Digital clock timing: required division of the basic frequency In a standard digital clock application, to generate the “tick” that advances the seconds counter, the basic frequency must be divided down to what rate?

Digital Electronics Digital System Projects Using HDL Difficulty: Easy
Choose an option
  • A
    1 Hz.
  • B
    60 Hz.
  • C
    100 Hz.
  • D
    1000 Hz.

Answer

Correct Answer: 1 Hz.

Explanation

Introduction / Context:Whether your time base is the mains frequency (50/60 Hz) or a crystal oscillator (for example, 32.768 kHz), a digital clock requires a precise 1 Hz pulse to advance the seconds counter once per second.

Given Data / Assumptions:

  • Seconds increment once each second.
  • Higher-frequency references must be divided (prescaled).
  • Stable division ensures accurate timekeeping.

Concept / Approach:Use a frequency divider so that the output is 1 tick per second. For a 60 Hz input, divide by 60; for 32.768 kHz, divide by 32,768. The exact divider topology may use cascaded binary or BCD counters in HDL.

Step-by-Step Solution:

Identify the reference frequency.Compute division factor to reach 1 Hz.Implement counters in HDL to realize the division.Feed the 1 Hz output to the seconds counter.

Verification / Alternative check:Simulate and measure output period; confirm 1 second between rising edges.

Why Other Options Are Wrong:

  • 60 Hz/100 Hz/1000 Hz correspond to upstream references or debounce rates, not the seconds tick.

Common Pitfalls:Neglecting oscillator tolerance and temperature; consider calibration if needed.

Final Answer:1 Hz.

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