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3,915 Views
Registered: ‎09-14-2016

Need help

I want to make a PCB using ARTIX-7 ["xc7a75tftg256-2"] FPGA. I have made a excel sheet for I/O's, which i need for our projects.

i was testing, compilation using these i/o's. but there are some errors. if anybody can help me regarding that please help me. i have attached here excel sheet made by me and .xdc file also made with take to reference of this excel sheet.

Errors.png
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2 Replies
balkris
Xilinx Employee
Xilinx Employee
3,900 Views
Registered: ‎08-01-2008


It seems this is custom board
check this post
https://forum.digilentinc.com/topic/968-conflicting-voltages-in-bank/

You need to verify master XDC file of your board
http://www.xilinx.com/support/documentation/application_notes/xapp554-xadc-layout-guidelines.pdf
Thanks and Regards
Balkrishan
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u4223374
Advisor
Advisor
3,897 Views
Registered: ‎04-26-2015

The FPGA pins are arranged in banks. Each bank has its own voltage rail, and they can each be at different voltages (eg. you can have one bank at 1.8V for talking to 1.8v RAM/flash, and one at 3.3V for talking to ADCs). However, within one bank, all the pins have to be the same voltage - you can't put your 1.8V and 3.3V pins on the same bank.

What you've done is specified that on Bank 14, O_FB_CLK is an LVCMOS18 pin (which tells the tool that you plan to supply that bank with 1.8V). You've also specified that on Bank 14, I_DATA_CLK is an LVCMOS25 pin (which tells the tools that you plan to supply that bank with 2.5V).

Unless you've figured out how to feed both 1.8V and 2.5V into one supply pin simultaneously, this is not going to work.

So, you need to do two things:

(1) Check those pins. If I_DATA_CLK and O_FB_CLK are connecting to the same external chip, it seems unlikely that they're at different voltages. You may just have put the wrong IOSTANDARD specifier on one pin.

(2) If those are the correct voltages, then you need to re-define your pinout in a way that doesn't cause this problem.

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