T7_T11

A DAC0808 circuit produces a distorted sine wave when fed from PIC. What is the most probable software-level cause?

• Incorrect reference voltage
• Lookup table values not properly sequenced
• DAC input pins shorted
• Missing analog filter

In embedded waveform generation using DAC, which C programming strategy ensures continuous waveform output without delay blocking?

• Using nested loops for timing
• Using timer interrupt-based update of DAC data
• Using ADC interrupt
• Using NOP delays between writes

A student connects LEDs directly to PORTC pins without resistors. What is the most likely outcome?

• Brighter LED output
• Possible port damage due to overcurrent
• Automatic current limiting
• Faster blinking rate

In designing a simple home protection system using embedded C, which function of PIR sensor output is typically used in the code?

• It acts as an analog feedback to PWM
• It generates an external interrupt signal
• It enables UART communication
• It resets watchdog timer

While designing an embedded LED display board using PIC18F4520, TRISB is configured as 0x00. What is the effect of this setting on LED control?

• All LEDs connected to Port B can now be driven as outputs
• All LEDs connected to Port B are disabled
• All Port B pins act as inputs for the LED
• Port B becomes analog input-only

An engineer connects a 4-bit LCD to PORTD of a PIC and notices garbled characters on display. Which of the following is the most likely cause?

• Incorrect TRISD configuration
• LCD not initialized in correct mode (0x28)
• Wrong data delay between nibbles
• All of the above

When interfacing a keypad to PORTB, why is configuring internal pull-ups critical?

• To prevent false key detections due to floating inputs
• To increase debounce speed
• To enable analog readings from keys
• To make keys more sensitive

A motion detector using PIR sensor connected to RA1 continuously triggers even when no motion occurs. Which fix is most effective?

• Enable RA1 as analog input
• Configure RA1 as digital input and stabilize power lines
• Reduce PIR voltage supply
• Disable ADC module

In a home automation project, a buzzer connected to RC2 fails to turn OFF after trigger. Which embedded C technique helps prevent this issue?

• Polling loops for each condition
• Timer interrupt–based control logic
• Direct port toggling without delay
• Nested delay loops

While debugging a PIC test board, no digital outputs are observed. Oscillator settings are correct. What should be verified next?

• Check configuration of LAT vs PORT registers
• Verify that all TRIS bits are cleared for output ports
• Inspect EEPROM configuration
• Run ADC calibration