S12ZVCA - bdm connection lost [SOLVED]

[maxdrm]

Hi all,

I'm using an S12ZVCA with Codewarrior 10.7 on a Windows 7 PC and PE Micro USB Multilink Universal BDM interface.

I'm not able to debug my software as the connection is lost very often.

When the problem happens all the memory read from the micro is read as 0xEE and I have to reset the microcontroller using the reset command .

It looks like a connection lost problem or an unexpected reset of the microcontroller.

The things happens in the following way:

 - Start a debug session

 - Start the microcontoller

 - Pause the microcontroller after a while.

Sometime, after a few seconds, the microcontroller restart by itself and the connection is lost.

Anyone experienced similar problems? Any idea what could be the problem?

Thank You, everyone

Max

[iggi · Accepted solution]

Hi Max,

Not easy to tell what is the cause of the issue. Some answers can help to move on:

Do you use NXP development board or is it your custom made? Do you have another one to try?

Does the Pemicro programmer works when programming other micro i.e. board?

It would be good to know if the HW part is faulty or not.

You ca try and program the micro, disconnect the bdm, press reset and let MCU run. This will let you know if the programmer and MCU are OK. For example, a program that switches a LED on and off continuously.

But, now i think you are having a problem with COP watchdog. Do you use COP watchdog? Do you write any value to CPUCOP register?

Regards,

iggi

[maxdrm]

Hi iggi, thank You for your answer.

1. Do you use NXP development board or is it your custom made? Do you have another one to try?
   The board is custom, I've got ten boards and the problem is the same for each board. Nevertheless they are prototypes, thus something could be wrong anyway. 
2. Does the Pemicro programmer works when programming other micro i.e. board?
   The Pemicro programmer should works correctly, as my collegue is able to use it with a S12G equipped board.
3. It would be good to know if the HW part is faulty or not. You can try and program the micro, disconnect the bdm, press reset and let MCU run. This will let you know if the programmer and MCU are OK. For example, a program that switches a LED on and off continuously.
   The board seems to work correctly: the software behave as is expected to do, both when running with debugger or when running standalone disconnected by BDM. 
4. But, now i think you are having a problem with COP watchdog. Do you use COP watchdog? Do you write any value to CPUCOP register?
   Yes, I'm using the watchdog. I expected the watchdog were stopped in BDM mode, instead you have to set the bit RSBCK in CPMUCOP register in order  to stop "COP and RTI Stop in Active BDM Mode". In my sw the bit was cleared.
   Now, with the bit set, it seems to works correctly. Thank You iggi!

Yet I don't understand why the COP were not resetting the microcontroller immediately when activating the BDM mode. Perhaps it was made by the debugger software?

Regards

Max