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Strange LED's behavior in ADSP-BF537 EZ-Kit Lite board

Question asked by kigo on Oct 5, 2009
Latest reply on Oct 5, 2009 by BobK

Hi, everyone!


The problem consists in the following.

When not all processor pins that control LEDs configured as outputs then LEDs, controlled by "input" pins are subject to change their state when LEDs (controlled by "output" pins) switches. In other words non-controlled LEDs randomly (not always) copy state of controlled LEDs. When I touch input pins  of U54 and U55(that are tied to controlling LEDs processor pins) on BF537 EZ-Kit Lite board by oscilloscope probe, the non-controlled LED goes out. It makes an impression that threre are some noise pick-up from output processor pin to input processor pin. I don't now is it inherent to EZ-Kit Lite board design or to processor ADSP-BF537.