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Forum Index : Microcontroller and PC projects : HW WATCHDOG

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carlschneider
Senior Member

Joined: 04/08/2023
Location: South Africa
Posts: 158
Posted: 06:15pm 27 Aug 2023
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Hi there

Hopefully somebody can provide a quick clarification regarding the terminology used in referring to the Watchdog Timer functionality.

I was under the impression that the Watchdog Timer is a hardware timer forming part of the core RP2040 and not an MMBasic software function-other than MMBasic accessing the hardware registers to set and start the RP2040's hardware watchdog timer.

In the WebMite and PicoMite manuals no reference is made to HW Watchdog, it is referred to as a Watchdog [no HW moniker].

In the latest 5.07.08b12 reference is made to MM.WATCHDOG now working with the HW WATCHDOG?

Clarification would be appreciated.
Cheers Carl                                                        
Retirement is tough on Hobbies without a day job
 
matherp
Guru

Joined: 11/12/2012
Location: United Kingdom
Posts: 9126
Posted: 06:40pm 27 Aug 2023
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Prior to recent betas the only watchdog was implemented in the firmware by looking at a counter in the timer interrupt (1mSec interrupts). This is the same on all other versions of MMBasic.

It relies on the timer interrupt working

There are potential conditions that means this isn't the case.

The new functionality exists alongside the old and gives the option to use a watchdog implemented in the RP2040 silicon. This cannot fail. It does have the limitation that it must be poked at least every 8.3 seconds whereas the firmware watchdog can be set to have a practically unlimited timeout.

NOTE: 8.3 seconds may not be enough for some web operations so buyer-beware
Edited 2023-08-28 04:55 by matherp
 
carlschneider
Senior Member

Joined: 04/08/2023
Location: South Africa
Posts: 158
Posted: 07:04pm 27 Aug 2023
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Thanks Peter

I tried searching the forum for HW Watchdog and couldn't find any relevant posts, thus the question. Of course if I had searched for Watchdog HW I would have had the answer.

The link at the start of the beta thread taking one to the WebMite thread also meant I didn't read all the posts in the PicoMite thread, sorry.

In the manual there is reference to the CALL usersubname$ command (and function); where it alludes to CALL being more efficient than Case and IF Then ElseIf EndIf structures. I have been unable to find any examples of the usage of this command/function. Perhaps you could point me in the right direction?
Cheers Carl                                                        
Retirement is tough on Hobbies without a day job
 
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