Arria10 : Remote Update IP 19.1.0 watchdog behavior

[PeterG1]

Hello. There is a question is bound to Remote Update IP 19.1.0 and the watchdog.

Having looked through the documentation of the IP there is a strong conclusion of watchdog timer
to be applied once and it is enough to write '1' into RU_RESET_TIMER register once
to stop it staying in wished application image. 

But looks like it behaves in another way and it is necessary to write RU_RESET_TIMER constantly to avoid it getting expired. Is this conduct is right and expected or there is something that goes wrong in my own case?

[FvM]

Hi,
it's the operation principle of a watchdog timer that it has to be triggered periodically if it's enabled.

[PeterG1]

Obviously you are right however there are no obstacles to put once-triggered logic and call it "watchdog timer" because of necessity to repeat step with RU_RESET_TIMER not to have reflected in the documentation.  It is worth to write about in the documentation to prevent questions like this one to break any doubt and guesses what the way it would work of.

[FvM · Accepted solution]

Hi,
I read this description of watchdog timer operation in  Remote Update Intel® FPGA IP User Guide 2023.11.29,  Table 2. Remote System Configuration Components in Intel Arria 10 and Intel Cyclone® 10 GX Devices. I think it's clear enough.

The timer begins counting after the device goes into user mode. To ensure the application configuration is valid, you must continuously reset the watchdog reset_timer within a specific duration during user mode operation.

If the application configuration does not reset the user watchdog timer before time expires, the dedicated circuitry reconfigures the device with the factory configuration and resets the user watchdog timer.

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Regards
Frank

[PeterG1]

Great Thanks. Really  I somehow  have skipped it. Nevertheless It would be grateful to have the note about it between 6 and 7 steps of the section 1.3.1.1.1 as the same as it has done after 7 one as  only it  describing all necessary steps together.