TLF35584 - SPI Write to Protected Registers

[#1]

Hello,

I want to change the register values (WDCFG0) of the TLF35584VS1. They are protected against being overwritten accidently. Therefore I sent a dedicated 32 Bit UNLOCK sequence via SPI: 0x8756, 0x87DE, 0x86AD and 0x8625.
I checked the status of the protection by reading the register PROTSTAT, I send 0x5000 on MOSI and received 0x8001 on MISO. That means the access to write protected registers is still locked.

So how can I get access to protected registers?

[#2]

I have SPI communication to this SBC working.
I write these data to the SBC:

Unlock:
0x8756
0x87DE
0x86AD
0x8625

Disable watchdog and error pin:
0x8D27
0x8A01

Lock:
0x87BE
0x8668
0x877D
0x8795

After this I can read PROTSTAT register and it gives me 0xF0, i.e. all 4 keys are valid and unlocked.

[#3]

Hi Felix, get a copy of the application note AP32342 Testing and servicing the TLF35584.