Article ID: 000076409 Content Type: Troubleshooting Last Reviewed: 09/11/2012

Under what circumstances will toggling a pin on a Classic™ device cause the device to wake up from low power mode?


Description Following are the three ways to make a Classic device exit from low-power mode:

  1. Toggling the dedicated input at any time while the part is in low-power mode will wake the device up. Dedicated inputs are always inputs, and this will work whether the pin is used or not.
  2. Toggling an I/O pin if the pin is declared as an input will wake the device up, but only if the edge detector in the part is an input. Therefore, the design must use this pin as an input, or you can "reserve" the pin by assigning a dummy pin to a specific location. Reserving the pin will work because only the input buffer, not the logic, needs to transition.
  3. Toggling a clock pin will wake the device up but only if an internal signal toggles. (There is no edge detector on the CLK pin, so toggling a reserved and used pin will not cause the device to wake up.)

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Classic™ CPLDs



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