On Sun, Oct 13, 2019 at 1:28 AM alejandro.estay@gmail.com wrote:
Hi I’ve seen an EHCI debug dongle in the old wiki. I’m trying to build one for 2 purposes: debug a homebrew os/Shell and make it a new UEFI bootloader. However I don’t know where to find further documentation or comments about this. I also dont’ know what is the current or most up to date schematic to build the “sandwich” and what tracks cut and what not. I have bought those blue cypress FX2LP boards and I don’t know how to check revisions. Also, I’dont know exactly what software can be used to control it. It would be desirable if one can send stop or install some breakpoints with Visual studio’s debugger or WinDBG or GDB or something like that. thanks in advance for your advice.
Hi
I created the original FX2LP dongle sandwich, crafting together pieces from different fx2lib sources back in 2013. I think my repository regressed (no longer built) already in 2014-2015 after some sdcc update and I never had interest to maintain that; coreboot devs had switched to USB gadgets like BBB screwdriver and dual-FT232H.
There was further work [1] linked in wiki that claims to work as a compatible net20dc replacement with windows kernel debugger. I never built or run that firmware. I may still have the hardware somewhere but I don't remember them having any distinct PCB revision silkscreens printed, you just need to trace the pins. The FX2LP boards I had were actually relabeled FX2, which might also may break net20dc compatibility.
I would go with one of the other non-FX2LP approaches instead:
- use pre-built beaglebone black screwdriver image, route USB gadget (g_dbpg) to TCP (how to make it appear as virtual COM port for WinDBG I have no clue of) - some phone or devboard with USB OTG 2.0 operating in device mode, otherwise same as above - in case you develop with some TianoCore / EDK, which claims net20dc support, make it compatible with FT232H, it should be just a matter of sending couple different USB packets [2]
[1] https://github.com/night199uk/fx2lib/pull/2 [2] https://review.coreboot.org/c/coreboot/+/10063
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