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Fix simpleuart baud rate calculation #162

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Fix simpleuart baud rate calculation #162

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22 changes: 11 additions & 11 deletions picosoc/simpleuart.v
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Original file line number Diff line number Diff line change
Expand Up @@ -49,8 +49,8 @@ module simpleuart #(parameter integer DEFAULT_DIV = 1) (

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;
assign reg_dat_wait = reg_dat_we && (send_bitcnt != 4'h0 || send_dummy);
assign reg_dat_do = recv_buf_valid ? {24'h0, recv_buf_data} : ~0;

always @(posedge clk) begin
if (!resetn) begin
Expand All @@ -77,24 +77,24 @@ module simpleuart #(parameter integer DEFAULT_DIV = 1) (
case (recv_state)
0: begin
if (!ser_rx)
recv_state <= 1;
recv_divcnt <= 0;
recv_state <= cfg_divider == 32'h1 ? 2 : 1;
recv_divcnt <= 1;
end
1: begin
if (2*recv_divcnt > cfg_divider) begin
if (2*recv_divcnt >= cfg_divider) begin
recv_state <= 2;
recv_divcnt <= 0;
end
end
10: begin
if (recv_divcnt > cfg_divider) begin
if (recv_divcnt + 1 >= 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
if (recv_divcnt + 1 >= cfg_divider) begin
recv_pattern <= {ser_rx, recv_pattern[7:1]};
recv_state <= recv_state + 1;
recv_divcnt <= 0;
Expand All @@ -107,7 +107,7 @@ module simpleuart #(parameter integer DEFAULT_DIV = 1) (
assign ser_tx = send_pattern[0];

always @(posedge clk) begin
if (reg_div_we)
if (| reg_div_we)
send_dummy <= 1;
send_divcnt <= send_divcnt + 1;
if (!resetn) begin
Expand All @@ -116,18 +116,18 @@ module simpleuart #(parameter integer DEFAULT_DIV = 1) (
send_divcnt <= 0;
send_dummy <= 1;
end else begin
if (send_dummy && !send_bitcnt) begin
if (send_dummy && send_bitcnt == 4'h0) begin
send_pattern <= ~0;
send_bitcnt <= 15;
send_divcnt <= 0;
send_dummy <= 0;
end else
if (reg_dat_we && !send_bitcnt) begin
if (reg_dat_we && send_bitcnt == 4'h0) 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
if (send_divcnt + 1 >= cfg_divider && send_bitcnt != 4'h0) begin
send_pattern <= {1'b1, send_pattern[9:1]};
send_bitcnt <= send_bitcnt - 1;
send_divcnt <= 0;
Expand Down