From 28ca3f4aa2d41f77020e990136cf37fe9d5eb440 Mon Sep 17 00:00:00 2001 From: GitHub Date: Fri, 15 Nov 2024 12:00:30 +0000 Subject: [PATCH] deploy: 54a1b60594a09b539ad1ec75ed2556e8e4b28c63 --- library/drivers/common/watchdog/index.html | 121 ++++++++++++++++++++- searchindex.js | 2 +- 2 files changed, 121 insertions(+), 2 deletions(-) diff --git a/library/drivers/common/watchdog/index.html b/library/drivers/common/watchdog/index.html index cb7aa673..c17efc68 100644 --- a/library/drivers/common/watchdog/index.html +++ b/library/drivers/common/watchdog/index.html @@ -101,7 +101,22 @@ @@ -210,6 +225,110 @@

Watchdog#

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Overview#

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The purpose of this class is to provide an object that can stop a simulation +run, most importantly to prevent system hangs, never ending simulation runs. +The designer of the test stimulus needs to have a good understanding of the +design under test to be able to configure the watchdog module properly. The +watchdog object can be used on the entire test stimulus or on smaller test +cases, where there is a moderate chance that the system may hang, and to +prevent such instances to happen.

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Variables#

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None are available for direct external access.

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Functions#

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function new(bit [31:0] timer, string message);#

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Creates the watchdog object. The timer variable is used to set the default +timer value after which the watchdog is triggered. This value must be set in +nanoseconds. The message value sets the default output message when the +watchdog is triggered.

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function void update_message(string message);#

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Used to update the timer value. The timer variable is used to set the new timer +value after which the watchdog is triggered.

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function void update_timer(bit [31:0] timer);#

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Used to update the watchdog message. The message value sets the watchdog output +message when this is triggered. This value must be set in nanoseconds.

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task start();#

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Starts the watchdog timer in a separate thread. This allows other code to be +run in parallel with it. When the watchdog timer reaches the wait time that was +set prior to starting of the watchdog, either with a default value or an +updated value, it is triggered, prints out the watchdog message and then the +simulation is halted. If the watchdog receives a stop event, the thread is +killed and the counting stops. This means that the watchdog will not trigger in +this instance and the simulation will not be halted.

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task stop();#

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Stops the watchdog timer when called. Used when the designer wants to stop the +watchdog timer.

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task reset();#

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Stops and then starts again the watchdog timer using the start and stop +functions.

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Usage and recommendations#

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Basic usage of the watchdog timer:

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  • Declare the watchdog timer, give an initial value for the timer and the +message. These can be changed later

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  • Update the watchdog timer value and message if needed

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  • Start the watchdog timer

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  • Add test stimulus that needs to be timed by the watchdog timer

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  • Stop the watchdog timer if the stimulus finished the process

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Important

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  • The watchdog timer value must be set higher than the time the stimulus needs +to finish the execution of the process. At the initial development of the +test stimulus, this value should be oversized by a couple times the estimated +value, to ensure that the test case has enough time to complete the process +in case the original execution time is well underestimated. After a couple of +iterations when the process execution time bounds are known, the watchdog +timer should be reduced to the value that is: highest execution time for the +process +20-30% of this time to ensure that the process can terminate +properly.

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  • Multiple instances of the same watchdog timer object should not be started, +before the previous one is stopped. This will cause multiple instances of the +same watchdog to be started in separate threads. When the stop function is +called for this watchdog timer object, it will stop all currently active +watchdog timers. To use multiple watchdog timers all at the same time, +multiple watchdog timer objects need to be created, each with its own message +and timer value. This will allow each one of these to be controlled +independently.

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Other use-cases for the watchdog timer:

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  • Repetitive test stimulus that takes a long time to finish and may cause +system hanging. In this case it is more advisable have a watchdog timer +stopped and started or reset each time a repetitive task is completed. This +allows for a stricter watchdog timer value, which may stop a hanging +simulation sooner without waiting for the whole process to finish.

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Support#

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Analog Devices, Inc. will provide limited online support for anyone +using the reference design with ADI components via +the EngineerZone FPGA reference designs forum.

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It should be noted, that the older the tools’ versions and release branches +are, the lower the chances to receive support from ADI engineers.

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