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

Andy Green andy at
Mon Apr 28 10:31:19 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| 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 :-)
|> but it would be far simpler if we can communicate with the GSM chip
|> UART fully internally somehow
| 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.

No problem then, I got the idea before it was the way to get firmware in
there, but there is evidently another way.

|> 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

We discussed this last week: MSP430 is not in OpenOCD and I at least
have doubts about what will happen if we have multiple things on the
scanchain on the software side.  Allen is also dubious about wiring up
multi-device chain on first prototype.

By fixing JTAG to only be for CPU, we have lowest risk for issues on
that side, and by using UART on MSP430 we can leverage the second UART
channel on FTDI to reach and program that too.

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


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

Sure, to the extent we can influence that kind of physical production
detail we should suggest his idea again.

- -Andy
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