From 7bf8a6df381a667134b55701993c6770d32bc76b Mon Sep 17 00:00:00 2001 From: Josh Blum Date: Fri, 22 Jan 2010 11:56:55 -0800 Subject: Moved usrp2 fpga files into usrp2 subdir. --- usrp2/control_lib/simple_uart_rx.v | 64 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 usrp2/control_lib/simple_uart_rx.v (limited to 'usrp2/control_lib/simple_uart_rx.v') diff --git a/usrp2/control_lib/simple_uart_rx.v b/usrp2/control_lib/simple_uart_rx.v new file mode 100644 index 000000000..debdd618b --- /dev/null +++ b/usrp2/control_lib/simple_uart_rx.v @@ -0,0 +1,64 @@ + + +module simple_uart_rx + #(parameter DEPTH=0) + (input clk, input rst, + output [7:0] fifo_out, input fifo_read, output [7:0] fifo_level, output fifo_empty, + input [15:0] clkdiv, input rx); + + reg rx_d1, rx_d2; + always @(posedge clk) + if(rst) + {rx_d2,rx_d1} <= 0; + else + {rx_d2,rx_d1} <= {rx_d1,rx}; + + reg [15:0] baud_ctr; + reg [3:0] bit_ctr; + reg [7:0] sr; + + wire neg_trans = rx_d2 & ~rx_d1; + wire shift_now = baud_ctr == (clkdiv>>1); + wire stop_now = (bit_ctr == 10) && shift_now; + wire go_now = (bit_ctr == 0) && neg_trans; + + always @(posedge clk) + if(rst) + sr <= 0; + else if(shift_now) + sr <= {rx_d2,sr[7:1]}; + + always @(posedge clk) + if(rst) + baud_ctr <= 0; + else + if(go_now) + baud_ctr <= 1; + else if(stop_now) + baud_ctr <= 0; + else if(baud_ctr >= clkdiv) + baud_ctr <= 1; + else if(baud_ctr != 0) + baud_ctr <= baud_ctr + 1; + + always @(posedge clk) + if(rst) + bit_ctr <= 0; + else + if(go_now) + bit_ctr <= 1; + else if(stop_now) + bit_ctr <= 0; + else if(baud_ctr == clkdiv) + bit_ctr <= bit_ctr + 1; + + wire full; + wire write = ~full & rx_d2 & stop_now; + + medfifo #(.WIDTH(8),.DEPTH(DEPTH)) fifo + (.clk(clk),.rst(rst), + .datain(sr),.write(write),.full(full), + .dataout(fifo_out),.read(fifo_read),.empty(fifo_empty), + .clear(0),.space(),.occupied(fifo_level) ); + +endmodule // simple_uart_rx -- cgit v1.2.3