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Raspbberry Pi computer

Posted: Mon Apr 08, 2013 6:11 am
by schlaray
What are the advantages of using the new Raspberry Pi $25 computer and what can I build with it that might be useful? Schlaray.

Re: Raspbberry Pi computer

Posted: Mon Apr 08, 2013 11:14 am
by haklesup
I only heard about it from a CNN story about it selling out very quickly. Howerver what I garnered was that it is a Linux kernel and has just about everything you need top make a complete computer except a display, it's a full system. The better model has ethernet and more memory.

If you already have experience writing Linux code and want to branch out into hardware design, this is the toolkit. If you have been hankering to make your own custom mobile computing device this is a platform since others may qualify. I think its popularity comes from being such a complete hardware platform at such a low price. You still have to be well versed in writing code but much of the hardware stuff is done.

Re: Raspbberry Pi computer

Posted: Mon Apr 08, 2013 12:37 pm
by schlaray
Thank you for your answer. My goal is to build a home security system that will connect to the internet via Netero dial-up and send email messages to another location. A text message sent to my Tracfone would also be desirable. I have been told that a stand alone computer would be necessary as a start. Do you have any thoughts or suggestions on this subject? Schlaray.

Re: Raspbberry Pi computer

Posted: Mon Apr 08, 2013 1:16 pm
by Janitor Tzap
How about a cheap used PC?
All you need is a monitor. :)

Or check some Thrift Stores, Pawn Shops, Garage Sales, or Flea Markets?

I got an old used 386SX33 computer for a guy.
I paid $5 for it at a Garage Sale, it came with everything but a printer.
The guy I got it for, was going use it as a FireWall, and network hub for the rest of his home computers.

He later, upgraded the memory to the maximum the Mother Board would take, 64 Meg.
Hooked a high end color laser printer to it.
Thus, the 386 acted as a print buffer for the other computers connected to it.

Signed: Janitor Tzap

Re: Raspbberry Pi computer

Posted: Mon Apr 08, 2013 5:54 pm
by haklesup
I doubt it has a POTS modem (or even RS232, it does have some GPIO that may be configured for serial data) but I estimate it has all the other resources you need to do this project. Actually its probably overkill. Probably easiest to just couple it with a USB stick modem if you can find a driver thats compatible.

Oh, the other thing that makes this product really cool is that the company that makes it is a Charity! Though its not immedietly clear who benefits, I think its Electronics Education that benefits from a no markup product.

A PC would be a easier platform to develop this app on but with the obviously large footprint and overhead while it has to run all the time.

You could also do this do this for similar cost with a range of development kits. All you really need are some I/O pins to monitor sensors in your security system, some flash memory to store the program, some amont of RAM for executing the program and a serial interface with a library that allows you some modem functions. You still need to provide a modem telephone interface (isolation transformer and a MOV amongst a few other components).

You don't need many buttons or a fancy display. an LED can give you status and you can connect to your development PC with a Cable (usually USB these days)

Sounds like fun and I bet it snowballs into a bigger project that you described.

Re: Raspbberry Pi computer

Posted: Tue Apr 09, 2013 7:11 am
by schlaray
I have been to the Raspberry PI forum and they have two security systems noted, one requires an ethernet connection, the other a subscription to something called Carriot. All of the applications are in Debian or some version of Linux. I'm beginning to think that I am getting in over my head. My experience has been with Pic Basic Pro programming for the PIC line of Micro's, with a little exposure to assembly language. I have experimented with the Lab-x1 and Lab-x2 boards for quite some time. A security system and a phone dialer is no problem using the above but I have been told that I need a computer to do what I want to do. Mybe I will chalange someone on the Raspberry Pi forum to figure out how to do it using a dial-up connection. Thank you for your input. Schlaray.

Re: Raspbberry Pi computer

Posted: Tue Apr 09, 2013 5:14 pm
by haklesup
you definately don't need a whole PC to do your application and with the exception of the phone line interface, a PIC with a serial interface and some I/O lines should be the bare minimum. If you leave out most of the user interface and just call it to program it or connect via a local serial port to a PC or mobile device then it would be at its simplest.

With the Pi, you would obviously need to use one of the USB ports to connect to a phone line interface but there would also be lots of things oyu don't need (like an HDMI port). I suppose the Pi would enable playing recorded voice messages easier than a PIC.

An even simpler hack just triggers the autodial in a basic phone handset, then you only have to deal with sending some data in an audio stream (acoustic coupled modem style) Stick to slow data rate and it will be easier. I imagine with a relay or two rigging a phone to go off hook and dial something then hand off to another circuit AC coupled to the line to send the data. If the data is prerecorded (in any format) then all you need to do is trigger that to start and your alarm circuit gets simplified to a sequence of timing pulses and interface to your sensors. Its not as tight as a processor controlled alarm and probably not a minimal design either but easier to design I think

What are the requirements of the recieving side?

Re: Raspbberry Pi computer

Posted: Wed Apr 10, 2013 3:41 pm
by schlaray
Let me restate the problem, I want to transmit an alarm text message via email from my home #1 to a computer located in home #2 with an internet connection. I can retreve email messages at home #2. The problem seems to be getting connected to the IP at home #1 and then sending a selected message. If an ethernet is available, you can get on the net without any problem, all I have is a dial-up connection to Netzero. Schlaray.

Re: Raspbberry Pi computer

Posted: Wed May 01, 2013 5:51 pm
by WMc
The Raspberry Pi is about the size of a credit card

Re: Raspbberry Pi computer

Posted: Thu May 02, 2013 6:11 am
by schlaray
The recent article in the May edition of Nuts & Volts about the Raspberry Pi is going to be a good starting point for my project. I wish to thank all the people who replied to my inquiry. Schlaray.