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FvM's avatar
FvM
Icon for Super Contributor rankSuper Contributor
3 years ago

Cyclone 10 GX, different guidelines for connection of unused GXB RX and REFCLK inputs

Hello, I found that connection suggestions for unused transceiver inputs in Quartus .pin file differ from PCG document. PCG suggests individual ground connection of GXB RX pins and either grounding o...
Kshitij_Intel's avatar
Kshitij_Intel
Icon for Frequent Contributor rankFrequent Contributor
3 years ago

Hi,


Can you please share the quartus .pin file suggestion.


Also, for AC-coupled links, the AC-coupling capacitor can be placed anywhere along the channel subject to the protocol or design requirement. PCI Express protocol requires the AC-coupling capacitor to be placed on the transmitter side of the interface that permits adapters to be plugged and unplugged.


Note: Intel® recommends that you create an Intel® Quartus® Prime design, enter your device I/O assignments, and compile the design. The Intel® Quartus® Prime software will check your pin connections according to I/O assignment and placement rules. The rules differ from one device to another based on device density, package, I/O assignments, voltage assignments, and other factors that are not fully described in this document or the device handbook.


Thank you

Kshitij Goel


FvM's avatar
FvM
Icon for Super Contributor rankSuper Contributor
3 years ago
Hello,
I'm specifically asking about unused Transceiver RX and REFCLK pins.
Pinout file is flagging all pins as GXB_GND*.
"GXB_GND*: Unused GXB Receiver or dedicated reference clock pin. This pin must be connected to GXB_GND through a 10k Ohm resistor."

In contrast, pin connection guidelines give different suggestions.
For GXB-RX:
"Connect all unused GXB_RXn pins directly to GND."
For GXB-REFCLK:
"Connect all unused pins either individually to GND or tie all unused pins together through a single 10-kΩ resistor to GND. Ensure that the trace from the pins to the resistor(s) are as
short as possible."

I read the note quote in your post so, that you are suggesting to follow the pinout file. But the connection guidelines seem more detailed and specific.
Therefore I'd rather keep respecting the guideline document.
Best regards,
Frank