The nCASC
pin is used to cascade configuration devices to configure large APEXTM and FLEXTM devices. The nCASC
pin is driven low when the configuration device's internal address counter reaches its maximum value (when the last bit of the configuration data is sent to the APEX or FLEX device). The internal address counter can only be incremented by the DCLK
signal when the nCS
pin is low. If you only use one configuration device, the nCS
pin is pulled high by the CONF_DONE
signal before the device's internal address counter reaches its maximum value. In this case, the nCASC
pin is not driven low.
To tell when configuration is complete, see the conf_done
or init_done
pin of the FLEX or APEX device.
For more information on all configuration signals, refer to the Configuration Handbook. |