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Diffstat (limited to 'ice40/benchmark/simpleuart.v')
-rw-r--r-- | ice40/benchmark/simpleuart.v | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/ice40/benchmark/simpleuart.v b/ice40/benchmark/simpleuart.v new file mode 100644 index 00000000..50808cb3 --- /dev/null +++ b/ice40/benchmark/simpleuart.v @@ -0,0 +1,137 @@ +/* + * PicoSoC - A simple example SoC using PicoRV32 + * + * Copyright (C) 2017 Clifford Wolf <clifford@clifford.at> + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + * + */ + +module simpleuart ( + input clk, + input resetn, + + output ser_tx, + input ser_rx, + + input [3:0] reg_div_we, + input [31:0] reg_div_di, + output [31:0] reg_div_do, + + input reg_dat_we, + input reg_dat_re, + input [31:0] reg_dat_di, + output [31:0] reg_dat_do, + output reg_dat_wait +); + reg [31:0] cfg_divider; + + reg [3:0] recv_state; + reg [31:0] recv_divcnt; + reg [7:0] recv_pattern; + reg [7:0] recv_buf_data; + reg recv_buf_valid; + + reg [9:0] send_pattern; + reg [3:0] send_bitcnt; + reg [31:0] send_divcnt; + reg send_dummy; + + assign reg_div_do = cfg_divider; + + assign reg_dat_wait = reg_dat_we && (send_bitcnt || send_dummy); + assign reg_dat_do = recv_buf_valid ? recv_buf_data : ~0; + + always @(posedge clk) begin + if (!resetn) begin + cfg_divider <= 1; + end else begin + if (reg_div_we[0]) cfg_divider[ 7: 0] <= reg_div_di[ 7: 0]; + if (reg_div_we[1]) cfg_divider[15: 8] <= reg_div_di[15: 8]; + if (reg_div_we[2]) cfg_divider[23:16] <= reg_div_di[23:16]; + if (reg_div_we[3]) cfg_divider[31:24] <= reg_div_di[31:24]; + end + end + + always @(posedge clk) begin + if (!resetn) begin + recv_state <= 0; + recv_divcnt <= 0; + recv_pattern <= 0; + recv_buf_data <= 0; + recv_buf_valid <= 0; + end else begin + recv_divcnt <= recv_divcnt + 1; + if (reg_dat_re) + recv_buf_valid <= 0; + case (recv_state) + 0: begin + if (!ser_rx) + recv_state <= 1; + recv_divcnt <= 0; + end + 1: begin + if (2*recv_divcnt > cfg_divider) begin + recv_state <= 2; + recv_divcnt <= 0; + end + end + 10: begin + if (recv_divcnt > cfg_divider) begin + recv_buf_data <= recv_pattern; + recv_buf_valid <= 1; + recv_state <= 0; + end + end + default: begin + if (recv_divcnt > cfg_divider) begin + recv_pattern <= {ser_rx, recv_pattern[7:1]}; + recv_state <= recv_state + 1; + recv_divcnt <= 0; + end + end + endcase + end + end + + assign ser_tx = send_pattern[0]; + + always @(posedge clk) begin + if (reg_div_we) + send_dummy <= 1; + send_divcnt <= send_divcnt + 1; + if (!resetn) begin + send_pattern <= ~0; + send_bitcnt <= 0; + send_divcnt <= 0; + send_dummy <= 1; + end else begin + if (send_dummy && !send_bitcnt) begin + send_pattern <= ~0; + send_bitcnt <= 15; + send_divcnt <= 0; + send_dummy <= 0; + end else + if (reg_dat_we && !send_bitcnt) begin + send_pattern <= {1'b1, reg_dat_di[7:0], 1'b0}; + send_bitcnt <= 10; + send_divcnt <= 0; + end else + if (send_divcnt > cfg_divider && send_bitcnt) begin + send_pattern <= {1'b1, send_pattern[9:1]}; + send_bitcnt <= send_bitcnt - 1; + send_divcnt <= 0; + end + end + end +endmodule |