HDLBits-Fsm ps2、Fsm ps2data、Fsm serial、Fsm serialdata、Fsm serialdp

目录

Fsm ps2

Fsm ps2data

Fsm serial

Fsm serialdata

Fsm serialdp​​​​​​​

Fsm ps2

The PS/2 mouse protocol sends messages that are three bytes long. However, within a continuous byte stream, it's not obvious where messages start and end. The only indication is that the first byte of each three byte message always has bit[3]=1 (but bit[3] of the other two bytes may be 1 or 0 depending on data).

We want a finite state machine that will search for message boundaries when given an input byte stream. The algorithm we'll use is to discard bytes until we see one with bit[3]=1. We then assume that this is byte 1 of a message, and signal the receipt of a message once all 3 bytes have been received (done).

The FSM should signal done in the cycle immediately after the third byte of each message was successfully received.

module top_module(
    input clk,
    input [7:0] in,
    input reset,    // Synchronous reset
    output done); //
    parameter S0=0, S1=1, S2=2, S3=3;
    reg [1:0] state, next;

    // State transition logic (combinational)
    always @(*) begin
        case (state)
            S0: next= in[3]? S1:S0;
            S1: next= S2;
            S2: next= S3;
            S3: next= in[3]? S1:S0;
        endcase
    end

    // State flip-flops (sequential)
    always @(posed