I have no experience with the SwitchDoc, but it looks like you will also need a relay (or preferable a solid state device) for full, cold boot operation (i.e. to remove the power from the Pi and properly reboot).JimKD1YV wrote:...so I need near perfect reliability...Does anybody have any experience with this device? Are there any others that people recommend?
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sudo apt-get install stress stress -c 50 # load CPU stress -m 500 --vm-bytes 1M # load RAM
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sudo kill -STOP $(pidof watchdog)
I have experience and could do a lot. I'm trying not to invest the time and effort if this wheel has already been invented. I also do not own a PIC programmer, nor wish to learn all of the nuances of another PIC family.SteveDee wrote: You could make your own if you have a little experience.
You could use a cheap PIC as the watchdog as shown in this simple block diagram.
If the heating system fails and the pipes freeze and burst, there can easily be tens of thousands of dollars worth of damage. Not life-threatening, but not a risk I want to take.Reliability needs to be seen in context: you want your heating system to be reliable for years to come, but nobody dies if it falls over.
Not the HVAC. It's not even connected at the moment, it's on the workbench running in simulated mode with only the heat sensor and SSD relays attached. I'm running a 1500 mA power cube, so it should be more than sufficient.Why does your Pi lock-up? Anything to do with electrical noise when switching HVAC?
Always a question. I am running a python package written by another experimenter. I am tweaking it and trying to understand it as I go.The other big question mark is the software...
So you've carried out a risk assessment, and you have a $35 RaspberryPi pc, set against potentially $10,000's damage if the system fails.JimKD1YV wrote:...If the heating system fails and the pipes freeze and burst, there can easily be tens of thousands of dollars worth of damage. Not life-threatening, but not a risk I want to take.
I'd suggest you run your Pi without your controller software running for (say) at least 48hrs. If it doesn't crash, its probably your code.SteveDee wrote:Why does your Pi lock-up?
The Pi will give clues, but only for detectable conditions. However, if it hangs and the Task Manager graph (in the status bar) shows 100%cpu then there is probably a process keeping it busy.Part of the problem with the Pi is that it really does not give any clues about its failure....
I have had the Pi B lockup even with the watchdog in place. In at least one case it was due to a broken cifs mount. This was the #1 cause of stability issues I had on the Pi B, if the wifi connection fluctuated enough the cifs mount would become broken, and the age old issue of cifs mounts hanging would occur. Since my Pi uses that mount to store its recorded videos, this was a bit of an issue.TimG wrote:The built-in watchdog is a hardware device, so if it failed it's likely to be a configuration problem: either the hardware was not initialised on boot, or the Pi did not crash badly enough to prevent the software daemon from continuing to reset the watchdog's hardware timer.
A couple things I'd like to point out.JimKD1YV wrote: If the heating system fails and the pipes freeze and burst, there can easily be tens of thousands of dollars worth of damage. Not life-threatening, but not a risk I want to take.