From 05d77f772317de5d925301aa11bb9a880656dd05 Mon Sep 17 00:00:00 2001 From: Josh Blum Date: Thu, 15 Apr 2010 11:24:24 -0700 Subject: moved usrp1 and usrp2 fpga dirs into fpga subdirectory --- fpga/usrp2/control_lib/simple_uart_tx.v | 60 +++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 fpga/usrp2/control_lib/simple_uart_tx.v (limited to 'fpga/usrp2/control_lib/simple_uart_tx.v') diff --git a/fpga/usrp2/control_lib/simple_uart_tx.v b/fpga/usrp2/control_lib/simple_uart_tx.v new file mode 100644 index 000000000..e11a347ed --- /dev/null +++ b/fpga/usrp2/control_lib/simple_uart_tx.v @@ -0,0 +1,60 @@ + +module simple_uart_tx + #(parameter DEPTH=0) + (input clk, input rst, + input [7:0] fifo_in, input fifo_write, output [7:0] fifo_level, output fifo_full, + input [15:0] clkdiv, output baudclk, output reg tx); + + reg [15:0] baud_ctr; + reg [3:0] bit_ctr; + + wire read, empty; + wire [7:0] char_to_send; + + medfifo #(.WIDTH(8),.DEPTH(DEPTH)) fifo + (.clk(clk),.rst(rst), + .datain(fifo_in),.write(fifo_write),.full(fifo_full), + .dataout(char_to_send),.read(read),.empty(empty), + .clear(0),.space(fifo_level),.occupied() ); + + always @(posedge clk) + if(rst) + baud_ctr <= 0; + else if (baud_ctr >= clkdiv) + baud_ctr <= 0; + else + baud_ctr <= baud_ctr + 1; + + always @(posedge clk) + if(rst) + bit_ctr <= 0; + else if(baud_ctr == clkdiv) + if(bit_ctr == 9) + bit_ctr <= 0; + else if(bit_ctr != 0) + bit_ctr <= bit_ctr + 1; + else if(~empty) + bit_ctr <= 1; + + always @(posedge clk) + if(rst) + tx <= 1; + else + case(bit_ctr) + 0 : tx <= 1; + 1 : tx <= 0; + 2 : tx <= char_to_send[0]; + 3 : tx <= char_to_send[1]; + 4 : tx <= char_to_send[2]; + 5 : tx <= char_to_send[3]; + 6 : tx <= char_to_send[4]; + 7 : tx <= char_to_send[5]; + 8 : tx <= char_to_send[6]; + 9 : tx <= char_to_send[7]; + default : tx <= 1; + endcase // case(bit_ctr) + + assign read = (bit_ctr == 9) && (baud_ctr == clkdiv); + assign baudclk = (baud_ctr == 1); // Only for debug purposes + +endmodule // simple_uart_tx -- cgit v1.2.3