KW40Z OTAP safety for no battery devices

[lucianfiran]

KW40Z_Connectivity_Software_1.0.1 (KSDK_1.3.0); IAR 7.50;

As OTAP upload can take from 3 to 5 minutes or more to upload new image software to external SPI flash eeprom, and then 16 seconds to actually update MKW30Z flash from SPI - it is possible to have a power down event.

How safe is using the OTAP and bootloader software update in a system tied to direct wall mount power supply ?

What happens if there is a power down event, worst case scenario ?

(in battery systems it is easier to check for battery status before updating)

[jorge_a_vazquez]

Hi Lucian

What happens if there is a power down event, worst case scenario ?

In the case of the external flash, the worst case scenario is that the image is corrupted, but it will never be loaded to the internal flash, so it does't represent a big problem. in the case that you power down in the load to the internal flash, your application will be corrupted, but if you erase your flash, it should recover its normal operation

Hope this information helps you
Have a great day,
Jorge Alcala

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[lucianfiran]

The bootloader will remain unchanged after OTAP programming ?

The bootloader soft should disable the rest pin and/or SWD pins ?

Should some retry be added ?

            /* Erase Flash sector */
            if (FLASH_OK != FLASH_EraseSector(flashAddr))
                gHandleBootError_d();

like

            if (FLASH_OK != FLASH_EraseSector(flashAddr))
                if (FLASH_OK != FLASH_EraseSector(flashAddr))
                    gHandleBootError_d();

The boot switch is contained in gpBootInfo struct.

I think bootloader will retry to write the image until gpBootInfo switches are set.

On the gpBootInfo struct some counter should be added to keep count of how many erases cycles were performed (Cycling endurance minim 10 000 typical 50 000 cycles.) ?

[jorge_a_vazquez]

Hi Lucian

About your questions

The bootloader will remain unchanged after OTAP programming ? Do you mean the OTAP Client?, Yes, it remains as service available.

The bootloader soft should disable the rest pin and/or SWD pins ? No, it is not needed

Should some retry be added ? No, it is not needed

Best Regards

Jorge Alcala

[lucianfiran]

Yes the OTAP client.