On Tue, Jul 26, 2011 at 11:25 PM, Gorka Guardiola <pau...@gmail.com> wrote: > On Tue, Jul 26, 2011 at 9:46 PM, erik quanstrom <quans...@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.
