Re: [OpenOCD-user] SWD via FTDI

[Paul F. <fer...@gm...>]

Hi,

On Fri, Aug 08, 2014 at 09:58:02AM +0100, Tim Hutt wrote:
> That chip has 4 bit-bang pins (CBUS0-3). See page 13 of the data sheet:
> [1]http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf
> Here's the application note describing how to use it (with FTDI's proprietary
> driver): [2]https://strawberry-linux.com/pub/AN232R-01_FT232RBitBangModes.pdf
> It seems like it might be a newer bit-banging mode which isn't supported by
> OpenOCD? 

That's a limited mode (the chip doesn't have an MPSSE engine) that was
never supported by the OpenOCD officially.

If you grab implementation from here:
http://vak.ru/doku.php/proj/bitbang/bitbang-jtag , port it to the
generic bitbanging API (+ http://openocd.zylin.com/#/c/2004/ ) in
OpenOCD, and contribute it upstream, you'll get SWD support
there. Alternatively, you can add SWD support in there (to his syncbb
implementation, it's buffered so should be faster than plain
bitbanging) just as was recently done with ftdi, vsllink and jlink
drivers (see git log).

> I have some experience of reverse engineering USB protocols, so I could
> potentially add support for this mode if it is needed, but I need a bit more
> guidance about how to integrate it into OpenOCD.

Having FT232R support upstream might be beneficial, please just ask if
you stumble on something in OpenOCD.

TIA
-- 
Be free, use free (http://www.gnu.org/philosophy/free-sw.html) software!
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