If I do a read entire chip (as it happens just after erasing a sector of flash) using J-flash the returned data implies there is no memory at the address (0x80000) - or I assume it does as it shows "--" for its value. If I go to the IAR debugger it shows FF. Now I am more inclined to believe the J-flash SW but would rather the IAR is right (as it would mean the erase sector call worked).

Sequence is:-
1) run jflash - using STR912_Bootbank1.jflash
2) I select device str912FAW47 Bootbank 1 in the J-link task bar (is there a way of making that sticky please as I seem to need to redo it for each time I run J-flash?)
3) Erase chip (ok, I know I'm being a bit paranoid)
it does occasionally throw up an error at this point but just selecting erase chip again works the 2nd time. If useful this is the error
Erasing chip ...
- Erasing 40 sectors, 2 ranges, 0x0 - 0x1FFFF, 0x200000 - 0x3FFFFF
- ERROR: Write memory error @ address 0x50000000, word access: Memory access timeout.
- ERROR: RAM check failed @ address 0x50000000.
- ERROR: Write: 0x03020100 07060504
- ERROR: Read: 0xAAAAAAAA AAAAAAAA
- ERROR: (0 bytes of RAM have been checked successfully)
- ERROR: Failed to erase chip

4) Fill with zero
5) read back entire chip (at this point the memory @ 0x80000 is shown as "--" in J-flash)
6) Hit Ctrl-D in IAR and Dl my app - following your previous suggestion that also has no flash loader except the one in the J-link taskbar app. (at this point IAR shows the image at both 0 and 0x80000 according to IAR mem view but still "--" in J-flash [later: I think this duplicatation only happens when I have used J-flash prior to IAR])
7) run to my code that erases a sector and somehow the memory @ 0x80000 is now 0 according to IAR (which is what it should be) but still "--" in J-flash
run past the code that erases a sector and IAR correctly shows it as FF - J-flash still on "--"

Sorry there's a lot in there but wanted to give as much hopefully useful data as poss (also quite a few Qus)

BTW I'm not sure if specifying the device via the taskbar is nec. for J-flash (behaviour is the same if I don't) but thought I'd do it to cover that base

Yes boot bank set to be 1.
My turn to say you didn't read what I said The address I'm looking at is 0x80000 (4 zeros) as I am trying to write to bank 0 ... which should be there.

Any thoughts pls?

Ta very much! You're absolutely right and it explains an awful lot.


I have no idea where I got the 0x80000 from - at least I have been consistent:-} I have been working based on that for a while and I was sure I'd checked it before I contacted you originally.

[Later] Ah I see it now. It came from the AN2675 ST document which gives (sort of) guidelines on how to write a boot loader. At least I'm not going totally daft.

Danke vielmals!!!

I can't say everything is working on my bootloader yet but as far as the original Q is concerned, yes that explains what I was seeing so it can be closed.