针对OV5640(16位寄存器位宽)的sccb接口

sccb不需要判断应答位

/*qin*/
module sccb_io 
(
    input           clk,
    input           rst_n,
    input           sccb_write_req,
    input           sccb_read_req,
    output          sccb_ack,//数据发送完成
    output  [7:0]   sccb_read_data,
    input   [6:0]   lut_id,
    input   [15:0]  lut_addr,
    input   [7:0]   lut_data,
 
    inout           sccb_sda,
    output      reg sccb_scl
);
/*
sccb_io u_sccb_io(
    .clk            (clk            ),
    .rst_n          (rst_n          ),
    .sccb_write_req (sccb_write_req ),
    .sccb_read_req  (sccb_read_req  ),
    .sccb_ack       (sccb_ack       ),
    .lut_id         (lut_id         ),
    .lut_addr       (lut_addr       ),
    .lut_data       (lut_data       ),
    .sccb_sda       (sccb_sda       ),
    .sccb_scl       (sccb_scl       )
);
*/
 
localparam          cmoscnt_max    = 'd2000;
localparam          cmoscnt_half   = 'd1000;
localparam          comscnt_quater = 'd1500;
localparam          IDLE     = 8'b00000000;
localparam          START    = 8'b00000001;
localparam          ID_ADDR  = 8'b00000010;
localparam          REG_ADDR = 8'b00000100;
localparam          WRITE    = 8'b00001000;
localparam          READ     = 8'b00010000;
localparam          STOP     = 8'b00100000;
 
wire              sccb_en;
wire              scl_down;
reg               scl_frame;
reg               sdo;
reg               sdir;
reg               turnflag;
reg     [7:0]     read_data;//
 
reg     [15:0]    delay;//最大值必须是cmoscnt_max的两倍以上
 
reg     [7:0]     ID_CNT;  //发送从机地址
reg     [7:0]     REG_CNT; //发送寄存器地址
reg     [7:0]     DATA_CNT;//读写地址
 
reg     [15:0]    sccb_cnt;
 
reg     [7:0]     currentstate;
reg     [7:0]     nextstate;
 
assign      sccb_en = (sccb_cnt == cmoscnt_max)?1'b1:1'b0;
assign      scl_down = (!sccb_scl && scl_frame)?1'b1:1'b0;
 
assign      sccb_sda = (sdir)?sdo:1'hz;
assign      sccb_ack = (delay == 16'd5000)?1'b1:1'b0;
assign      sccb_read_data = read_data;
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        sccb_cnt <= 'd0;
    else if(currentstate == IDLE)
        sccb_cnt <= 'd0;
    else if(currentstate == STOP)
    begin
        if(sccb_scl == 1'b1 && sdo == 1'b1)
             sccb_cnt <= sccb_cnt;
        else
            sccb_cnt <= (sccb_cnt < 2*cmoscnt_max)?sccb_cnt + 1'b1:sccb_cnt;
    end
    // else if(currentstate == START)
    // begin
    //     if(turnflag)begin
    //         sccb_cnt <= (sccb_cnt > cmoscnt_half)?'d0:(sccb_cnt + 1'b1);
    //         turnflag <= 1'b0;
    //     end
    //     else
    //         sccb_cnt <= sccb_cnt + 1'b1;
    // end
    else if(sccb_cnt == cmoscnt_max)
        sccb_cnt <= 'd0;
    else 
        sccb_cnt <= sccb_cnt + 1'b1;
        
end
 always @(posedge clk or negedge rst_n)
 begin
     if(!rst_n)
         scl_frame <= 1'b1;
     else
         scl_frame <= sccb_scl; 
 end
 
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        sccb_scl <= 1'b1;
    else if(currentstate == IDLE)
        sccb_scl <= 1'b1;
    else if(currentstate == START)
    begin
        if(sccb_cnt == comscnt_quater)
            sccb_scl <= 1'b0;
        else
            sccb_scl <= sccb_scl;
    end
    else if(currentstate == STOP)
    begin
        if(sccb_en)
            sccb_scl <= 1'b1;
        else
            sccb_scl <= sccb_scl;
    end
    else if(sccb_en)
        sccb_scl <= ~sccb_scl;
end
 
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        turnflag <= 1'b0;
    else if(currentstate == STOP && nextstate == START)
        turnflag <= 1'b1;
end
 
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)begin
        ID_CNT  <= 'd0;
        REG_CNT <= 'd0;
        DATA_CNT<= 'd0;
    end
    else begin
        ID_CNT    <= (currentstate == ID_ADDR)?((sccb_en && sccb_scl)?(ID_CNT + 1'b1):ID_CNT):'d0;
        REG_CNT   <= (currentstate == REG_ADDR)?((sccb_en && sccb_scl)?(REG_CNT + 1'b1):REG_CNT):'d0;
        DATA_CNT  <= (currentstate == WRITE || currentstate == READ)?((sccb_en && sccb_scl)?(DATA_CNT + 1'b1):DATA_CNT):'d0;
    end
end
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        sdir <= 1'b1;
    else if (sccb_scl == 1'b0 && sccb_cnt == cmoscnt_half)begin
        case(currentstate)
            IDLE:       sdir <= 1'b1;
            START:      sdir <= 1'b1;
            ID_ADDR:    sdir <= (ID_CNT == 8'd8)?1'b0:1'b1;
            REG_ADDR:   sdir <= (REG_CNT == 8'd8 || REG_CNT == 8'd17)?1'b0:1'b1;
            WRITE:      sdir <= (DATA_CNT == 8'd8)?1'b0:1'b1;
            READ:       sdir <= (DATA_CNT == 8'd8)?1'b1:1'b0;
            STOP:       sdir <= 1'b1;//(bit_cnt == )?1'b0:1'b1;
            default:    sdir <= 1'b1;
        endcase
    end
end
 
