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AR# 4244

Leonardo: How to change the slew rate from Leonardo.(Fast, Nodelay)


Keywords: Leonardo, Exemplar, slew, rate, fast, nodelay

Urgency: Standard

General Description:
Leonardo currently defaults all outputs with the slew rate set
to FAST. The following describes how to change the slew rates



To set an output port with a FAST slew rate:
set_attribute -port <portname> -name FAST

To set all other output ports with a SLOW slew rate:
set xlx_fast_slew FALSE

Internal Note: Using M1.4 with Leonardo 4.2, one can not
change the slew rate to slow via the ucf file


Leonardo also default input register to NODELAY.
Here is how you can set a port with delay in Leonardo.
Say, the signal going from ibuf to IFD is called data_in.
After doing a 'READ' you can then do:

set_attribute -port data_in -name DELAY -value TRUE

Then do 'Optimize', 'WRITE', M1 etc.

Also you can specify the instance of the IFD if it is
instantiated, or also the net name.

set_attribute -instance my_ifd -name DELAY -value TRUE

set_attribute -net net_name -name DELAY -value TRUE.

You should also be able to specify the medium delay if needed
AR# 4244
Date Created 08/31/2007
Last Updated 10/05/2008
Status Archive
Type General Article