I may have actually found an alarm that might work but may require some reverse engineering if I can't get them to let me have access to the protocol.
Apparently there is a version of a Viper alarm (By Directed) that allows you to access ODBII information as well as the current alarm states and digitally setting of sensors, GPS and a bunch of other stuff. if I can interface directly into it with a computer and not require a service contract it may be worth it to use that alarm and just add some features to it.
There otherwise is an android app and you have to get a service agreement for it. I will likely try having an ARM based computer access it so I can put up a web server that can display an interactive HTML5 screen that displays all of the information needed.
I've had a few different exposures to passive RF ID tags and I though I would share my experiences.
First off, I have set up two different access control systems that use passive RFID chips. In one system, we use small key fobs. In the other system we use badges with the chips imbedded in them. The fobs and the badges both use the same technology and in fact could be used interchangeably if it was so desired. Th range on them from the tagged device to the reader is about 2-3 inches at the most.
My other exposure was in the form of the implantable chips that many people put in their pets. Most of them wind up in dogs. In my case, I put them in my llamas. Anyway, the "chip" is inside a small glass tube, maybe a bit under 0.1 inches diameter by 0.5 inches diameter. The reader is a hand held thing with a pickup coil about 5" diameter. The range is only a couple inches max.
Passive has advantages... no batteries to ever replace, but I am thinking for extended range it just doesn't cut it.
I would not waste my time and life with this. Just buy a 300$ kit.
I did it and works great.
I can make one for around $30, I just need to get the tag a little smaller. Some of us are playing around with standard short range RFID for other purposes and not just the Vehicle access idea inquired about by some forum users so the discussion will likely continue.
Hi Rick, yes passive devices powered via an RF field are short range by virtue of legal power limits and size, frequency and power consumption. The disadvantage with passive devices in a vehicle is the fact that the detector in the vehicle is also the transmitter for the power source to the Tag. Not good for long term power without some thoughtful design.
Powered version of an RFID Tag (totally different to what is now referred to as RFID) is perfect for long range access with virtually no power consumption from the vehicle. Tag battery life is claimed to be measured in years.
Thanks for the link Mark, but your website does not provide any information regarding price or what products you would actually receive. A shortfall of this system is that only one phone can be paired. I guess my wife will just have to walk. I also didnt see any info on as to what rage will the system lock/unlock the car. Is it when bluetooth is our of range/within range (i.e 10m)?