Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

Cyclone III user I/O stay LOW during JTAG configration

Hi,all I found all user I/Os became LOW during JTAG configruation in my situation. The device is Cyclone III 3C35. However, it is said that user I/Os must be tri-stated during JTAG configuration i...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

Thanks to FvM!

In fact, it is not true that ALL user I/O became LOW during JTAG configruation. This is due to my careless. Actually, only the AS configuration pin: ASDO, which is pin 6 of E144 package, became LOW during JTAG configruation. The others configruation pins and regular user I/O pins are tri-stated.

And, there isn't any external hardware which is pulling-down the ASDO pin. This pin is only LOW during JTAG configruation. After configruation, this pin act as a regular user I/O. I don't kown what's wrong with this pin?!

Regards

hustzq