Comparing Response Data in Software

During a software comparison application, the tester generates the stimulus data, captures the actual response data, and then performs analysis of the response data after it is stored in the host PC memory. The actual response data analysis is performed entirely in software and not in real-time.

The following steps describe software comparison in more detail.

1. Enter original test data or read the data from a file. The test data may contain both stimulus and response data.
2. The tester extracts stimulus data from the test data. 1’s and 0’s in the test data specify stimulus data; all other characters indicate that no data is generated, so the voltage drivers are disabled.
3. The digital tester generates stimulus data onto the channel and acquires the response data. The generation and acquisition operations occur in parallel. During this step, reducing the round-trip delay can be important.
4. Once the generation and acquisition are complete, the application program performs the comparison on a per bit basis in software. The final pass/fail decision is only affected by the response data acquired when an ‘H’ or ‘L’ was present in the original test data.

To perform software comparison, you must transfer all data to the host computer for post-processing, which makes this method suitable for slower-speed applications. Transferring all the data to the host computer may exceed computer bandwidth limitations if more data is to be acquired than can fit on the tester’s onboard memory. For this situation and other cases that require faster comparison rates, real-time hardware comparison may be used.