[USRP-users] Ethernet over SFP+ in custom FPGA design (X3x0)

Christian Lenz christian.lenz at freedelity.com
Tue Nov 28 15:09:43 EST 2017

Ian and Sugandha,

thank you very much for your comments and also for the attached file.
Sadly, another three questions remain for the moment:
1. In the attached file, there is a series of 48? bits named "Ettus  
Padding". Is this an Ettus specific bit sequence and where can I find  
information on this?
2. If powering up and programming the FPGA, the clock from the PLL is  
not present because it must be programmed over SPI first. According to  
the HDL source files and pin constraints, the corresponding SPI master  
module in the FPGA is clocked  from a 125MHz clock. I assume this  
clock to be present without any configuration, is this true?
3. Do you know where to find the missing pages of the X3xx schematics  
document (13-17)? I would assume to find the 125MHz clock source on  
page 17.

Thanks a lot!

Zitat von Ian Buckley <ianb at ianbuckley.net>:

> Christian,
> CHDR packets are encapsulated in UDP/IP between Host and USRP. See  
> the attachment.
> PHY+ MAC functionality live under the x300_sfpp_io_core. However  
> these blocks do not encapsulate/decapsulate the network packets.
> All the ethernet/IP/UDP framing fields are added by chdr_eth_framer  
> on egress, and will be removed on ingress by etc_dispatch (if needed).
> -Ian

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