ICE40 based USB E1 adapter
unrelated to the SAM4S based E1 adapter approach of #2484 and #3272, tnt has been working on a FPGA based E1 interface. For more details, see his OsmoDevCon 2019 Presentation
There's currently a prototype board that contains the analog frontend (transformer, biasing) which attaches to an ICE40 evaluation board. Both the E1 and USB soft cores are working in principle, but are not yet fully interoperating. The full chain is expecte to work pretty soon.
The current source can be found in
I'm creating this ticket to track the status here on osmocom.org. I'll create sub-tasks for related issues.