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alfik |
/*
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* This file is subject to the terms and conditions of the BSD License. See
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* the file "LICENSE" in the main directory of this archive for more details.
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*
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* Copyright (C) 2014 Aleksander Osman
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*/
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module card_read(
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input clk,
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input rst_n,
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//
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input operation_read,
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input operation_sector_last,
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output operation_sector_update,
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output operation_finished_ok,
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output operation_finished_with_error,
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//
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output cmd_ready,
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output [5:0] cmd_index,
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output [31:0] cmd_arg,
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output [7:0] cmd_resp_length,
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output cmd_resp_has_crc7,
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input reply_ready,
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input [135:0] reply_contents,
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input reply_error,
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//
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output write_start,
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output write_next,
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output [31:0] write_data,
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input write_done,
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//
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output rd_async_start,
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output rd_async_abort,
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input rd_data_done,
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input rd_data_last_in_sector,
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input [31:0] rd_data,
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input rd_error,
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//
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input [31:0] sd_address,
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//
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input current_dat0,
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//
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output stop_sd_clk
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);
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//------------------------------------------------------------------------------
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localparam [2:0] S_IDLE = 3'd0;
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localparam [2:0] S_CMD18 = 3'd1;
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localparam [2:0] S_WAIT_FOR_DATA = 3'd2;
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localparam [2:0] S_CMD12 = 3'd3;
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localparam [2:0] S_WAIT_FOR_DAT0 = 3'd4;
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localparam [2:0] S_FAILED_CMD12 = 3'd5;
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wire prepare_cmd18 = state == S_IDLE && operation_read;
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wire valid_cmd18 = reply_contents[45:40] == 6'd18 && reply_contents[39:27] == 13'd0 && reply_contents[24:21] == 4'b0; //command index; R1[31:19] no errors; R1[16:13] no errors
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wire stop_because_of_error = (state == S_CMD18 && (reply_error || (reply_ready && ~(valid_cmd18)))) || ((state == S_CMD18 || state == S_WAIT_FOR_DATA) && rd_error);
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wire prepare_cmd12 = stop_because_of_error || (operation_sector_update && operation_sector_last);
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wire valid_cmd12_common = reply_contents[45:40] == 6'd12 && reply_contents[39:27] == 13'd0 && reply_contents[24:21] == 4'b0; //command index; R1[31:19] no errors; R1[16:13] no errors
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wire valid_cmd12 = valid_cmd12_common && current_dat0;
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wire valid_cmd12_but_busy = valid_cmd12_common && ~(current_dat0);
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wire prepare_failed_cmd12 = state == S_CMD12 && (reply_error || (reply_ready && ~(valid_cmd12_common)));
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reg [2:0] state;
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always @(posedge clk or negedge rst_n) begin
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if(rst_n == 1'b0) state <= S_IDLE;
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else if(operation_finished_with_error) state <= S_IDLE;
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else if(prepare_cmd18) state <= S_CMD18;
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else if(state == S_CMD18 && reply_ready && valid_cmd18) state <= S_WAIT_FOR_DATA;
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else if(prepare_cmd12) state <= S_CMD12;
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else if(state == S_CMD12 && reply_ready && valid_cmd12_but_busy) state <= S_WAIT_FOR_DAT0;
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else if(prepare_failed_cmd12) state <= S_FAILED_CMD12;
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else if(operation_finished_ok) state <= S_IDLE;
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end
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reg was_error;
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always @(posedge clk or negedge rst_n) begin
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if(rst_n == 1'b0) was_error <= 1'b0;
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else if(prepare_cmd18) was_error <= 1'b0;
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else if(stop_because_of_error || rd_error || prepare_failed_cmd12) was_error <= 1'b1;
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end
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wire finishing = (state == S_CMD12 && reply_ready && valid_cmd12) || (state == S_WAIT_FOR_DAT0 && current_dat0) || state == S_FAILED_CMD12;
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assign operation_finished_ok = finishing && ~(was_error);
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assign operation_finished_with_error = finishing && was_error;
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//------------------------------------------------------------------------------
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reg first_write;
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always @(posedge clk or negedge rst_n) begin
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if(rst_n == 1'b0) first_write <= 1'b0;
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else if(prepare_cmd18) first_write <= 1'b1;
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else if(write_start) first_write <= 1'b0;
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end
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reg [3:0] write_cnt;
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always @(posedge clk or negedge rst_n) begin
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if(rst_n == 1'b0) write_cnt <= 4'd0;
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else if(write_start || write_next) write_cnt <= 4'd1;
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else if(write_done) write_cnt <= 4'd0;
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else if(write_cnt > 4'd0 && write_cnt < 4'd14) write_cnt <= write_cnt + 4'd1;
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end
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assign stop_sd_clk = write_cnt == 4'd14;
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assign write_start = first_write && rd_data_done && (state == S_CMD18 || state == S_WAIT_FOR_DATA);
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assign write_next = ~(first_write) && rd_data_done && (state == S_CMD18 || state == S_WAIT_FOR_DATA);
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assign write_data = rd_data;
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assign rd_async_start = prepare_cmd18;
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assign rd_async_abort = operation_finished_ok || operation_finished_with_error;
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assign operation_sector_update = rd_data_done && rd_data_last_in_sector;
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//------------------------------------------------------------------------------
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assign cmd_ready = prepare_cmd18 || prepare_cmd12;
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assign cmd_index = (prepare_cmd18)? 6'd18 : 6'd12;
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assign cmd_arg = (prepare_cmd18)? sd_address : 32'd0; //cmd18: sector address; cmd12: stuff bits
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assign cmd_resp_length = 8'd48; //cmd18: R1; cmd12: R1b
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assign cmd_resp_has_crc7 = 1'b1;
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//------------------------------------------------------------------------------
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// synthesis translate_off
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wire _unused_ok = &{ 1'b0, reply_contents[135:46], reply_contents[26:25], reply_contents[20:0], 1'b0 };
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// synthesis translate_on
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//------------------------------------------------------------------------------
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endmodule
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