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Losspost
Beginner
1,264 Views

DE2-115/ RS-232 Broken Communication

Hi.

I am currently trying to communicate via pc to my FPGA Board. In the Simulation the Data Transmission works fine. But when I try to send Data to the real Board the Data doesnt make any sense at all. Even with the same data input to the board, i get different outputs from the FPGA Board. Anyone can help me?

 

My Code:

module UART(clk,uart_rxd,uart_txd,uart_cts,uart_rts,led_out);       input clk; input uart_rxd; output uart_txd; //Clear to send inout uart_cts; //Request to send; inout uart_rts; output[7:0] led_out; //8 times the Baud Freq. localparam baud_counter_value = 5208/8; //localparam baud_counter_value = 2500000; reg[14:0] baud_counter; //BaudClock reg baud_clock_reg; wire baud_clock; //Inital CTS/RTS register reg cts; reg rts; //Data Register reg[7:0] data; reg txd; //LED Test Register reg[7:0] led; //Counter reg[32:0] counter; //Uart State Register localparam s_IDLE = 0, s_DELAY = 1, s_DELAY_RESET =2, s_SEND = 3, s_RECEIVE = 4, s_TEST = 5, s_RECEIVE_DELAY_RESET=6, s_CLEAN_UP=7; reg[4:0] state_uart; //Baud Delay Counter //Because baud_clock is baud_clock * 8. We have to wait 8 baud_clocks for 1 baud bid at 9600baud/s reg baud_delay; reg[4:0] baud_delay_counter; reg delay; initial begin //Initialize Baud Clock baud_clock_reg = 0; baud_counter = 14'b0; cts = 0; rts = 0; data = 8'b0; led = 8'b00000001; counter = 0; baud_delay = 0; baud_delay_counter = 4'b0; //Inital state state_uart = s_IDLE; end //Creating a Baud Clock Baudrate = 9600 /*-------------------------------------------------------------------*/ always@(posedge clk) begin if(baud_counter == baud_counter_value-1) begin baud_clock_reg <= !baud_clock_reg; baud_counter = 0; end else begin baud_counter <= baud_counter +1; end end   /*-------------------------------------------------------------------*/ //Baud Delay Counter /*-------------------------------------------------------------------*/ always@(posedge baud_clock && baud_delay == 1) begin case(state_uart) s_DELAY: begin baud_delay_counter <= baud_delay_counter +1; if(baud_delay_counter == 4) begin baud_delay_counter <= 0; end end s_RECEIVE: begin baud_delay_counter <= baud_delay_counter +1; if(baud_delay_counter == 8) begin baud_delay_counter <= 0; end end s_DELAY_RESET: baud_delay_counter <= 0; s_RECEIVE_DELAY_RESET: baud_delay_counter <=0; endcase end     /*-------------------------------------------------------------------*/ //Getting Request from PC to receive Data /*-------------------------------------------------------------------*/ always@(posedge clk) begin case(state_uart) s_IDLE: begin //If Host Request to send Data //Waiting for start bit if(uart_rxd == 0) begin state_uart <= s_DELAY; end end s_DELAY: begin //Wait for 4 Baud Ticks to "sample Data" if(baud_delay_counter == 4) begin baud_delay <= 0; state_uart <= s_DELAY_RESET; end //Activate Baud Counter baud_delay <= 1; end s_DELAY_RESET: begin if(baud_delay_counter == 0) begin state_uart <= s_RECEIVE; end end //Receive the Data s_RECEIVE: begin //Waiting for one "real" baud tick baud_delay <= 1; if(baud_delay_counter == 8) begin //Setting Least Significant Bit data[0] = uart_rxd; txd <= uart_rxd; //Shift 0 bit one to the Left //= because its only getting executed after the previous line was executed //Dont Shift the Last Bit if(counter != 7) begin data = data << 1; end counter = counter + 1; state_uart <= s_RECEIVE_DELAY_RESET; end if(counter == 8) begin baud_delay <= 0; state_uart <= s_TEST; end end s_RECEIVE_DELAY_RESET: begin if(baud_delay_counter == 0)begin state_uart <= s_RECEIVE; end end s_TEST: begin led <= data; state_uart <= s_CLEAN_UP; end s_CLEAN_UP: begin data = 8'b0; counter = 0; txd <= 1; state_uart <= s_IDLE; end endcase end   /*-------------------------------------------------------------------*/     //Update Baud Clock Signal assign baud_clock = baud_clock_reg; assign uart_cts = cts; assign uart_rts = rts; assign led_out = led; assign uart_txd = txd;     endmodule

 

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JohnT_Intel
Employee
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Hi,

 

I would recommend you to try the refence design from https://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=163&No=502&PartNo=4 to confirm if there is any issue on the board or your design.​

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