So, here’s an idea that I’ve been toying around with for a while.
I’ve been dong some development on a pair of Soekris embedded Linix boards I bought to use as a firewall/router and WAP. So, naturally, my interest in embedded systems is piqued. I know that there are some smaller embedded Linux devices out there. So, the idea is as follows:
Get an embedded Linux box that is either PoE or uses a hardwired connection with a wall-wart, or better yet, uses both, so it can be designed to have PoE as the primary power, with a 9v battery backup (ok, it won’t run too long, but can handle minor power losses if the PoE switch isn’t on a UPS).
Attach to it a clock-style LED display, or a matrix LED display, and an additional really bright red LED, both controlled by software (serial or GPIO).
The system has one RJ-45 connector for Ethernet (10-BaseT) and a serial console. The console is a captive login to a setup program to define IP, etc. but by default uses DHCP.
Plug it in, and it queries your DHCP server for an NTP server (or in the absence of one, uses a default Stratum 2). We re-update the time every day or so. Now, you have an accurate-to-the-second clock.
We add a speaker to the box, and have a few default built-in MP3s or WAVs for alarm tones, and add a GPIO “snooze” and “off” button.
The serial console allows setting a daily alarm or two, as well as selecting one of the default tones.
The Geekier Part: The alarm clock is controlled by a script called by a Cron job. Now, we add the miniserv web server and a PHP admin gateway. Login via a password (user-selectable) and we can upload new audio files for alarms, as well as adding alarms via the web as cron jobs - now I can program in my class schedule, and automatically have an alarm at the right time each day of the week!
The Geekiest Part: Remember the matrix display and that additional really bright LED? We setup simple communication between machines via SNMP or a script on the clock (called with an Expect script on a remote machine) and we can activate the super-bright LED, a custom sound, and even a scrolling message on the LED display (alternates between message and time, of course) for critical events. Now, when the servers go down, I have another device (in addition to the SMS alerts on my cell) to tell me to wake up and deal with it. If we want to get even more fancy, we can enable a feature through the serial console or web interface that emits a loud tone for a few seconds and blinks the LED if PoE is lost, or we can’t ping a user-selectable address for more than, say, one minute.
I guess I have too much free time on my hands..
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