Hello,
I am trying to send some data via UART. I have a shift register which
stores a value for 24 clk cycles. Meanwhile I want this value to be sent
via UART because after that the register will have another value saved
into it. Is this even possible? In a picture that I have added it's my
simulation. You can see that the value "15" is stored in SR for 24
cycles. How do I send it via UART? Thanks for any help in advance!
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`timescale 1ns / 1ps
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module flipflop(
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input wire D_1, //vhod prvi ff
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input wire f_clk, //clock
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input wire rst, //reset
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input wire en, //enable
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output reg O //izhod AND vrat
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);
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parameter N = 24;
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reg [N-1:0] SR = 0, SR_next = 0; //shift register
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reg [1:0] SR_2 = 2'b11; //drugi shift register
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reg SR_set = 1, SR_en;
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reg [N-1:0] Q_4; //shift register izhod
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reg Q_1;
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reg Q_2;
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reg Q_3;
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reg Q_3_neg; //negirana vrednost izhoda detektorja
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reg [15:0] counter = 0;
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reg [15:0] counter_reg = 0;
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reg [4:0] shift_counter = 0;
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reg [16:0] counter8ciklov = 0;
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always @(posedge f_clk or posedge rst) begin
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if (rst) begin
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Q_1 <= 0;
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end
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else if (en) begin
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Q_1 <= D_1;
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end
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end
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always @(posedge f_clk or posedge rst) begin
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if (rst) begin
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Q_2 <= 0;
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counter <=0;
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counter_reg <=0;
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end
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else if (en) begin
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Q_2 <= Q_1;
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end
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end
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always @(posedge f_clk) begin
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Q_3 <= Q_2 ;
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Q_3_neg <=~Q_3;
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O <= Q_2 & ~Q_3;
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end
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always @(posedge f_clk) begin
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if (O) begin
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counter_reg <= counter;
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counter <= 0;
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end else begin
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counter <= counter + 1;
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end
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end
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//shift register 1
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always @(posedge f_clk) begin
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if ( SR_set )
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begin
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SR <= counter_reg;
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SR_set <= 0;
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end else begin
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SR <= SR;
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end
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end
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//shift register 2
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always @(posedge f_clk)begin
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if(shift_counter == 4'b0001)begin //DODAJ ŠE && tx_busy !!!!!!!!!!!!
PEter wrote:> I am trying to send some data via UART. I have a shift register which> stores a value for 24 clk cycles. Meanwhile I want this value to be sent> via UART because after that the register will have another value saved> into it. Is this even possible?
The Shiftregister 15 bits wide. Sending via uart requires two data bytes
with 1 start and 1 stop bit each (8N1). So you will need to transmit 20
bits, and you have 24 clock cycles time.
So if the UART transmits with a bit rate ~equal to the clock rate, yes
then its possible. If the UART is slower, no.
PEter wrote:> Hello,>> I am trying to send some data via UART. I have a shift register which
maybe you should look into uart.v in the zip file you attached to your
post?
There seems to be WORKING UART implementation, so you only need to use
it, and you are done.
First I would like to thank you both for answering.
1. Can I set the speed of UART or is this a fixed max value that I have
to read in the datahseet of artix7 ? Or did you just mean the baud rate
by this ?
2. I knew it will need 2 transfers of 8 bits for data and all the stop
and start bits together shouldn't exceed the 24 clock cycles (if the
UART speed is fast enoguh). So I understand that.
3. I do have a working uart but I don't know how to implement it into my
project. At UNI we did that UART example but I don't know how to use it
in my project. I would be grateful if you could have helped me out.
Thank you again for your replys
PEter wrote:> project. At UNI we did that UART example but I don't know how to use it> in my project. I would be grateful if you could have helped me out.
you should have started so:
I have homework at the UNI where I need to use UART and I do not know
how.
Please help me with my homework.
I am sorry but this is not a homework. I am trying to build a detector
which will detect to which way the current is flowing. The only part
from the UNI is the UART part.
PEter wrote:> I am sorry but this is not a homework. I am trying to build a detector> which will detect to which way the current is flowing. The only part> from the UNI is the UART part.
Well then USE the UART.v code, the uart is there just use it.
If you do not know how to use a verilog module then use google.
PEter wrote:> As said I do not know how to implement it into my project therefore I am> trying to find help here.
And I did tell you to use google. OK I do it for you:
google: how to instatiate verilog modules
I did this for you, and did take FIRST LINK
https://www.chipverify.com/verilog/verilog-module-instantiations
it explains how to use verilog modules. Just instatiate the uart_tx
module and use it then as needed in your top-level design.
This is the code I added, since I only need to use TX. The problem is
that I dont really understand what is going on here. Im trying to do a
simulation but tx_output_signal is low at all times. Also tx_busy is set
to busy all the time.
here you should connect tx_output_signal and not use assign!!!!
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> .o_busy(tx_busy) // Connect to tx_busy
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> );
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>
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> wire tx_output_signal;
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> assign tx_output_signal = uart_tx_inst.o_tx;
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> endmodule
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>
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>
>> This is the code I added, since I only need to use TX. The problem is> that I dont really understand what is going on here. Im trying to do a> simulation but tx_output_signal is low at all times. Also tx_busy is set> to busy all the time.
this is some weird way todo things. You should have see above, used the
output signal in instantion.
how long is your VALID pulse? How long did you simulate? The UART will
send 0 for START as long as one bit time at the beginning. But BEFORE
valid going low output should be high for sure, and busy should be low
after reset before valid
PEter wrote:> I tried many things. Now even that from the forum you have sent me. I> can't figure it out.> [code]// Instantiate tx_uart module> tx_uart #(.DATA_WIDTH(8), .FREQ(10000000), .BAUD(115200)) uart_tx_inst (> .i_clk(f_clk),> .i_rst(rst),> .i_data(Q_4), // Data I want to send to UART> .i_valid(SR_en),> .o_tx(), // Connect to output (an external pin)> .o_busy(tx_busy) // Connect to tx_busy> );>
it seems your uart_tx has major issue in the code, namely the START bit
can be random length depending when you assert valid. But that is not
yet your problem, you have some more issues to solve out.
also it seems busy is never cleared.. but it should be low after reset
until valid comes, then when it asserts it is asserted forever.
maybe get some better UART IP core, that works
here you should connect tx_output_signal and not use assign!!!!
I dont know what you mean. I know that o.tx() is the serial data that
will be transmitted. I just made tx_output_signal to try to simulate it
but it didnt work.
I am running simulation for 1000ns. Data_valid should be positive when
SR_en = 1 right ? .i_valid(SR_en)
In that case, SR_en is on for 40ns so the i_valid should be the same
I just want the variables from my module that I crated to be used in the
module UART
I have SR (its counting clk cycles from ADC) which I need to be sent
via UART. This data can be sent while SR_en = 1 and meanwhile i need
tx_busy to be 1. I dont know how to do that.
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