Knowledge Base Article

Do the Active Serial configuration pins always have weak pull-up resistors in Cyclone® V devices?

Description

No.  In Cyclone® V devices, the Active Serial (AS) pins DCLK, AS_DATA0, AS_DATA1, AS_DATA2, AS_DATA3 and nCSO have 25 kOhm pull-up resistors enabled only when the MSEL pins are set to AS configuration scheme.  In Intel® Quartus® Prime Software Standard Edition version 18.1 and earlier, the fitter report incorrectly says these pins have weak pull-up resistors regardless of the configuration scheme in Device and Pin Options.  The Cyclone V Device Handbook: Volume 1: Device Interfaces and Integration version 2019.01.16 or earlier doesn't mention pull-up resistors on these pins.

Resolution

Ignore  the fitter report which says these pins have weak pull-up resistors when AS configuration scheme is not chosen in Intel Quartus Prime software. 

The Cyclone V Device Handbook: Volume 1: Device Interfaces and Integration has been updated and mentions that these pins have 25 kOhm pull-up resistors when the MSEL pins are set to AS configuration scheme.

Updated 3 months ago
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