RFID Garage Door Opener
Today I finished a major update to my software-only RFID decoder for the Propeller microcontroller, and I finally installed my prototype in the garage. Now I can open the garage door with my RFID badge from work, while I’m on foot or on my bike 
I’ll post some pictures once there’s some sunlight. (Edit: Took some pictures this morning)
That’s pretty awesome – I’ll be looking for it next time I come by.
I noticed in the thread you said that your badge has 512 bits of information, but only 45 bits are unique ID. What are the other 467 bits for?
This also seems like it could have potentially nifty applications for the front door, especially when you get that mini-station above the stairs set up.
Thanks!
The 512 bits figure was wrong, actually- I was missing a couple layers of encoding. After some more reverse engineering, I found those layers and now I’m reading 45 bits. So, those 467 bits were redundant- duplicates of other bits, used to improve the signal to noise ratio.
Even the 45-bit packet I have may include some redundant information, since the advertised key lengths on HID’s web site are smaller. But, at least now it’s clear that the cards just have a unique ID (and maybe a site code), and nothing that’s actually personally identifying.
–Micah
AVR/Arduino support
This looks fantastic!
Any chance of getting your reader circuit working with an Arduino or AVR based system? I could really use something like this to save on the cost of RFID reader chip. I had a look at the Paralax code… and I admit I was lost…
HID coding
The HID coding is well explained in this web:
http://pe.ece.olin.edu/projects/proxcard/prox.html
What you call “stop bit” is really an odd parity bit.
That is really cool.
Thank you very much for posting the schematics and source code.
I think I will find it really useful.
Wow, it’s been over a year since I posted this. The garage door opener is still installed and working perfectly, and I use it pretty often.
We also ended up buying some generic RFID cards recently so we can give cards to friends and family. Of course it also still works with the ID badge I have in my wallet for work
The parallax forum thread with schematics and code is there now: http://forums.parallax.com/showthread.php?t=105889