• Use a smaller sensor

• Change baud rate

Your LED connected to a GPIO pin stays ON after turning OFF in code. What might be wrong?

• GPIO pin configured as input

• Using pull-down resistor

• Delay function missing

• LED polarity reversed

The microcontroller resets unexpectedly after uploading code. What might be the issue?

• Too many print statements

• Watchdog timer not reset properly

• Code size too small

• ADC not used

Your embedded system fails to boot with an SD card inserted. What’s the probable reason?

• SD card uses too much power during startup

• Sensor interference

• Weak GPIO drive

• No Wi-Fi available

A sensor connected to an analog input shows incorrect values. What should you check first?

• Change to digital pin

• ADC resolution and voltage reference

• Increase sensor range

• Use PWM

UART communication between two devices fails intermittently. What’s a common cause?

• GPIO mode

• Baud rate mismatch

• Too many interrupts

• SPI interference

A user presses a button and the LED toggles multiple times. What’s likely the issue?

• Overvoltage

• Button debounce not handled

• Delay too long

• LED wattage

You're using an 8-bit microcontroller for a large sensor matrix. It runs slowly. What can you do?

• Change to SPI display

• Optimize ISR and use port-level operations

• Reduce sensor count

• Use larger wires

The PWM fan in your embedded device spins at full speed regardless of code. What could be wrong?

• Frequency mismatch

• Incorrect PWM duty cycle or configuration

• Fan is digital

• Too much delay in loop

The microcontroller behaves erratically near high-current motors. Why?

• Wrong code

• Electromagnetic interference; needs shielding or snubber

• Wi-Fi channel conflict

• ADC overflow