Synoptic Labs

Since my last posting, Synoptic Labs has been transplanted to new, larger digs in Sacramento, CA. As a feature of the new location, we now find ourselves with a full garage which has substantially increased our storage and work area. However, this garage opens up onto a busy downtown street with a lot of foot-traffic and a bit of that traffic is from scavengers — people who routinely comb the neighborhood (usually early in the morning) looking for recyclables or, frankly, anything that isn’t nailed down.

The door is opened by remote control and, as we’ve found on numerous occasions already, it’s all too easy to inadvertently hit the remote and open the door without realizing or just forget to close it. More than once we’ve woken up and found that the door has been wide open all night long; the fact that we haven’t lost any tools or equipment because of this astounds me.

Knowing that our luck wasn’t going to hold out forever if we keep leaving the door open, I decided something had to be done. So I hacked together a internet/mobile-phone enabled garage door monitoring system which will notify us if the door is left open during the night.

Using a simple push-switch from my electronics junk box and the parallel port on my FreeBSD server, I was able to wire the switch into the parallel port and write a very simple program to check whether or not the switch was closed. This was the first time I’ve ever hacked with the parallel port so it took me a little bit to figure out the pinouts. However, I was delighted to find that FreeBSD had the awesome ppi(4) interface for the parallel port and that it was already installed and running on my server. It only took me a couple minutes to write a simple program which could check the status of my switch and thus report on the state of the garage door.

Once that was done I whipped up a simple shell script which would run out of cron every minute and log the status of the garage door. I also whipped up a simple CGI script to so the status could be queried on the web and incorporated that into a live-status page on our private wiki. This makes it easy to check on the garage door from our mobile phones.

The final touch was setting up a Twitter account for the garage door and posting updates to that account. Now we’re able to get SMS notifications whenever the garage opens or closes. To minimize the chatter, the SMS notifications are generated only if the door is opened at night.

And thus with about $0.05 worth of parts and an afternoon’s worth of work, we now have a mobile phone/internet-enabled garage status monitoring system to alert us if we ever leave the door open again.

garagelog.sh — run out of cron every minute

#!/bin/sh

./garageis > status/garage.now

# Hour past which we'll report updates to twitter
twitstart=22
# Hour before which we'll report updates to twitter
twitstop=6

username='yourtwitteruser'
password='yourtwitterpass'

hour=`date +%H`
minute=`date +%M`

if [ ! -f status/garage.then ] || ! cmp -s status/garage.then status/garage.now; then
	if [ $hour -ge $twitstart -o $hour -lt $twitstop ]; then
		/usr/local/bin/curl -u $username:$password \
			  -d status="`cat status/garage.now`" \
			  http://twitter.com/statuses/update.xml > /dev/null 2>&1
		echo `date "+%G-%m-%d %R:%S garage: "` `cat status/garage.now` "(twittered)" >> garage.log
	else
		echo `date "+%G-%m-%d %R:%S garage: "` `cat status/garage.now` >> garage.log
	fi

	mv status/garage.now status/garage.then
elif [ $hour -eq $twitstart -a $minute -eq 0 ] && grep -q open status/garage.now; then
	# make sure we send a twitter if the garage is open when our
	# sensitivity window starts
	/usr/local/bin/curl -u $username:$password \
		  -d status="`cat status/garage.now`" \
		  http://twitter.com/statuses/update.xml > /dev/null 2>&1
fi

garageis.c — report status of garage door

#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <dev/ppbus/ppi.h>
#include <dev/ppbus/ppbconf.h>

int fd;

int
main()
{
	uint8_t  val;

	fd = open("/dev/ppi0", O_RDONLY);

	if(!fd) {
		perror(NULL);
		return(1);
	}

	// turn on data bits
	val = 0xff;
	ioctl(fd, PPISDATA, &val);

 	// read status flags.  if nBusy is 1, then garage is closed.
	ioctl(fd, PPIGSTATUS, &val);

	if ( val & nBUSY )
		printf("Garage is closed.\n");
	else
		printf("Garage is open.\n");

	// turn off data bits
	val = 0x00;
	ioctl(fd, PPISDATA, &val);

	return(0);
}

This entry was posted on Thursday, July 31st, 2008 at 1:33 pm and is filed under Tinkering. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.