WP34s flash technical erase procedure

[MarkHaysHarris777]

(02-01-2015 09:52 PM)Marcus von Cube Wrote:  

(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.

Thanks for the explanation, Marcus; and thanks for all you have done with this project-- very nice work.

I am nervous, because I know that every time I update my 34s, I first have to kill it! :-}

I plan to mod the unit with crystal and caps this week, and then another 'erase' flash cycle! Thanks again for everything/ The WP34s is quickly becoming my favorite calculator ever. Its faster than the 50g, its more fun than the 35s, and it leaves my TI units in the dust.

Mit freundlichen Grüßen

marcus