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AR# 3762

LogiCORE PCI - What is the functionality of the latency timer?


General Description:

The current PCI specification requires a latency timer to be implemented within the core, which will insure bus ownership for a minimum amount of time for each master.


The latency timer is measured in units of PCI clocks. Its typical values are 32 and 64 clocks (1 and 2 microseconds). The timer starts when FRAME# is asserted, and it stops when the count expires OR FRAME# is de-asserted.

The master must vacate the bus when the latency timer has expired AND GNT# is de-asserted.

AR# 3762
Date Created 08/21/2007
Last Updated 12/15/2012
Status Active
Type General Article