Kinetis Flex NVM read just after reset causes a bus error

[mauroansaloni]

Hello everybody. I'm seeking for some suggestions about a weird problem on a MK10dx32

If I read some bytes from the Flash NVM arranged as EEPROM just after being out of reset, either at power up or after a voluntary reset (watch dog) I get a bus error.

This causes a new start of the program that resets again and again.

The phenomenon shows on many boards , not on all , so i think there must be something critical, but not completely wrong.

To stop this evil behavior and being able to read without troubles I placed  a delay of 100msec  before the first read of the NVM EEPROM  

Is it  a workaround or is something that has to be normally done?

A search through the documentation did not bring any light, so I'm asking if someone already experienced a similar thing.

Thanks for any hint or suggestion

Mauro

[Hui_Ma · Accepted solution]

Hi Mauro,

After the chip finished reset sequence, it need to check Flash Configuration Register (FTFL_FCNFG) [EEERDY] bit about if FlexRAM is ready for EEPROM read.

For devices with FlexNVM: This flag indicates if the EEPROM backup data has been copied to the FlexRAM and is therefore available for read access. During the reset sequence, the EEERDY flag will remain cleared while CCIF is clear and will only set if the FlexNVM block is partitioned for EEPROM.

Wish it helps.

Have a great day,
Ma Hui

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[mauroansaloni]

Thank you Hui_Ma !

I was checking the (FTFL_FCNFG) [EEERDY] bit after a write on the EEPROM, and not also when exiting from reset.

Thanks again for your help.

Mauro