sequence recognizer

Question

A1) Design a sequence recognizer (Mealy machine) for a sequence of ‘00101’. Look at the following

example.

Input X: 0010 0101 1010 1110 1011 0010 1100 0101 1011 ...

Output Z: 0000 0001 0000 0000 0000 0000 1000 0001 0000 ...

- Draw a state diagram.

- Draw a state table.

- Find input equations and output equations.

- Design a circuit by using D flip-flops.

- Implement the circuit on a Basys3 board.

- The sequence (data) input X should be given by one of the push buttons on the FPGA board.

- Generate a 0.5 Hz clock using a clock divider. Use one LED to show this clock so that you can

synchronize the input to this clock.

- Use two LEDs additionally, one for the data input (X) and the other for the output (Z).

DEBOUNCER

Push buttons have tricky signal behavior that causes inconsistencies in the design. When the push button

is activated, it generates glitches before reaching stable state as shown in Figure 1. Therefore, there is a

need of stabilizer circuit design, in other words ‘debouncer’. A debouncer circuit absorbs glitches and

produces stable signal behavior.

In this lab, you will need to create a debouncer design as given in Figure 1 as an IP block, and insert it

between the push button and the circuit input X.

Answer 1

State diagram is a visual representation of the possible states of a system and the transitions between them. In this case, the states would represent the different parts of the sequence "00101" and the transitions would be triggered by the input X.

A state table is a table that lists all the possible states of a system and the output or next state for each possible input.

The input and output equations are mathematical expressions that describe the relationship between the input and output signals of a circuit. In this case, the input equations would describe how the input X changes the current state of the circuit, and the output equations would describe how the current state of the circuit determines the output Z.

A circuit designed using D flip-flops would involve using D flip-flops to store the current state of the circuit and to trigger transitions between states based on the input X.

To implement the circuit on a Basys3 board, you would need to write the necessary code in a hardware description language such as VHDL or Verilog and then use a tool such as Xilinx ISE to program the FPGA on the board.

The debouncer circuit is a circuit that is added to the input of the system to stabilize the input signal, in order to avoid inconsistencies caused by the push button's behavior. The debouncer circuit needs to absorb glitches and produce stable signal behavior.