Electronic credential reader

1. An electronic credential reader, comprising:

a credential receiver;

a unidirectional communication interface;

a bidirectional communication interface;

a plurality of external communication lines, wherein the unidirectional communication interface and the bidirectional interface are coupled to a processor via the external communication lines; and

a computer readable medium coupled to the processor;

wherein the bidirectional communication interface and the unidirectional communication interface are configured to share the plurality of external communication lines; and

wherein the computer readable medium comprises instructions that, when executed by the processor, change

from a first communication mode in which the electronic credential reader uses the unidirectional communication interface to communicate with the processor via the external communication lines

to a second communication mode in which the electronic credential reader uses the bidirectional communication interface to communicate with the processor via the external communication lines.

2. The electronic credential reader of claim 1 , wherein the bidirectional communication interface comprises an RS-485 interface.

3. An electronic credential reader, comprising:

a credential receiver;

a unidirectional communication interface;

a bidirectional communication interface;

a plurality of external communication lines;

a switch configured to selectively couple the unidirectional communication interface and the bidirectional communication interface to the plurality of external communication lines;

a processor coupled via the plurality of external communication lines to the switch, for the processor to communicate with the unidirectional communication interface and bidirectional communication interface through both the plurality of external communication lines and the switch; and

a computer readable medium coupled to the processor;

wherein the bidirectional communication interface and the unidirectional communication interface are configured to share the plurality of external communication lines; and

wherein the computer readable medium comprises instructions that, when executed by the processor, control the switch to change from

a first communication mode in which the electronic credential reader uses the unidirectional communication interface to communicate with the processor via the external communication lines to a second communication mode in which the credential reader uses the bidirectional communication interface to communicate with the processor via the external communication lines.

4. The electronic credential reader of claim 3 , wherein the unidirectional communication interface comprises an output interface.

5. The electronic credential reader of claim 3 , wherein the bidirectional communication interface comprises an RS-485 interface.

6. The electronic credential reader of claim 3 , wherein the plurality of external communication lines comprises two communication lines.

7. The electronic credential reader of claim 6 , wherein the two communication lines comprises a DATA 0 line and a DATA 1 line.

8. The electronic credential reader of claim 7 , wherein the two communication lines further comprise a RS-485 DATA (A) line and a RS-485 DATA (B) line.

9. The electronic credential reader of claim 8 , wherein the two communication lines are configured and disposed to implement an Open Supervised Device Protocol (OSDP) interface.

10. The electronic credential reader of claim 3 , wherein the computer readable medium further contains instructions, that when executed by the processor, perform the steps of:

monitoring the bidirectional communication interface for input data;

setting the electronic credential reader to a bidirectional mode upon detecting input data; and

recording a status of the bidirectional mode in a non-volatile storage.

11. An electronic credential reader, comprising:

a credential receiver;

a unidirectional communication interface;

a bidirectional communication interface;

a plurality of external communication lines, wherein the bidirectional communication interface and the unidirectional communication interface are configured to share the plurality of external communication lines;

a switch coupled to the unidirectional communication interface, the bidirectional communication interface, and the plurality of external communication lines;

a processor coupled to the switch;

a computer readable medium coupled to the processor; and

a one-time programmable fuse disposed between the unidirectional communication interface and the processor;

wherein the computer readable medium contains instructions that, when executed by the processor, perform the steps of:

monitoring the bidirectional communication interface for input data;

severing the one-time programmable fuse upon detection of input data; and

changing a communication mode of the electronic credential reader from a unidirectional mode to a bidirectional mode.

12. An electronic credential reader, comprising:

a credential receiver;

a unidirectional communication interface;

a bidirectional communication interface;

a plurality of external communication lines;

a switch coupled to the unidirectional communication interface, the bidirectional communication interface, and the plurality of external communication lines;

a processor coupled to the switch;

a computer readable medium coupled to the processor; and

wherein the bidirectional communication interface and the unidirectional communication interface are configured to share the plurality of external communication lines; and

wherein the computer readable medium contains instructions, that when executed by the processor, perform the steps of:

monitoring the credential receiver for a bidirectional status code;

changing a communication mode of the electronic credential reader from a unidirectional mode to a bidirectional mode by setting the electronic credential reader to the bidirectional mode upon detecting the bidirectional status code; and

recording the bidirectional mode in a non-volatile storage.

13. An electronic credential reader, comprising:

a credential receiver;

a unidirectional communication interface;

a bidirectional communication interface;

a plurality of external communication lines;

a switch coupled to the unidirectional communication interface, the bidirectional communication interface, and the plurality of external communication lines;

a processor coupled to the switch;

a computer readable medium coupled to the processor;

wherein the bidirectional communication interface and the unidirectional communication interface are configured to share the plurality of external communication lines, and;

wherein the computer readable medium comprises instructions, that when executed by the processor, perform the steps of:

changing a communication mode of the electronic credential reader from a unidirectional mode to a bidirectional mode;

monitoring the bidirectional communication interface for input data;

setting the electronic credential reader to a bidirectional mode upon detecting input data;

recording a status of the bidirectional mode in a non-volatile storage;

establishing a hysteresis timer;

resetting the hysteresis timer upon reception of a bidirectional message; and

reverting the electronic credential reader to a hunt mode upon expiry of the hysteresis timer.

14. A computer-implemented method for configuring an electronic credential reader, comprising:

initializing the electronic credential reader in a unidirectional communication mode;

transmitting received credential information from the electronic credential reader to a processor via a unidirectional communication interface while in the unidirectional communication mode;

monitoring a bidirectional communication interface for input data; and

setting the electronic credential reader, upon detecting input data on the bidirectional communication interface, from the unidirectional communication mode to a bidirectional communication mode in which any further received credential information is transmitted from the electronic credential reader to the processor via a bidirectional communication interface.

15. A computer-implemented method for configuring an electronic credential reader, comprising:

initializing the electronic credential reader in a hunt mode;

transmitting received credential information via a unidirectional communication interface while in hunt mode;

monitoring a bidirectional communication interface for input data; and

setting the electronic credential reader to a bidirectional mode upon detecting input data on the bidirectional communication interface; and

recording a bidirectional mode status in a non-volatile storage.

16. The method of claim 15 , further comprising reverting to the hunt mode upon detection of a reset message on the bidirectional communication interface.

17. The method of claim 15 , further comprising reverting to the hunt mode upon detection of a status code from a credential.

18. The method of claim 15 , further comprising permanently disconnecting the unidirectional communication interface upon setting the electronic credential reader to the bidirectional mode.

19. The method of claim 18 , wherein permanently disconnecting the unidirectional communication interface comprises blowing a one-time programmable fuse.

20. The method of claim 15 , further comprising reverting to the hunt mode upon expiry of a hysteresis timer.