Configuration Handbook - Kamami.pl

Configuring Cyclone FPGAsTable 13–10. Dedicated Cyclone Device Configuration Pins (Part 2 of 3)Pin NameUserModeConfigurationSchemePin TypenSTATUS – All Bidirectionalopen-drainDescriptionThe device drives nSTATUS low immediately afterpower-up and releases it within 5 µs. (When using aconfiguration device, the configuration device holdsnSTATUS low for up to 200 ms.)Status output. If an error occurs during configuration,nSTATUS is pulled low by the target device.Status input. If an external source drives thenSTATUS pin low during configuration or initialization,the target device enters an error state. DrivingnSTATUS low after configuration and initializationdoes not affect the configured device.CONF_DONE – All Bidirectionalopen-drainIf the design uses a configuration device, drivingnSTATUS low causes the configuration device toattempt to configure the FPGA, but since the FPGAignores transitions on nSTATUS in user-mode, theFPGA does not reconfigure. To initiate areconfiguration, nCONFIG must be pulled low. TheOE and nCS pins in the enhanced configurationdevices and EPC2 devices have optional internalprogrammable pull-up resistors. If the design usesinternal pull-up resistors, do not use external 10-kΩpull-up resistors on these pins. This pin uses Schmitttrigger input buffersStatus output. The target device drives theCONF_DONE pin low before and during configuration.Once all configuration data is received without errorand the initialization clock cycle starts, the targetdevice releases CONF_DONE.Status input. After all data is received andCONF_DONE goes high, the target device initializesand enters user mode.Driving CONF_DONE low after configuration andinitialization does not affect the configured device.The OE and nCS pins in the enhanced configurationdevices and EPC2 devices have optional internalprogrammable pull-up resistors. If the design usesinternal pull-up resistors, do not use external 10-kΩpull-up resistors on these pins. This pin uses Schmitttrigger input buffersAltera Corporation 13–47January 2007 Cyclone Device Handbook, Volume 1