| ??? 03/02/10 00:03 Read: times |
#173703 - I don't want support a perticular card Responding to: ???'s previous message |
Andy Neil said:
Andy Neil said:
There are many things that may be called "proximity cards", and a number of different schemes and protocols are involved.
So the first thing you need to do is to determine exactly what card type(s) you want to support. See: http://www.8052.com/forumchat/read/173591 Hi Andy: I like to make Rfid reader similar to this. The reader constantly transmits a rather strong carrier, the tag dervies its power and clock from the carrier similar to that of an old crystal radio. The tag changes how much carrier it refects back at the reader witch I think makes the circiut across the antenna more like a short or more like an open to maybe transmit it's code. The reader and the tag both have antenna coils tuned to the carrier frequency; they possibly work something like coupled resonant transformer. The frequency that is use most of the time is 125 Khz for tag I am interested in. Best regards, Ralph Sac |
| Topic | Author | Date |
| I was wondering has any one ever | 01/01/70 00:00 | |
| Prox card reader | 01/01/70 00:00 | |
| Most (sic?) of them communicate using whats called Weigand | 01/01/70 00:00 | |
| well both | 01/01/70 00:00 | |
| What "proximity card"? | 01/01/70 00:00 | |
| Cross-Reference: RFID | 01/01/70 00:00 | |
I don't want support a perticular card | 01/01/70 00:00 |