Question & Answer

Classification: FAQ_CLASSIFICATION

Date: FAQ_DATE

Periodic reset of WinNT parallel port

Q:

After downloading the bit file of the LEDDCD40 project to the XS40-005XL prototype board and using the XSPORT program to input test signals, I encountered a problem. Once the bit file is downloaded, the LED goes blank. I expect that this should be the case. If I wait and don't input a test signal for around 15 seconds after downloading the bit file, the LED suddenly displays the number 3. When I do send a test signal afterwards, the LED correctly decodes my binary input to the corresponding decimal number. If I don't input another test signal in the next 15 seconds, the LED display goes back to the number 3. To verify that this was not just a problem with my bit file, I instead downloaded the pre-compiled bit file from the CD. The same problem occurred as stated above. The computer I am having this problem on is running Win95. The strange thing is that when I tried this on my WinNT system at work, there was no problem. Is this a problem that you have encountered before? Please let me know what you believe may be the cause of this problem and what I can possibly do to solve it.

A:

Do you have some printer port daemon that resets the parallel port every 15 seconds? That would account for this behavior since it would set the 8 data bits to "00000000" and this would display a '3' (due to inverters on the XS Board). What mode is your parallel port in (SPP, ECP, ...)? Is the XS Board the only thing attached to your parallel port?

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