Apr 7, 2013

Search JTAG pinouts for PANTECH UM190 modem

On opening the modem is easy to detect a fairly large number of contact pads.

Appearance modem board
Looking closely to them at once can be dropped four of them, the two joined together and the two are connected to “ground”.

Schematically sketched the location of contacts
Turn on the modem we explain the presence of findings ps_hold and or reset. When you tap a contact terminal TEST restarts the modem.

Determining the ps_hold and reset method of "spear"
In this case, the modem reboots when you touch just one output, usually two.

Marked on the paper output resets the modem
You can now soldered to the remaining contacts modem and start auto search.

You can now soldered to the remaining contacts modem and start auto search.
Trying to find pinout when the modem was not successful. Most likely a modem software disables the JTAG interface, so you should try to find pinout before the modem firmware will disable the JTAG.

At the time of withdrawal and the power supply to the modem client program can generate false detection alert pinouts, it is normal in mind the conclusions of the instability of states at the moment when the modem. In this case, false messages look like this:

False pinout at the time of power off
False pinout at the time of power on
The number of false piouts may vary in this case, there were about 4-5.

While the modem continues to load, and at this point is the detection of the correct pinouts, as judged by read by the CPU ID CODE.
Correct pinout defined at boot time the modem

Sketched the location of the findings can be confirmed whether the output device found RTCK or number 1 was assigned to him by default. To do so, resolder SPT Board findings to the modem so that the number corresponding to the output pin TDO was the maximum (in our case it was and is the seventh number of the seven involved findings), and display a contact number for this RTCK was greater than 1.

Correct pinout including contact RTCK
Note the remaining data in the paper. Work to determine the pinouts over.

The final version of pinouts


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