On Wed, Jun 25, 2014 at 11:46 PM, Thomas Schmid <[email protected]>
wrote:
>
> On Mon, Jun 23, 2014 at 4:42 PM, Andreas Fritiofson <
> [email protected]> wrote:
>
>>
>>
>> 1. Live with the slow speed and know that it's going to improve some time
>> in the future.
>> 2. Get an ST-Link (like on the ST discovery boards) and live with the
>> fact that you won't have the same level of control (for example, no vector
>> catch).
>> 3. Get a suitable FTDI based adapter and use the SWD patches currently in
>> Gerrit [1] (or wait for them to get merged). This option is speedy, i.e.
>> 700 kByte/s memory R/W. Flash programming speed of course also depends on
>> the flash driver in OpenOCD and the actual flash controller.
>> 4. Maybe the best option (for everyone else at least :)), rewrite the
>> CMSIS-DAP driver yourself, on top of the asynchronous API [2].
>> 5. There's also the possibility to fix/update the JLink, Versaloon or RPi
>> SWD driver [3] that is also depending on the above API changes.
>>
>>
> Thanks for the very insightful reply. 1 and 2 don't seem options for me.
> For 3, any recommendations on a FTDI based adapter that works with those
> changes?
> For 4, how much work do you think this will be? Any guidelines on it? I am
> definitely considering this route, as the CMSIS-DAP devices are becoming
> more and more numerous on so many eval kits.
> I am also looking at option 5, as we have some BBBs that can use the
> BitBang method too.
>
>
I've mostly tested using a JTAG-lock-pick Tiny 2 [1] which is one of the
adapters that have SWD buffer logic built-in. However, using a suitable
adapter [2] or even a simple resistor trick [3], any old FTDI based JTAG
adapter should work. A "high speed" variant is recommended. See the
available config files under interface/ftdi/.
I can't really say how hard it would be to rewrite the CMSIS-DAP driver,
because it's using HIDAPI instead of libusb and I'm not familiar at all
with that.
/Andreas
[1] http://www.distortec.com/
[2] Like https://www.olimex.com/Products/ARM/JTAG/ARM-JTAG-SWD/
[3] http://openocd.zylin.com/#/c/1958/6//COMMIT_MSG,cm
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