Input to XADC with BKO Card

Question

Hi there,

I have a MicroZed 7020 Board and want to read VN/VP values. Vor my IO Ports Vivado lets me only choose Package Pin L10 and K9.

Ok, so I look into the HW Guide (http://microzed.org/sites/default/files/documentations/MicroZed_HW_UG_v1_4.pdf) and on page 17 it tells me I reach those pins through JX1 97 and 99..

So I switch to the BKO Schematics (http://zedboard.org/sites/default/files/documentations/MBCC-BKO_RevA_Schematic_131114.pdf) to find out what pins its going to be on my breakout board. I would assume I connect my input signal to whatever pins are connected to JX1 97 and 99.

but that document says JX 97 and 99 are tied to ground? Besides I cant reach 99 from the BKO Board.

What am I missing here?

What pins on the breakout board do I have to put my input signal on?

thanks!

trillian · Accepted Answer

Hi Josh,

you are right, the BKO HW User Guide states that one can use Bank 35 IO pins. In order to use these, you have to configure the XADC to use Xaux pins. I tried that and it works (not in my design yet but I can see my signal on the xadc monitor)

however, I was talking about the "Dedicated Package Pins" from Bank 0 as described on Page 15 from the XADC Reference Manual https://www.xilinx.com/support/documentation/user_guides/ug480_7Series_XADC.pdf

So for anybody who finds this with the same question I know now for certain: It does make a difference if I choose the dedicated or auxiliary analog channels. UG480 Page 30 for example states: For the dedicated channel (VP/VN), the minimum acquisition time (bipolar mode) required is 3 ns while it is 300 ns for any auxiliary channel.

But anyways, it is clear to me now that I have to use Vaux as long as I'm working with the BKO Board. Thanks!