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Subject: Re: [EEPROM branch] "size_check" init value

From: Thomas Jarosch <thomas.jarosch@xxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Fri, 24 Sep 2010 14:43:22 +0200
On Friday, 24. September 2010 14:20:18 Xiaofan Chen wrote:
> Section "EEPROM Programming -->EEPROM Settings -->USB String
> Descriptors" of the help file (chm format) has the following.
> "This allows for the string descriptors that the device will use to be
> changed on the EEPROM.  The maximum number of characters
>  that the string descriptors can take is 48 including the Manufacturer,
> Product Description and Serial Number strings."

Thanks for checking, I'll change the code to limit
the string length to 48 characters in total.

> From what I read using FT_prog dump of a Luminary LM321968
> board (using FT2232D), of the 64 words EEPROM, the first
> 12s word are not for the strings. And the remaining 52 words, I guess
> 4 words are kind of checksum (or spacer or things like that) for the
> three strings and the user area. I will call them "spacer" later.
> So you got 48 words available for the 4 strings.

The "spacer" is the string "descriptor table". The first byte is the string 
length and the next byte is "0x03" for "type: string".

> > AN_121 also mentions the "manufacturer ID" string additionally
> > to the "manufacturer" string. Any idea what that is?
> ftd2xx.h seems to mention it, but I do not see that in the dump.

Hmm, very strange. I think we leave this one out for now.


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