[USRP-users] Hardware clocks, X310

Jason Matusiak jason at gardettoengineering.com
Thu Feb 28 11:37:52 EST 2019

Cherif.  I will attempt to take a stab at a few of your questions.  Don't take my answers as 100% right....

1 - All the blocks run at the same rate, but I am pretty sure you can implement an MMCM within your block to lower the rate for your needs and then back up to the crossbar rate.  Don't quote me, but I feel like I had this conversation with someone a few years back on the mailing list.
2 - The ADC/DAC are tied to the master clock rate (in the case of the X310, either 186.32MHz, or 200MHz)
3 - I don't believe so unless you do what I mentioned in the first comment.

All that said, I believe a lot of stuff can be tweaked under the hood, but it is hard to say what that will break, and it isn't exactly supported.

From: USRP-users <usrp-users-bounces at lists.ettus.com> on behalf of Cherif Diouf via USRP-users <usrp-users at lists.ettus.com>
Sent: Thursday, February 28, 2019 10:05 AM
To: usrp-users at lists.ettus.com
Subject: [USRP-users] Hardware clocks, X310

Hello guys,

I am a researcher working with the X310 USRP. I have a couple of questions regarding the Hardware clocks.

The bus_clock and radio_clk are by default respectively set at 166 MHz and 200 MHz.

And if I am right the crossbar clock ce_clk is also at 200 MHz. Is there a solution to bring it down to ce_clk = 50 MHz, in that case

1)      Does it mean that all the Kintex XC410T blocks will run at 50 MHz ? Is this safe?

2)       What about the ADC and DAC and their sampling clock?

3)      Finally can we have different RFnoc blocks running at different clock frequencies and still have the  crossbar  running at a given clock frequency?

Best Regards

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