WP34s flash technical erase procedure

[Marcus von Cube]

(01-28-2015 03:02 AM)MarkHaysHarris777 Wrote:  I have a question (am confused) about the the erase procedure. Does the erase strobe actually erase anything?

Yes, ERASE is ERASE! With the original HP firmware running there is no way to clear the boot bit GPNVM1 which controls whether the flash memory or the built-in boot ROM takes control of the chip on power on. ERASE does two things: It clears the boot bit and erases the flash memory.

Once WP 34S firmware is loaded there is a second way to clear the boot bit: ON+D followed by ON+S+S. This leaves the flash memory intact and allows for the preservation of the backup RAM image stored in flash while updating the firmware.

Once the boot bit is cleared there is only one way to set it again to recover the flash contents: Use the original SAM-BA software by Atmel to set the bit. This only makes sense if there is a valid flash image left. After an ERASE this is definitely gone.

In any case you will lose the contents of RAM.