Baking a Magician to discover its JTAG pins

1. grab the datasheet

PXA272x

2. locate the following signal pins:

  • nTRST (Test Rest
  • TDI (Test Data Input)
  • TDO (Tet Data Output)
  • TMS (Test Mode Select)
  • TCK (Test Clock)

4. find those on the circuit board

5. heat your oven 🙂

6. get the chip off the board

my first try wasn’t too successful

so here we go again

7. now trace the previously identified pins

8. mission accomplished:

9. Resources

Wallaby JTAG, iPAQ 3600 JTAG

10. Notes

I think it is possible to do this without killing the device (which in my case didn’t matter because I got an already dead one just for this task).

Therefore you should prebake the circuit board at around 100°C for some time (to get the rid of the moisture) and only use the minimal temperature to unsolder the parts you want to remove/replace.

Also it might be a good idea to fixate the board so you dont accidentially move components once the solder is liquid (like I did – of course 🙂 ).

Don’t hesitate to contact me in case you need some more traces, or parts of this board (though I can’t guarantee nothing)

3 Gedanken zu „Baking a Magician to discover its JTAG pins“

  1. Great work! It would be great if you still have that board. Could you find where pins from any of the UART interfaces are going to? Could you test contacts near the miniUSB socket(think it’s there)?
    Another interesting thing is to determine where the second usb HOST is connected to.
    I will appreciate very much any information. Some refound via paypal for you work is also possible.

  2. Hey imperfect,

    Unfortunately I gave that board away more than a year ago – I asked that internetfriend if he could trace said things for you … if he does I will get back to you.

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