Super Watchdog - timer questions

[mattgold]

Hi all
The Super Watchdog looks like what I have been looking for (without costing the earth) - I need a simple solution to manage the power on a solar project with some RPi 4B (and maybe 3B).

1) If I install the Hat and then power on the Pi, is the watchdog timer immediately active and set to pull the power to the Pi after 2 minutes? Or do the boards come disabled and we can set the timer value after we install the software ?

2) Once the software is installed, does this reset the watchdog timer regularly (and if so, how regularly) ?

3) Is there a difference between a reset, a reload and addressing the watchdog timer? These terms seem to be being used interchangeably.

4) What is the maximum value of seconds that can be passed to wdt -off ?

5) The Usage Example (github home page for wdt-rpi) has a "wdt -r" in the _else_ clause, but surely this is redundant given the first statement "var1=$(wdt -g vb)" does a reload? Or does that not count as a command 'sent' to the watchdog timer?
(I would have echo'd the voltage before the _if_ statement so the level at shutdown is recorded too)

Sorry for all the questions!
TIA

Matthew

 

[alexburcea]

1) For the watchdog to do its job you need to power the Rsspberry from the watchdog. The watchdog function is by default disabled (will keep the Raspberry power indefinitely until you start communicating with it).

2) The provided software does not do anything by itself, you have to run it from a python program or shell script, etc. There are a few usage examples on GitHub, a Python safe shutdown with SMS, and a shell script.

3) Yes, it might be used both for reloading the watchdog timer.

4) The maximum value is 65000 seconds.

5) You might have right for the late versions of the watchdog but for the early versions you have to perform the the reload explicitly, anyway does not hurt
You can modify the script as you like.

Alex.

 

[mattgold]

Thank you Alex.

If I leave the watchdog disabled (as supplied), but set the off interval via wdt -off T and then shutdown the rpi, will the watchdog power the rpi back on after T seconds? Assuming power is being supplied to the Super Watchdog via 10-24V connector.

Thanks
Matthew

 

[alexburcea]

Once you send a command to the watchdog you enable it with the default period of 270s so if not maintained (send reload command) will cut the raspberry power after 270 seconds then restore the power to the PI after T seconds. Some people use this for waking the pi once one an interval (day/ hour) to perform some task then power it off the rest of the time.