I use for my home automation the node red ui with a samsung galaxy tab a on the wall. This is permanently connected to the power. As soon as I approach the Talbet, the power supply is temporarily interrupted via a motion detector and the tablet is switched on and the dashboard is displayed. This works quite well so far. However, as soon as I do not activate the tablet for several hours, only a white screen appears the next time I activate it when the motion detector interrupts the power supply. I can remove this by pressing the home button, but it is very annoying and I can not explain where the error comes from. Have you already made experiences here and can help me with the problem?
A white browser screen is generally caused by a failure in a web page's framework. In the case of Dashboard, that is Angular v1. You would need to attach developer tools to the browser to see the actual error that caused the framework to crash. Not so easy on a mobile device.
Possibly, you might be able to work round the issue if you could use some automation to reload the browser tab when the device powers up. Or possibly to kill the browser app before the device powers down so that it starts from scratch when powering up.
This may be related to Android's tenancy to sleep apps that have not been used for a while. When this happens the dashboard has to reconnect to the server. I had some similar problems some time ago but the current node red and dashboard are better. Are you using the latest dashboard and node red?
Install FullyKiosk browser on your tablet and it will be waked up with the tablet camera, no need for pir sensor.
Ps. Your camera needs a front camera for that.
Yes, that would also be an alternative. However, the idea is that when I walk up the stairs to my desk, I activate the tablet with the motion detector in the stairwell. The tablet hangs right next to the desk. Through my movements, the tablet would then turn on constantly.
Ah okay, thank you for the explanation. Is there a possibility to refresh the dashboard via e.g. an HTTP request? Or should there be a solution on the Android tablet?
Thanks for the tip. I did the update on Thursday and so far the white screen no longer occurred. Thanks a lot!
Can I just say, that is the most unique and "trekky" style solution I have ever heard of? That is so cool, unique and utterly SIMPLE that I'm going to remember to use it on something of my own. Kudos for coming up with that. I mean seriously, bravo.
With your updates seemingly fixing the issue, I would also second adding whatever you're using as your monitor app (i.e. Chrome) to the "do not idle this program" list in Android. That way if your browser ever updates and somehow overrides something in Node-Red, it will still be excluded from being idled and potentially losing it's connection.
Also, portable devices with lithium based batteries do not do well being constantly plugged in. If you have the ability, I would add a periodic "unplug" cycle to allow the battery to drain and cycle. Personal experience with a lot of battery devices (i.e. old phones, tablets, etc.) I've had doing random tasks while constantly plugged in. Otherwise, you're looking at a few months before the battery destroys itself and your device goes dark. Something I wouldn't want to see with a setup as genius as this.
This really isn't true any more for any decent device as they actively manage the battery charge.
In any case, one can assume this is a surplus device and so the batter is no longer really relevant. I've used a cheap Windows tablet as a digital picture frame for years with it plugged in permanently.
I hope that is true in this case. I've watched several "high-end" devices (think Samsung, Asus, Dell, etc.) just drop dead because the battery was so shot it couldn't even turn on. Once the battery reached depleted, they were just gone and wouldn't turn back on without a new battery to replace the old. One had a swollen battery that was bulging the display, which fortunately didn't crack. One died in three months after replacing it with a stock battery from the manufacturer. One liked to charge all day and give nothing on a meter when you checked the battery terminals. The fixes were relatively easy and then everything was back in order afterward in each case. But it's happened to too many of my devices to say it's just coincidence. Hopefully Hotte93 has much better luck with batteries than I have.
A swollen battery is generally a damaged one. But you do seem to have managed to get more than your fair share of poor devices. My experiences are far different and I've been using laptops and mobiles for more years than I care to remember now. Certainly my phones, which I always plug in overnight and consist typically of an iPhone for work and Android for personal use, seem to last longer than many people I know. Similarly, my laptops just get plugged into mains when I'm at a desk (most of the time) and left to sleep overnight still plugged in. Of course, most of the laptops I've used over the past decade have been Lenovo Thinkpad's which are renown for their robustness and I've confirmed several times with our Lenovo reps that they do active battery/power management. Similarly with our Apple reps. We've also been using Microsoft laptops and tablets too for quite a while now and I can see that they too do active battery management. Many of these devices only charge to 80% when often left on power which is a fairly optimal level for the battery. You can boost to 100% by taking them off mains and back on but left on mains, they will revert back to 80% after a while.
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