AR# 20319

LogiCORE SPI-4.2 (POS-PHY L4) - "WARNING" messages appear when NGDBuild is run with SPI-4.2 Core

Description

When I implement an SPI-4.2 design through NGDBuild, several "WARNING" messages appear.

WARNING messages that CANNOT be ignored:

Sink Core: (IOSTANDARD warnings)

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "SnkIdelayRefClk_ibufg0".

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "RStat_ibuf0".

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "RStat_ibuf1".

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "RSClk_ibuf0".

Source Core: (IOSTANDARD warnings)

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "pl4_src_clk0/sysclk_ibufg0".

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "TStat_ibuf0".

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "TStat_ibuf1".

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "pl4_src_clk0/TSClk_ibuf0".

Example design: (IOSTANDARD warnings)

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "CalClk_ibufg0".

WARNING:NgdBuild:488 - Attribute value "default" is not an accepted value for attribute "IOSTANDARD" on "LoopbackClk_ibufg0".

Solution

All undefined differential signals default to LVDS 2.5V without the internal device termination. All single-ended signals default to LVCMOS, which is unacceptable for SPI4.2 application.

In the v7.x of the SPI-4.2 Core, the I/O Standards are defined in the UCF; however, they are commented out. Please uncomment the constraints in the UCF for the status signals such as:

NET "RSClk" IOSTANDARD = LVTTL;

NET "RStat" IOSTANDARD = LVTTL;

NET "RStat" IOSTANDARD = LVTTL;

See (Xilinx Answer 20017) for other supported I/O standards.

AR# 20319
Date 12/15/2012
Status Active
Type General Article