Programmable Devices
CPLDs, FPGAs, SoC FPGAs, Configuration, and Transceivers
21610 Discussions

nSTATUS and CONF_DONE in user-mode

Altera_Forum
Honored Contributor II
2,286 Views

Can I toggle nSTATUS and/or CONF_DONE configuration signals after PS-configuration in user-mode?

0 Kudos
7 Replies
Altera_Forum
Honored Contributor II
1,060 Views

no, they are both dedicated configuration pins (on CIII at least)

0 Kudos
Altera_Forum
Honored Contributor II
1,060 Views

What will be, if nSTATUS and/or CONF_DONE is pulled down after configuration (in user mode)?

0 Kudos
Altera_Forum
Honored Contributor II
1,060 Views

i think i misunderstood your original question, the FPGA cannot drive nSTATUS or CONF_DONE, but your PS controller should control the signals according to the configuration chapter of the device handbook

0 Kudos
Altera_Forum
Honored Contributor II
1,060 Views

In handbook nothing said about this: What will be, if nSTATUS and/or CONF_DONE is pulled down after configuration (in user mode)?

0 Kudos
Altera_Forum
Honored Contributor II
1,060 Views

 

--- Quote Start ---  

In handbook nothing said about this 

--- Quote End ---  

 

It's mentioned in the configuration handbook under device configuration pins.: Driving the pins low for a configured device is ignored.
0 Kudos
Altera_Forum
Honored Contributor II
1,060 Views

Thank You! 

 

For CycloneIII on pg. 595 of “config_handbook.pdf” (Table 9–22): 

--- 

Driving nSTATUS low after configuration and initialization does not affect the configured device. …device ignores transitions on nSTATUS in user mode… 

 

After all configuration data is received without error and the initialization cycle starts, the target device releases CONF_DONE. Driving CONF_DONE low after configuration and initialization does not affect the configured device. 

--- 

 

But for nCE: “However, all user IO pins will be held in tri-state whilst nCE is pulled high during user mode.” (Solution ID: rd01102011_672)
0 Kudos
Altera_Forum
Honored Contributor II
1,060 Views

 

--- Quote Start ---  

However, all user IO pins will be held in tri-state whilst nCE is pulled high during user mode. 

--- Quote End ---  

 

The statement can't be found in regular Altera documents, and at least isn't correct for all devices. I guess, it's simply erroneous. nCE is e.g. used to enable external access to a connected AS flash. You won't want other pins than the AS connected pins tristated in this case, and as far as I experienced, they aren't.
0 Kudos
Reply