Configuration Handbook - Kamami.pl

Configuring APEX II DevicesTable 6–10 describes the optional configuration pins. If these optionalconfiguration pins are not enabled in the Quartus II software, they areavailable as general-purpose user I/O pins. Therefore duringconfiguration they function as user I/O pins, which means they are tristatedwith weak pull-up resistors.Table 6–10. Optional Configuration PinsPin Name User Mode Pin Type DescriptionCLKUSRN/A if option is on. I/O ifoption is off.InputOptional user-supplied clock input.Synchronizes the initialization of one ormore devices. This pin is enabled by turningon the Enable user-supplied start-up clock(CLKUSR) option in the Quartus II softwareINIT_DONEN/A if option is on. I/O ifoption is off.Output open-drainStatus pin. Can be used to indicate whenthe device has initialized and is in usermode. When nCONFIG is low and during thebeginning of configuration, the INIT_DONEpin is tri-stated and pulled high due to anexternal 1-kΩ pull-up resistor. Once theoption bit to enable INIT_DONE isprogrammed into the device (during the firstframe of configuration data), theINIT_DONE pin will go low. Wheninitialization is complete, the INIT_DONEpin will be released and pulled high and theFPGA enters user mode. Thus, themonitoring circuitry must be able to detect alow-to-high transition. This pin is enabled byturning on the Enable INIT_DONE outputoption in the Quartus II software.DEV_OEN/A if option is on. I/O ifoption is off.InputOptional pin that allows the user to overrideall tri-states on the device. When this pin isdriven low, all I/O pins are tri-stated; whenthis pin is driven high, all I/O pins behave asprogrammed. This pin is enabled by turningon the Enable device-wide output enable(DEV_OE) option in the Quartus II software.Optional pin that allows you to override allclears on all device registers. When this pinis driven low, all registers are cleared; whenthis pin is driven high, all registers behaveas programmed. This pin is enabled byturning on the Enable device-wide reset(DEV_CLRn) option in the Quartus IIsoftware.DEV_CLRnN/A if option is on. I/O ifoption is off.InputAltera Corporation 6–67August 2005 Configuration Handbook, Volume 1