Automated Timing Analysis
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Ly, QH: AUTHOR [+2]
This is a method for describing timing relationships of electrical signals and an algorithm for comparing measured timings against these descriptions. The algorithm is implemented in a program which can be run on a PC connected to a logic analyzer.
Automated Timing Analysis
This is a
method for describing timing relationships of
electrical signals and an algorithm for comparing measured timings
against these descriptions. The algorithm is implemented in a
program which can be run on a PC connected to a logic analyzer.
verification of new hardware and software, it is
necessary to take many timing samples of interface signals and
compare them to the timing requirements of components or subsystems.
This process can be rather lengthy if it is done thoroughly and under
several environmental conditions. In some cases, timing problems may
slip through a verification test because they may only occur
infrequently and only under certain conditions, and if it is not
possible to manually check all these situations. A solution to this
problem consists of a structured way to describe the required
component timings and an automated method for comparing these
descriptions to samples obtained from a standard logic analyzer or a
simulator. A program for doing this consists of four parts:
1. A parser reads the timing descriptions, checks their syntax,
and sorts them into a consistent internal structure.
2. Device dependent routines control a logic analyzer and obtain
timing samples via a standard IEEE-488 interface.
3. A comparison routine first locates the measurement points,
then compares the measured timings with the specified required
4. A statistics gathering routine summarizes the results of many
above program and a logic analyzer, hundreds or
thousands of samples can be obtained and measured in a relatively
short time with little manual intervention.
specifications are usually given in two parts. One of
these is a graphic showing the relationship of the signals of
interest with symbols marking the specific requirements which must be
met. The other is a chart which defines the minimum and/or maximum
amount of time associated with each symbol on the graphic.
shown in Figs. 1 and 2 is for a typical dynamic
random-access memory timing specification. The syntax shown
represents the current conventions used by the program. The names
ADDR and DATA represent more than one signal.
In order to
process information from a timing specification, a
way must be devised to represent the graphical information in a
structured format. The method is as follows:
1. Each point of interest is arbitrarily assigned a number. For
example, the point at which the RAS signal goes from a high level to
a low level for the first time would be a point of interest since
measurements are to be made from that point.
2. Each symbol is defined as the distance between two of the
points identified in step 1 above.
3. Each point from step 1 is defined in terms of the conditions
of relevant signals and the relative positions of other points. For