In the keypad HDL encoder, NANDing of the columns is used to activate the freeze bit.

More Questions from Digital System Projects Using HDL

• In the keypad HDL encoder, the ts bit array represents a tristate buffer.
• In the digital clock project, a MOD-60 BCD counter is made from a MOD-10 counter cascaded to a MOD-6 BCD counter.
• In the keypad HDL encoder, as long as all columns are high the ring counter is enabled and counting.
• In the digital clock project, the ENT input and RCO output can be used for synchronous counter cascading.
• In the digital clock project, when it is 11:59:59, AND gate 1 detects that the tens of hours is 1 and the edge trigger clock moves the display to 12:00:00.
• In the keypad HDL encoder, after releasing a key the ring counter resumes its counting sequence.
• In the frequency counter, a pulse shaper block is needed to ensure that the unknown signal, whose frequency is to be measured, will be compatible with the clock input for the counter block.
• The frequency counter measures frequency by enabling a counter to count the number of pulses of the incoming waveform during a precisely specified period of time called the sampling time.
• The full-step sequence always has two coils of the stepper motor energized in any state of the sequence and typically causes 30° of shaft rotation per step.
• In the digital clock project, the AHDL block codes are connected using graphic design files.

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