Tools: Quartus® II
Device: Cyclone® V
Category: Device (I/O)


To use the Cyclone V device's nCEO pin as a configuration pin, you must compile with Quartus II with the following settings:

Assignments menu ⇒ Device ⇒ Device and Pin Options... ⇒ General ⇒ Check Enable nCEO output

The default setting is unchecked, so it can be used as a user I/O pin.

Note that this pin is used as a configuration pin in multi-device configuration when connecting to the nCEO pin of the previous device and the nCE pin of the following device with a 10 KΩ pullup on VCCPGM. .

Please refer to the device handbook for details.
 https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/cyclone-v/cv_5v2.pdf
* Search with the keyword "Multi-Device Configuration".