Identifying a signal on a printed circuit board under test

1. A method of identifying a signal on a printed circuit board (‘PCB’) under test, the method comprising:

transmitting a test signal from a test signal generator of an integrated circuit mounted on the PCB to an output pin of the integrated circuit, the output pin connected to a test point on the PCB;

inserting, by signal identification logic of the integrated circuit into the test signal, an identifier of the signal, wherein the identifier of the signal comprises the identity of the signal;

receiving, by a signal-identifying controller from a test probe in contact with the test point, the test signal including the identifier;

displaying, on a display of the signal-identifying controller, in dependence upon the identifier, the identity of the signal, including extracting the identity of the signal from the test signal.

2. The method of claim 1 wherein the identity of the signal comprises one or more of: a component name, a pin name, a schematic symbol name, and a signal name.

3. The method of claim 1 wherein inserting into the test signal an identifier of the signal further comprises inserting the identifier periodically at predetermined intervals.

4. The method of claim 1 wherein the identifier of the signal comprises the identity of the signal, and inserting an identifier of the signal further comprises:

demultiplexing the identifier to the output pin with a demultiplexer address; and

finding, in dependence upon the demultiplexer address in a list of signal identities, the identity of the signal.

5. The method of claim 1 wherein:

the identifier of the signal comprises only an encoded value that represents the identity of the signal;

inserting an identifier of the signal further comprises demultiplexing the identifier to the output pin with a demultiplexer address; and

the method further comprises taking, by the signal identification logic as the encoded value, the demultiplexer address.

6. The method of claim 1 wherein:

the identifier of the signal comprises only an encoded value that represents the identity of the signal; and

displaying the identity of the signal further comprises extracting the encoded value from the test signal and decoding the encoded value.

7. The method of claim 1 wherein:

the identifier of the signal comprises only an encoded value that represents the identity of the signal; and

displaying the identity of the signal further comprises extracting the encoded value from the test signal and decoding the encoded value, including finding, in dependence upon the encoded value in a list of signal identities, the identity of the signal.

8. The method of claim 1 wherein:

the method further comprises configuring the integrated circuit with an initial demultiplexer address and a demultiplexer address range; and

inserting an identifier of the signal further comprises demultiplexing the identifier to the output pin with a demultiplexer address that satisfies I <=A <=(I+R- 1 ), where I is the initial demultiplexer address, A is the demultiplexer address, and R is the demultiplexer address range.

9. Apparatus for identifying a signal on a printed circuit board (‘PCB’) under test, the apparatus comprising:

a PCB under test, including an integrated circuit mounted on the PCB, the integrated circuit comprising a test signal generator that functions by transmitting a test signal to an output pin of the integrated circuit, the output pin connected to a test point on the PCB;

the integrated circuit further comprising signal identification logic that functions by inserting, into the test signal, an identifier of the signal, wherein the identifier of the signal comprises the identity of the signal;

a test probe in contact with the test point; and

a signal-identifying controller that functions by receiving from the test probe the test signal including the identifier and displaying, in dependence upon the identifier, the identity of the signal on a display of the signal-identifying controller.

10. The apparatus of claim 9 wherein the identifier of the signal comprises the identity of the signal, and inserting an identifier of the signal further comprises:

demultiplexing the identifier to the output pin with a demultiplexer address; and

finding, in dependence upon the demultiplexer address in a list of signal identities, the identity of the signal.

11. The apparatus of claim 9 wherein:

the identifier of the signal comprises only an encoded value that represents the identity of the signal;

inserting an identifier of the signal further comprises demultiplexing the identifier to the output pin with a demultiplexer address; and

the method further comprises taking, by the signal identification logic as the encoded value, the demultiplexer address.

12. The apparatus of claim 9 wherein:

the identifier of the signal comprises only an encoded value that represents the identity of the signal; and

displaying the identity of the signal further comprises extracting the encoded value from the test signal and decoding the encoded value.

13. The apparatus of claim 9 wherein:

the identifier of the signal comprises only an encoded value that represents the identity of the signal; and

displaying the identity of the signal further comprises extracting the encoded value from the test signal and decoding the encoded value, including finding, in dependence upon the encoded value in a list of signal identities, the identity of the signal.

14. A computer program product for identifying a signal on a printed circuit board (‘PCB’) under test, the computer program product disposed upon a computer readable storage medium, the computer program product comprising computer program instructions capable, when executed, of causing automated signal-identifying apparatus to function by:

transmitting a test signal from a test signal generator of an integrated circuit mounted on the PCB to an output pin of the integrated circuit, the output pin connected to a test point on the PCB;

inserting, by signal identification logic of the integrated circuit into the test signal, an identifier of the signal, wherein the identifier of the signal comprises the identity of the signal;

receiving, by a signal-identifying controller from a test probe in contact with the test point, the test signal including the identifier;

displaying, on a display of the signal-identifying controller, in dependence upon the identifier, the identity of the signal, including extracting the identity of the signal from the test signal.

15. The computer program product of claim 14 wherein the identifier of the signal comprises the identity of the signal, and inserting an identifier of the signal further comprises:

demultiplexing the identifier to the output pin with a demultiplexer address; and

finding, in dependence upon the demultiplexer address in a list of signal identities, the identity of the signal.

16. The computer program product of claim 14 wherein:

the identifier of the signal comprises only an encoded value that represents the identity of the signal;

inserting an identifier of the signal further comprises demultiplexing the identifier to the output pin with a demultiplexer address; and

the method further comprises taking, by the signal identification logic as the encoded value, the demultiplexer address.

17. The computer program product of claim 14 wherein:

the identifier of the signal comprises only an encoded value that represents the identity of the signal; and

displaying the identity of the signal further comprises extracting the encoded value from the test signal and decoding the encoded value.