Re: [OpenOCD-devel] Latest DAPLink firmware doesn't work with OpenOCD.

[Antonio B. <bor...@gm...>]

On Mon, Nov 4, 2019 at 8:45 PM <kri...@te...> wrote:
>
> Dear OpenOCD developers,
>
> I've bought the SWDAP probe from ARM (see https://github.com/ARMmbed/mbed-HDK-Eagle-Projects/tree/master/DAPLink/Probes/SWDAP , distributed by L-Tek). This probe works fine with OpenOCD. But when I flash the latest DAPLink firmware v0254 onto the probe (see https://github.com/ARMmbed/DAPLink), it doesn't work anymore. Even earlier DAPLink firmware versions v0253 and v0252 make OpenOCD crash.
>
> Please have a look at my StackOverflow question, where I explain all the details:
> https://electronics.stackexchange.com/questions/465577/daplink-firmware-doesnt-operate-with-openocd
>
> You can also have a look at the GitHub issue on DAPLink (but the StackOverflow question goes into more details):
> https://github.com/ARMmbed/DAPLink/issues/665
>
> It's not sure if the problem originates from the DAPLink firmware or from OpenOCD.

Hi Kristof,

thanks for the SWDAP device you have shipped to me. I succeed to make
it working with OpenOCD.

First of all, a critical HW issue, already logged in
https://github.com/ARMmbed/mbed-HDK-Eagle-Projects/issues/1
You need to replace the resistors R9, R11 and R13, otherwise the
interface will not work properly, even with the original cmsis-dap FW
programmed in SWDAP.
Without this change I get errors even with adapter speed at 1 kHz.

Then, with the HW fix, I succeed to run the interface with any FW
version from v0240 to v0254 available in
https://github.com/ARMmbed/DAPLink/releases
I have used as target a STM32F411, and the FW I have flashed is always
the one named
02XX_lpc11u35_lpc824xpresso_0x0000.bin
that seams compatible with the STM32 (there is no specific one for STM32!)
All these FW are either cmsis-dap V1.00 or V1.10

In the same repository there are FW that are instead cmsis-dap v2 !
But only one is available for SWDAP, 0254_lpc11u35__0x0000.bin
Other interfaces support cmsis-dap v2 from earlier FW revision but I
do not have them!

In version 0254 there is also a FW for ST-Link HW
(0254_stm32f103xb__0x0000.bin) but without the bootloader! I have
recompiled it to test also this HW.
It also uses cmsis-dap v2

cmsis-dap v2 is a game changer! Does not use USB HID anymore but USB
bulk! The driver in OpenOCD does not support it!
The cmsis-dap messages seams the same, but the protocol below is different.
I have sniffed the USB communication by pyocd and quickly patched
OpenOCD to behave in the same way. It works fine.
I have just pushed in gerrit a test "work-in-progress" proof-of-concept.
http://openocd.zylin.com/5394
It will require some additional work before being ready for merge, but
it's functional.
Would you mind testing it on your side? (after replacing the
resistors, of course).

Antonio