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oscar717
Observer
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Registered: ‎02-26-2020

ZCU102 - How to get access to 3 UART ports ?

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Hi,

I am trying to get access to 3 UART ports on the ZCU102 Eval Board. 2 UART should be PS and 1 UART should be PL. I have enabled the 2 PS UARTs on the Zynq UltraScale+ PS IP, and also added a AXI UART Lite to the Block Diagram.

The real problem is that I don't know how to physically get access to 3 UART at the same time because the board has only 1 micro-USB port designated for the UART. I tried connecting a micro-USB to USB hub thinking that I would get access to the other COM ports but this did not work as my PC was did not see any connection.

Any suggestions on how physically connect 3 UART to the ZCU102 ?

See images attached for a better idea of what I am describing:

Capture.PNGCapture1.PNGCapture2.PNG

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joancab
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Registered: ‎05-11-2015

The above is perfectly possible and easy to implement.

Just keep in mind the original RS-232 standard has plus and minus voltages (+/- 12V I think), you need a TTL RS-232 (0 to +V) and still need to check it matches the standard in your ZCU102 UART ports, 1V8, 2V5, 3V3, something to find out. If you can't find the right conversion you may still get away with a second voltage translator from whatever is in the ZCU102 to whatever your UART-to-RS422 needs. Being UART baud rates low (115200 ?), any delay/ jitter introduced is not going to be a problem.

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florentw
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Registered: ‎11-09-2015

Hi @oscar717 

When you connect the USB to UART micro USB cable, your computer should see 4 COM port for the ZCU102 (2 for PS UART, 1 for PL UART and one for the system controller). If you only see one, then maybe try to reinstall the drivers for the USB to UART bridge:

https://www.xilinx.com/support/answers/33569.html 


Florent
Product Application Engineer - Xilinx Technical Support EMEA
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joancab
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Registered: ‎05-11-2015

 

UART and USB are very different things. When USB took over UART, because it was so ubiquitous, things like "UART over USB" and "Virtual COM ports" were developed. In modern PCs (later than 90s) you have that by default, and in many gadgets they fit a chip that "magically" converts between UART and USB (like the FTDI ones) as no one would like the clumsy DB9 connector. 

If that is available in the ZCU102 board, it is only for the PS UARTs. So, put it simple, you cannot easily see a PL UART on the USB. 

What you still can do is take a serial-to-USB cable and connect the PL uart with that USB cable to another port in your PC.

oscar717
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Registered: ‎02-26-2020

Hi @joancab 

Thanks for clarifying the differences between UART and USB. However I am still have some questions.

The problem is that I am trying to connect two devices to the ZCU102, but these devices have a DB9 connector. I usually connect these devices to my laptop like you mentioned, with a serial-to-USB cable, but now I needto connect them to the ZCU102. I was thinking in buying some type of RS232 to LVTTL converter so that I could connect from the device to the PL IO on the ZCU102 using a UART IP.

This is the diagram of what I mentioned above:

Capture.PNG

I am open to other suggestions, do you think there is a better way to do this?

Thanks in advance for your help.

 

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joancab
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Registered: ‎05-11-2015

The above is perfectly possible and easy to implement.

Just keep in mind the original RS-232 standard has plus and minus voltages (+/- 12V I think), you need a TTL RS-232 (0 to +V) and still need to check it matches the standard in your ZCU102 UART ports, 1V8, 2V5, 3V3, something to find out. If you can't find the right conversion you may still get away with a second voltage translator from whatever is in the ZCU102 to whatever your UART-to-RS422 needs. Being UART baud rates low (115200 ?), any delay/ jitter introduced is not going to be a problem.

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oscar717
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Registered: ‎02-26-2020
Thanks for the help, I will try this solution !!
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