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Registered: ‎06-15-2015

PMOD Connections for UART for access from PL


I know this question is posted in a lot of forums, but I could find answers which were very different and confusing. 

I am using a Zynq ZC702 and I would like to output the data from a logic block in the PL via UART
Following some tutorials mentioned in this community page, I changed the UART port setting in the PS to EMIO. 
Now that I can see the signals (UART TX and RX) in the I/O planning window, I am not sure what pin names (Site) to assign for the same. The reference guide does not provide any information regarding the same. 

Can anyone help me with this?  

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4 Replies
Community Manager
Community Manager
Registered: ‎07-23-2012

Are you using a daughter card to connect to UART0 or are you trying to make use of J62/63 on ZC702?

The answer to your question depends on how to you want to access UART0? In case of using a daughter card, you have to LOC TX/RX pins of UART0 to the respective pins of FMC.
Please mark the post as "Accept as solution" if the information provided answers your query/resolves your issue.

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Registered: ‎06-15-2015

Thank you for your response. 

No, I am not using a daughter card. 
I am trying to access the UART directly from the PL via the PMOD. 
As, I mentioned before, I have changed the UART setting to EMIO. Is there anything else which is to  be done other than declaring the TX and the RX pins as J62/J63 in the xdc? 
I see that these pins are shared with the User LEDs as well. Is there any switch settings that i should change for this to work? 

Your help is appreciated 

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Registered: ‎09-05-2011

That should do it. How does your XDC file look like?


With an FMC card, the following system.xdc works on zc702 board


set_property PACKAGE_PIN P20 [get_ports UART_0_txd]
set_property IOSTANDARD LVCMOS25 [get_ports UART_0_txd]
set_property PACKAGE_PIN P15 [get_ports UART_0_rxd]
set_property IOSTANDARD LVCMOS25 [get_ports UART_0_rxd]


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Registered: ‎05-12-2014



we are working on a similar project, enable the UART0 thorugh EMIO accessing PMOD2 Pins (J62). For now we have added the UART0 controller and make the Ports external and in the constraing file we declared them to


set_property PACKAGE_PIN V7 [get_ports UART_0_rxd]
set_property PACKAGE_PIN W10 [get_ports UART_0_txd]
set_property IOSTANDARD LVCMOS25 [get_ports UART_0_rxd]
set_property IOSTANDARD LVCMOS25 [get_ports UART_0_txd]


Run Synthesis, Implementation and write the bitstream have been successfull. We are using a linux system and after modifying the devicetree we are able to boot the system and see that there is a second UART (ttyPS1) available.


Writing on the serial port is possible, but for some reason we cannot measure any signals on the PMOD pins with an oscilloscope.


Please give us some advices.


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