Precautions when using as user I/O pins

Even if the nCONFIG, nSTARUS, CONF_DONE pins are used as user I/O pins, these pins aretreated as configuration pins during configuration (including initialization), so one of the following actions is required.

★ Tri-state external I/O drivers and drive external weak pull-up resistors. ^(*)
* If removing the external weak pull-up resistor, Intel recommends removing it after the device enters user mode.

or

★ Use an external I/O driver to drive the pin to the same state as an external weak pull-up resistor.

again,
★ When using configuration pins as user I/O pins,

Only the nCONFIG pin must be used as a single-ended input pin ^*.
* If assigned as an output pin or bidirectional pin, a compilation error will occur.

If you set Enable nCONFIG, nSTATUS, and CONF_DONE pins = Off but none of the nCONFIG, nSTATUS, and CONF_DONE pins are used as user I/O, then the unused pins are handled similarly to regular user I/O. Assign attributes in the Reserved Pin option.

At that time, the nCONFIG pin must be an input attribute (As input ~).

The nSTATUS and CONF_DONE pins can have any attribute.

In that case, please perform the processing on the board appropriately according to the setting contents.

[Related Information] Quartus Prime Getting Started Guide - Pin Assignment Method

Note that when Enable nCONFIG, nSTATUS, and CONF_DONE pins = Off, these pins become GPIOs during user mode. Please note that you will not be able to reconfigure using

Hanako's Tweet

Based on the above, in my personal opinion, it is still recommended to use the configuration pins as dedicated pins.

 

Observe these when using configuration pins as user I/O pins in user mode.