Hi Robin,
> > See doc/EEPROM-structure, and git commit a45ea32b4ffd. I believe the
> > existing code intentionally goes against what AN_121 describes, as
> > written in that doc.
>
> After some investigation, I think there's a misunderstanding.
> Yes, it appears as if 4 bytes after the serial number are reserved. This
> means that the statement in AN121 "Start Address = the address following
> the last byte of SerialNumber string." is wrong.
>
> However, I think there's still 96 bytes of user area since it all adds
> up nicely -- the 4 extra bytes appear to be aken care of arleady in the
> 48 word user area as stated by AN121.
> There are 128 bytes of internal EEPROM in total (AN121).
> The descriptive strings begin at byte 0x1C (=28) in the EEPROMs I have
> at hand (both written with FTProg and ftdi_eeprom).
>
> 28 + 48*2 + 4 = 128
>
> Also I found out about this because I wanted to reproduce an EEPROM
> written originally with FT Prog using ftdi_eeprom. The strings initially
> written by FT Prog (45 characters) turned out to be 1 character (2
> bytes) too long for libftdi's userarea space check (which was 88 bytes =
> 44 words).
>
> With "FT Prog" I can write up to 48 characters which is exactly what
> AN121 states.
> If "FT Prog" (which I assume is based on FTD2XX) doesn't get it right,
> who does?
that argument sounds sane to me.
@Jim, are you ok with that, too?
> > Either way, the _230X is decribed in its datasheet sa having an
> > identical EEPROM structure as the _R, so any patch that treats them
> > differently is probably not correct.
>
> You mean this datasheet:
> http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT230X.pdf
>
> It does not say its EEPROM/MTP layout is identical to type-R chips.
> It does say:
> "The MTP memory on all FT-X devices can be programmed over USB. This
> method is the same as for the EEPROM on other FTDI devices such as the
> FT232R." (p.33)
>
> It does not give any details about the EEPROM/MTP memory layout, not to
> mention about the available user area space.
>
> Perhaps the other chip's user area space checks in libftdi should also
> be reviewed, based on what "FT Prog" or FT_EE_UASize() reports.
may be, yes. OTOH this should only be done if someone
has the hardware at hand to test the changes (like you did).
Cheers,
Thomas
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