Raspberry Pi Forums

I'm evaluating Raspberry Pi right now for some home automation projects. I am impressed with the 7" touch screen/ Pi 2 combination, but not so much with the Raspberian software. For an embedded application with 1G of memory, it should be entirely possible to have the system boot from SD card, but all logging functions and often changed files should reside in a ram disk.

OpenWrt does it well, but Xorg is not in the distribution. Is there another OS that manages resources well without taxing the SD card like Raspbian? I've looked through the list at elinux.org but nothing stood out. What does the forum recommend that doesn't require a class 10 SD card for reliability.

My preference would be to have a distribution that can run things like fldigi, allows custom Python programs, runs perl, lua, and/or PHP.

Thanks
Epraim

ephraim,

...not so much with the Raspberian software.

You are being unfairly dismissive of Raspian. Raspian is basically Debian for the Pi and as such works very well.

What you are after is an OS for an embedded system. That is not what Debian is targeted at. Debian is a general purpose OS for use as a desktop or development machine or whatever. It's like complaining that your Mini Cooper is not a dump truck.

Having said that Debian/Raspian makes a fine OS for embedded systems as well. We use it for such things all the time around here. Just make sure you SD card is mounded read-only and keep any temporary data in a RAM based file system. See here: https://wiki.debian.org/ReadonlyRoot it's not hard.

OpenWRT is a fine thing as well. Runs on the Raspi. But if you need X there is nothing wrong with Debian/Raspbian.

As for fldigi, Python, perl, lua, PHP, it's all there in Raspian, and a lot more.

Please differentiate between Raspbian and the images the foundation provides. The latter are very bloated.
Nothing stops you from creating a stripped-down distro with tools like raspbian-ua-netinst.

Furthermore i consider emedded Linux systems the opposite of full-blown distros with package managment - the first are single-purpose systems.
Mastering tools like buildroot or Yocto is propably the way forward for you.

ghans

ephraim wrote:all logging functions and often changed files should reside in a ram disk.

Are you serious? Where does your data go if your power goes?
I'm guess I'm logging thousands of readings a day from varous sensors and actors, probably many, many times more than that.

fruit-uk,

Where does your data go if your power goes?

Good question.

The idea is that for an embedded system that needs to be reliable, perhaps at a remote location or otherwise hard to get at and fix, it's a very good idea not to write to the same media you are booting from.

So, keep the data in RAM or, if data loss is a worry, write your data to a USB stick or whatever

Of course this is the era of "The Internet of Things" so forward your data to a server in the cloud.

Heater wrote:it's a very good idea not to write to the same media you are booting from.

I don't! Only one of my Pis has rootfs on SD, most on HDD, two on USB stick

So, keep the data in RAM or, if data loss is a worry, write your data to a USB stick or whatever

My data and logs are all backed up regulalrly

Of course this is the era of "The Internet of Things" so forward your data to a server in the cloud.

Not here it's not!

My data is mine and I will keep and look after it thanks

Yes, your data is yours.

That's the thing about clouds. They wooley and distributed. "Cloud" could be that IoT service offered my MS or whoever wants your data/money. Or it could be my server instance on AWS or Google. Or it could be my PC listening for WIFI signals at home. Or it could be that Pi in the closet that collects data from other devices around the house.

Indeed, the term is so cloudy that no-one understands exactly what anyone means by it.
Any server instance on someone else's equipment, or in any other location, is potentially insecure - let alone considering getting the data there and back

My own server is mine - and I call it a server!

Some of my servers are mine. Some of them are rented. From google and amazon


Either way data gets there over HTTPS. So I reckon the link is pretty safe. If I was worried about Google or Amazon sniffing my data I'd be encrypting it before handing over.

Thanks for the suggestions. I'll experiment with the read only root image and see if it can be bend to my will.

The reason I don't want to store data locally is because in some instances, I may have no control over the boot cycle (how much, how often) because the board may be regularly powered up and down. When the system is up, I simply either want it to forward data to a server, or hold the data until the server asks for it. The concept being that the Pi would monitor whatever it does constantly, but the server really only wants average snapshots and peak data. if the server stores data in an rrd every 5 minutes, it's no big deal to miss an occasional peak, but constantly missing them hurts. For instance, I want a Pi to manage and monitor solar data (battery voltage, bi-directional battery current, solar panel voltage, weather data, etc...) local data retrieved every 5 minuets via wireless network is fine. The Pi is overkill for that (especially with X on it), but at $35 who cares. By using the Pi, I can gain hardware standardization and the same Pi with a touch screen can also house an automation control point. Distributed computing at $35 a pop is a strong motivator for standardization. That is also why the package management is necessary. The hardware may be the same at every node (plus or minus sensors and display), the OS may be the same, but the package required for the job will be unique. it's an intriguing concept that a $35 price point makes possible. it also makes having spares on hand an easy task. Right now, I have to have a spare of at least 12 different embedded platforms.

Forwarding the data via network isn't an issue for me. I have my own WAN and the data never leaves my control. If I want more security to send it out into the cloud (for whatever reason, maybe I'm traveling and I want remote access) The Pi is powerful enough to run real time encryption. I'm liking this little board if I can get the base software to do what I want.

The controlling server would, of course, have more traditional storage like a hard drive, but with the distributed nature of the imagined system, the Pi might even be able to handle that.

When it comes to defining the "cloud" I think the definition (that I heard this week) says it all. "There is NO CLOUD, just other people's computers."

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