Re: [9fans] jtag programmers

[Gorka Guardiola <paurea@gmail.com>]

On Tue, Jul 26, 2011 at 11:25 PM, Gorka Guardiola <paurea@gmail.com> wrote:
> On Tue, Jul 26, 2011 at 9:46 PM, erik quanstrom <quanstro@quanstro.net> wrote:
>> can someone point me at a list of plan9 usb/serial compatable
>> jtag programmers?
>>
>
> As far as I know, ft2232 chips and their variants may work, but I have only
> tried it with the Sheeva plug.
>
> The ft2232 serial chip inside the sheeva
> can drive all sorts of serial things, including input to a jtag state machine
> if connected properly. Inside the sheeva plug (and some other arm boards),
> the chip is actually connected to the jtag input of the SOC inside it,
> but you need
> the concret details on how this is done for what you are using.
>
> What I do is I program (this is what usb/serial does) the interface connected to
> the jtag for the right configuration to drive it. The device is also
> programmable
> and you need to program it (it is done so that the latency of the USB does not
> kill you). Then you need to communicate with the other side, which includes
> driving the reset bits (which depend on the concrete electronics connecting the
> serial chip to the jtag interface) and then sending the right commands.

All this is done outside usb/serial. Only a couple of parameters (latency and
bit mode) are configured in usb/serial and a file is served.

G.