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joe306
Scholar
Scholar
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Registered: ‎12-07-2018

Differential Pins

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Hello, I'm using the Zynq Ultrascale+ MPSOC FPGA and I have a question about I/O pins single-ended and differential. When I was using an FPGA from another vendor if I made a pair of pins in a bank differential then it forced all the pins in the bank to be differential. Is that true for the Zynq FPGA?

In the graphic below can I make the pins single-ended I/O or diff pairs?

FPGA_Diff_Pairs.jpg

 

These EXPANxx signals are going to a expansion header. The header is for the ability to connect to yet to be designed boards which may have single-end I/O or differential I/O. This is for the reason for my question about pin configuration.

I may need some pins to be diff pairs and I may need the pins to be single-ended.

Thank you very much,

Joe

1 Solution

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joancab
Teacher
Teacher
398 Views
Registered: ‎05-11-2015

@u4223374 is correct. If you have a single signal in the top module it will be understood as single ended and can be assigned to any IO pin. For differential signals, you drop buffers like IBUFDS or OBUFDS and when pin assigning in the synthesized design, they are detected as differential pairs and you just assign the P end to a P pin so the N signal goes to the other.

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u4223374
Advisor
Advisor
429 Views
Registered: ‎04-26-2015

Xilinx FPGAs don't have that restriction - you can have differential and single-ended I/O sharing the same bank. The only restriction is that one bank = one power supply, so you can't have (for example) 3.3V single-ended and LVDS output (2.5V/1.8V) on the same bank.

joancab
Teacher
Teacher
399 Views
Registered: ‎05-11-2015

@u4223374 is correct. If you have a single signal in the top module it will be understood as single ended and can be assigned to any IO pin. For differential signals, you drop buffers like IBUFDS or OBUFDS and when pin assigning in the synthesized design, they are detected as differential pairs and you just assign the P end to a P pin so the N signal goes to the other.

View solution in original post

joe306
Scholar
Scholar
301 Views
Registered: ‎12-07-2018

Great! Thank you very much for responding to my message. 

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joe306
Scholar
Scholar
301 Views
Registered: ‎12-07-2018

Thank you very much.

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