T flip-flop counter using VHDL

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In summary, the conversation discusses designing a counter using T flip-flops to count in a specific sequence. The individual needs help implementing the counter and shares their code for the T flip-flop. The expert suggests using 3 TFFs and explains the process for creating a synchronous counter. They also mention the use of a toggle bit in TFFs and note that the code provided does not include it.
  • #1
michael_mke
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I have to design a counter using T flip-flops to count in the sequence 000, 100, 111, 010, 011, 000,...(repeat).

I think I got the code for the T flip-flop but not really sure and need some help implementing the counter with this.
Any help would be great. Thanks

//T flip-flop
Code:
library ieee;
    use ieee.std_logic_1164.all;

entity tff_sync_reset is
    port (
        data  :in  std_logic; -- Data input
        clk   :in  std_logic; -- Clock input
        reset :in  std_logic; -- Reset input
        q     :out std_logic  -- Q output

    );
end entity;

architecture rtl of tff_sync_reset is
    signal t :std_logic;
begin
    process (clk) begin
        if (rising_edge(clk)) then
            if (reset = '0') then
                t <= '0';
            else
                t <= not t;
            end if;
        end if;
    end process;
    q <= t;
end architecture;
 
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  • #2
I think each TFF is used to hold a bit, so you will be using 3 TFFs. If the question was asking for synchronous counter, then the clocks of the TFFs are tied together. You will then draw a state-transistion table, then use k-map to implement the combination logic to set the input to the TFFs at each state.

The input bit that goes into a TFF is usually not called 'data' but 'toggle'. When the 'toggle' bit is 1, the TFF toggles its bit.

Your code for the TFF doesn't have this toggle bit. (It would be what you call 'data', but you didn't use it.)
 
  • #3


I would first acknowledge that the provided code for the T flip-flop appears to be correct and follows the standard IEEE library. To implement the counter with this T flip-flop, I would suggest using a structural VHDL approach, where the T flip-flop is instantiated multiple times to create a counter circuit.

The counter should have three inputs: data, clk, and reset, and one output q. The data input will be used to control the sequence of the counter, and the clk input will serve as the clock signal for the T flip-flops. The reset input will be used to reset the counter to the initial state of 000.

To count in the sequence 000, 100, 111, 010, 011, 000,...(repeat), we can use three T flip-flops, with the first one connected to the most significant bit (MSB) of the counter, the second one connected to the middle bit, and the third one connected to the least significant bit (LSB). The T flip-flops can be connected in a cascading manner, with the output of one flip-flop connected to the input of the next one.

To achieve the desired sequence, we can use the data input to control the T flip-flops. For example, to count in the sequence 000, 100, 111, 010, 011, 000,...(repeat), we can set the data input to 000, 100, 111, 010, 011, 000,... and repeat this pattern. This will cause the T flip-flops to toggle and produce the desired sequence at the output q.

In conclusion, to design a counter using T flip-flops in VHDL, we can use a structural approach and instantiate multiple T flip-flops to create a counter circuit. The data input can be used to control the sequence of the counter, and the clk input will serve as the clock signal. By setting the data input to the desired sequence, we can achieve the desired counting pattern at the output q.
 

1. What is a T flip-flop counter?

A T flip-flop counter is a sequential circuit that counts the number of input pulses it receives and outputs a binary value representing the count. It is commonly used in digital systems to keep track of events or to generate timing signals.

2. What is VHDL?

VHDL (VHSIC Hardware Description Language) is a programming language used for describing digital systems. It is commonly used for designing and simulating digital circuits, such as counters, using a hardware description methodology.

3. How does a T flip-flop counter using VHDL work?

A T flip-flop counter in VHDL consists of a T flip-flop, which toggles its output based on the input pulse, and a combinational circuit that converts the toggling output into a binary count. The combinational circuit is designed using VHDL code, specifying the logic gates and connections between them.

4. What are the advantages of using VHDL for designing a T flip-flop counter?

VHDL allows for a more systematic and efficient approach to designing digital circuits, as it allows for simulation and verification before implementation. It also provides a standardized language for hardware description, making it easier to understand and modify the code. Additionally, VHDL supports hierarchical design, allowing for easier management of complex circuits.

5. Can a T flip-flop counter using VHDL be implemented in hardware?

Yes, a T flip-flop counter designed using VHDL can be implemented in hardware using a programmable logic device, such as a field-programmable gate array (FPGA). The VHDL code is synthesized into a hardware configuration file that can be loaded onto the FPGA, allowing for the circuit to be physically realized.

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