GTA04 USB OVP, USB charger detect, USB-OTG & 6400, earjack DL_GSM, JTAG

Joerg Reisenweber joerg at
Mon Apr 28 11:51:31 CEST 2008

Werner Almesberger schrieb:
> Andy Green wrote:
>> I don't know what all the constraints were for making that external jack
>> method in the first place,
> I have yet to see a good reason for it :-)

Maybe flash new GSM-FW at POS or remote service? Dunno... Anyway we're
all happy once we get rid of it.

>> but it would be far simpler if we can communicate with the GSM chip
>> UART fully internally somehow

I think there is a ting called FLUID for the Calypso. No idea what
Siemens or whoever is doing but I think it's quite usual to flash via
whatever serial IF we got on GSM-module.

> Way too sophisticated :-) There's exactly one time in the life of the
> phone when this interface is used, and that's during calibration at
> the factory. We can use test points on the PCB and a fixture with the
> corresponding pogo pins.

Exactly my suggestion a few hours ago, which was pretty appreciated by
Tim Lee and Allen Chang

>> We should not connect JTAG to MSP430 and just have JTAG on CPU.  We can
>> program the MSP430 using a UART connection.
> Hmm, I'm curious what made you change your mind on that. To me this
> looks like we're planting a big fat wart on a previously beautiful
> solution. I guess Milosch must have told you something scary ... :-(

Yup, what's this now? JTAG was the main beauty of 430, no?
Only question for me was how the JTAG-software is supposed to be
configured to handle the particular serial daisychain.
(And not to incidentally blow the fuse of 430 btw XD )

>> Well we can make a debug connector how we like for the prototype,

That's what it's all abut if I got this right: the prototype, to test
the 'new' JTAG circuitry and have a fallback option.
I suggested a 4pin mini-jumper thing for this purpose. You could jumper
it to chain 6400 and 430, and you could access each of them with an
individual debug board, as proposed by Allen.
BTW: mustn't forget to have separate clock and rst then as well. :-o

>>... but
>> what we need is the FTDI chip on there with USB connection of its own to
>> drive the CPU JTAG and provide console.
> Yup. I don't think we want to invent any new debug connector. If
> there's anything else we need, we're better off if this goes to
> test points and then a fixture.

Just for he cnvenience of our sw-engineers who are going to use this
thing as a evaluation board eventually, I think we have to find at least
one method to do flash and JTAG, that's not involving a fixture.

> We should develop these fixtures (Milosch's design that can be
> easily produced in small series) in parallel to the main PCB.


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