Re: [9fans] jtag programmers

[Bruce Ellis <bruce.ellis@gmail.com>]

I've got a bucket full of jtag stuff that some dildo hasn't paid for
so I guess I can give it away. You'll have to wait 'til I get back to
Sydney tho. Warning! J-tag cables are much beliked by fluffy doggie.

brucee

On Wed, Jul 27, 2011 at 2:58 AM, Gorka Guardiola <paurea@gmail.com> wrote:
> 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.
>
>