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2,893 Views
Registered: ‎03-11-2018

How to send a data using AXI UARTlite ?

Hi,

 

I am trying to use AXI Uartlite IP to send some data to COM port of Nexys video board. I went through PG142 and PG155 product guides and figured out the way to initialize different ports of the IP.

 

The AXI Uartlite is configured as follows.

 

CLK 1MHz, baud rate 9600, data bits 8

 

S_AXI_wvalid <= '1';

 

S_AXI_wstrb <= '1';

 

S_AXI_awvalid <= '1';

 

S_AXI_aresetn <= '1';

 

S_AXI_awaddr <= "0100";

 

S_AXI_wdata <= "00000000000000000000000001010011";

 

When I simulate, the TX port output of AXI Uartlite just remains ‘X’ state instead toggling as per S_AXI_wdata. I have simulated up to 4 seconds and ll the values are initialized from the beginning of  simulation.

 

Am I missing any configuration setting? or anything needs to be carried out to get the data at TX port ?

 

Help is much appreciated.

 


Regards,
Subash

5 Replies
Scholar dpaul24
Scholar
2,874 Views
Registered: ‎08-07-2014

Re: How to send a data using AXI UARTlite ?

elesuba@nus.edu.sg,

 

In my opinion you are not driving the axi4lite signals properly.

 

The UARTLite comes with an example_design. Study that and make sure you understand how the test-bench in this eg_design is driving data into this core. Later apply this concept to drive your own data into the core.

 

Read Chapter 5 of the UARTLite spec.

Read the AXI4Lite spec.

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Moderator
Moderator
2,858 Views
Registered: ‎07-31-2012

Re: How to send a data using AXI UARTlite ?

Hi elesuba@nus.edu.sg,

 

Please try using AXI UART lite IP example design and simulate it to understand the AXI signals behaviors.

 

Regards

Praveen


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2,800 Views
Registered: ‎03-11-2018

Re: How to send a data using AXI UARTlite ?

Thanks for your relies @dpaul24 and @pvenugo

 

 I figured out the issue. It seems S_axis_resetn should be pulled high after few nano seconds. In my simulation, i kept it high from the starting which resulted in output high impedance state.

Regards,

Subash

0 Kudos
Scholar dpaul24
Scholar
2,791 Views
Registered: ‎08-07-2014

Re: How to send a data using AXI UARTlite ?

i kept it high from the starting which resulted in output high impedance state.

 

Glad that you found the error.

yes, one must always respect *reset_n, which must be low for a few clk cycles before it can be de-asserted.

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FPGA enthusiast!
All PMs will be ignored
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Moderator
Moderator
2,782 Views
Registered: ‎07-31-2012

Re: How to send a data using AXI UARTlite ?

Thanks!

 

Please close the thread if you resolved the issue by marking the solution.

 

Regards

Praveen


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