always @(posedge clk or negedge rst_n)
begin
    
end
 
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        delay <= 'd0;
    else if(currentstate == STOP)
        delay <= delay + 1'b1;
    else
        delay <= 'd0;
end
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        currentstate <= IDLE;
    else 
        currentstate <= nextstate; 
end
always @(*)
begin
    case(currentstate)
        IDLE:begin
            if(sccb_read_req || sccb_write_req)
                nextstate = START;
            else
                nextstate = IDLE;
        end
        START:begin
            if(sccb_read_req || sccb_write_req)begin    
                 if(sccb_scl == 1'b0 && sccb_cnt == cmoscnt_max)
                    nextstate = ID_ADDR;
                else
                    nextstate = START;
            end
            else
                nextstate = IDLE;
        end
        ID_ADDR:begin
            if(sccb_read_req || sccb_write_req)begin
                if(ID_CNT == 8'd9)
                    nextstate = REG_ADDR;
                else
                    nextstate = ID_ADDR;
            end
            else
                nextstate = IDLE;
        end
        REG_ADDR:begin
            if(sccb_read_req || sccb_write_req)begin
                if(REG_CNT == 8'd18)begin
                    if(sccb_write_req)
                        nextstate = WRITE;
                    else
                        nextstate = READ; 
                end
                else
                    nextstate = REG_ADDR;
            end
            else
                nextstate = IDLE;
        end
        WRITE:begin
            if(sccb_read_req || sccb_write_req)begin
                if(DATA_CNT == 8'd9)
                    nextstate = STOP;
                else
                    nextstate = WRITE;
            end
            else
                nextstate = IDLE;
        end
        READ:begin
            if(sccb_read_req || sccb_write_req)begin
                if(DATA_CNT == 8'd9)
                    nextstate = STOP;
                else
                    nextstate = READ;
            end
            else
                nextstate = IDLE;
        end
        STOP:begin
            // if(delay == 'd5000)begin
                // if(sccb_read_req || sccb_write_req)
                //     nextstate = START;
                // else
            // end
            if(delay == 'd5000)
                nextstate = IDLE;
            else
                nextstate = STOP;
        end
        default:;
    endcase
end
 
 
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)begin
        sdo <= 1'b1;
        read_data <= 'd0;
    end
    else begin
        case(currentstate)
            IDLE:begin
                sdo <= 1'b1;
            end
            START:begin
                if(sccb_cnt == cmoscnt_half)
                    sdo <= 1'b0;
                else
                    sdo <= sdo;
            end
            ID_ADDR:begin
                if(ID_CNT < 8'd7)begin
                    if(sccb_scl == 1'b0 && sccb_cnt == cmoscnt_half)
                        sdo <= lut_id[8'd6 - ID_CNT];
                    else
                        sdo <= sdo;
                end
                else begin
                    if(sccb_scl == 1'b0 && sccb_cnt == cmoscnt_half)
                    begin
                        if(sccb_write_req)
                            sdo <= 1'b0;
                        else 
                            sdo <= 1'b1;
                    end
                    else
                        sdo <= sdo;
                end
            end
            REG_ADDR:begin
                if(REG_CNT < 8'd8)begin
                    if(sccb_scl == 1'b0 && sccb_cnt == cmoscnt_half)
                        sdo <= lut_addr[8'd15 - REG_CNT];//高8位
                    else
                        sdo <= sdo;
                end
                else if(REG_CNT < 8'd17 && REG_CNT > 8'd8)begin
                    if(sccb_scl == 1'b0 && sccb_cnt == cmoscnt_half)
                        sdo <= lut_addr[8'd16 - REG_CNT];//低8位
                    else
                        sdo <= sdo;
                end
                else
                    sdo <= 1'b1;
            end
            WRITE:begin
                if(DATA_CNT < 8'd8 )begin
                    if(sccb_scl == 1'b0 && sccb_cnt == cmoscnt_half)
                        sdo <= lut_data[8'd7 - DATA_CNT];
                    else
                        sdo <= sdo;
                end
                else
                    sdo <= 1'b1;        
            end
            READ:begin
                if(DATA_CNT < 8'd8 )begin
                    if(sccb_scl == 1'b1 && sccb_cnt == cmoscnt_half)
                        read_data[8'd7 - DATA_CNT] <= sccb_sda;
                    else
                        read_data <= read_data;
                end
                else begin
                    read_data <= read_data; 
                    if(DATA_CNT == 8'd8)
                        sdo <= 1'b0;
                    else
                        sdo <= sdo;
                end
            end
            STOP:begin
                if(sccb_scl == 1'b1 && sccb_cnt == 2*cmoscnt_max)
                    sdo <= 1'b1;
                else 
                    sdo <= 1'b0;
            end
            default:;
        endcase
    end
end
 
 
endmodule