I can unsecure the MCU(S12 and secured) with usb multilink, but I can't erase flash data?

[daviddai]

Hi,

I use HI-WAVE and USB BDM Multilink to debug my MM912H634,

Step1: I unsecure the MCU, passed.

Step2: I click HC12Multilink->Flash...

then warning as below,

"Error while loading diagnostics to target system.

The chip may be secured, or the derivative selected be wrong."

So I can't access to the flash to erase it.

Any reason?

Thanks a lot!

Best Regards

David dai

[RadekS · Accepted solution]

Hi David,

Unfortunately there isn’t any feedback after unsecure script whether it procedure was executed successfully or not.

Typical issue:

MM912H634 contains analog and MCU dies.

We have to ensure that analog die will not interrupt our communication by watchdog reset.

Therefore we have to connect 7V-10V voltage at TCLK pin for disabling watchdog at analog die.

If you use KIT912H634EVME Evaluation Board, please set J7 jumper into position 1-2.

If you use KIT912H634EVME Evaluation Board and USB BDM Multilink, you should also disconnect TBDML interface from BKGD and REST pin by disconnecting JP14, JP15 jumpers. Otherwise TBDML interface could interact with external BDM interface.

For complete mass erase by BDM device (in special mode) you can use also unsecure12 tool from P&E:

http://www.pemicro.com/downloads/download_file.cfm?download_id=16

Unsecure_12 Help Files:

http://www.pemicro.com/downloads/download_file.cfm?download_id=14

Note: For downloading is necessary registration.

I hope it helps you.

Have a great day,
RadekS

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EDIT: fixed range for Watchdog Disable Voltage.

[daviddai]

Hello RadekS,

Thanks for your response.

I already sovled this issue.

I disconnected REST and REST_A and connect REST to BDM directly,

then everyting is ok, I can unsecure and flash MCU right.

I think the root cause is kind of what you said.

Thanks!

Best Regards

David dai