Before today JTAG (Joint Test Action Group) pinouts for Topaz were completely unknown, but today the-equinoxe was able to discover them. This is a serial bus with four signals: Test Clock (TCK), Test Mode Select (TMS), Test Data Input (TDI), and Test Data Output (TDO). The bus is used as a test bus for the ‘Boundary-Scan’ of ICs, as in Design-For-Testability.
Originally posted by the-equinoxe
I purchased a drowned HTC Diamond 2 which I used to house my MDA V in.
Now I was in possession of a broken mainboard.
Since the JTAG pinouts are unknown till this date, I stripped the mainboard from all its components and traced the board in order to find the JTAG.
Had to make new probes from some needles in order to trace from the BGA-Grid..
The difficulty here was that the test-pins where on the other side as where the MPM 7200-A was, and with those tiny bga-vias it was real hard to trace.
Some pictures of the board (before stripping)
The front side of the Mainboard (it is a single board device, apart from speakers, LCD and antenna no further external parts, all on one board!).
The Pins I traced:
These should suffice to JTAG the device.