On Sun, 8 Dec 2002, Matthew Dharm wrote:

> BCD is nybble-oriented, not byte oriented.  Look at the example you quoted:
> 2.10 is 0x0210, not 0x020a (as your suggestion would have it).

As I quoted, the format is OxJJMN, JJ is the major, M the minor and N the
sub version. In that example 0x0210, JJ=0x02, M=0x1, N=0x0, which is 2.10.

The USB specification makes distinction between minor and sub versions,
which might imply an packed BCD format (two BCD numbers in one byte).
Also, 0xa isn't a valid BCD number, only 0x0 to 0x9 are.

This document -
http://www.usb.org/developers/data/devclass/ccsVersioning1_0.pdf - Section
5.1 states:

Offset  Field                   Size    Value   Description

2       bcdFeatureVersion       2       BCD     A BCD value that encodes
                                                the revision of the CSS
                                                Feature as 4 BCD digits
                                                where the decimal point is
                                                between the 2nd and 3rd
                                                digits.

The provided example (0x0210) is misleading...


Rui Saraiva



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