Here's my first RPi project: The Yeodem.

[jgoat]

My DSL modem gets hung up frequently, and requires rebooting, which is done by unplugging it, waiting 20 seconds, and plugging it back in. Exactly the sort of thing a robot should do. Here's my robot:

https://github.com/jimmyyeo/Yeodem (writeup in the readme, though that needs updating already)

http://www.youtube.com/watch?v=hIoNMuOyTOI (demo)

[gmc]

Nice. You could have done the same thing with a 555 timer

[PiGraham]

Nice. You could have done the same thing with a 555 timer

How does a 555 timer know if the internet is inaccessible?

A change of ISP or a new modem might be better options.

[gmc]

Whoops - my bad.

Forget why I said.

[PiGraham]

An alternative could be to slightly hack the router hardware. If it has a "connected" LED then the drive to that could trigger something like a 555 to cut power for a few seconds. A 556 dual could provide the 30 minute lock-out as well. (maybe that's pushing it with an RC circuit. 10 mins is supposed to work)

[jgoat]

Nice. You could have done the same thing with a 555 timer

I actually built it with a 555 first. I'm teaching myself electronics, linux and Python, all at once, because there are many other things I want to do with the Pi. This, so far, is a handle for learning command line arguments, SQL access (I've also worked with MySQL on an earlier thing)... I've had serious problems comprehending time functions, but I'm getting there...

but anyways, my initial thought was to use the 555 to time how long the circuit stayed open, but eventually realized it was just simpler to use two major parts and move the timing to the software. But I've been playing with the 555 anyways. :>

[jgoat]

An alternative could be to slightly hack the router hardware. If it has a "connected" LED then the drive to that could trigger something like a 555 to cut power for a few seconds. A 556 dual could provide the 30 minute lock-out as well. (maybe that's pushing it with an RC circuit. 10 mins is supposed to work)

I plan to have the server check with the clients before it resets the modem - if any report successfully communicating, no reboot.

Eventually, I'm adding a GSM module, and the server will also be a gatekeeper for external admin access to my network - the router will not accept remote logins unless the Pi gets a text message from my number first, and then login will be enable for five mins, or some such.