Why do I need to power cycle the EPCQ quad-serial configuration device after it has been programmed?

Description

EPCQ supports dual addressing mode: 3-byte and 4-byte addressing. If the addressing mode is not set correctly for your device, configuration may fail. Arria® II, Stratix® IV, Cyclone® IV and older devices use 3-byte addressing mode while Stratix V, Arria V and newer devices use 4-byte addressing  mode.

 

The Quartus® II programmer sets the right byte addressing mode in the non-volatile register depending on the device selected in your POF file. If you are using the Quartus II software to program your EPCQ device, after the first time EPCQ device programming, power cycle the EPCQ device. This step ensures the correct addressing mode takes effect and allows successful configuration.