VSBC-6862
Rev 1.43
96
6.5. Chip select
Before accessing a internal peripheral, the corresponding chip select must be initialized.
The description of all chip select initializations are described in the Software description.
It's important to note the order in which OR0 and BR0 are programmed. When coming out of reset and
CS0 is the global chip select, OR0 MUST be programmed AFTER BR0. In all other cases BRx would
be programmed after ORx.
Note that for SDRAM, some registers are to be programmed in addition to the chip select. These
registers initialization are described in the corresponding chapter.
6.6. Serial EEPROM
The VSBC-6862 provides one on-board serial EEPROM on the I
2
C bus which handle most of the
configuration attributes.
General Information Format
Field
Offset
Size
Values
Magic Cookie
$00
8
$41 $43 $54 $49 $53 $00 $00 $00 ("ACTIS")
Size of EEPROM
$08
2
$01 $00
Reserved
$0A
4
$00 $00 $00 $00
Date
$0E
2
YY MM (BCD Format)
Options $10
240
max XX
Options may be fixed length or variable length. All options begin with a tag octet, which uniquely
identifies the option (values 128 to 254 are reserved for user). Fixed-length options without data
consist of only a tag octet. Only options 0 and 255 are fixed length. All other options are variable-
length with a length octet following the tag octet. The value of the length octet does not include the two
octets specifying the tag and length. The length octet is followed by "length" octets of data. In the case
of some variable-length options the length field is a constant but must still be specified.
Pad Option
The pad option can be used to cause subsequent fields to align on word boundaries.
The code for the pad option is 0, and its length is 1 octet.
E.g.:
$00
End Option
The end option marks the end of valid information in the vendor field. Subsequent octets
should be filled with pad options.
The code for the end option is 255, and its length is 1 octet.
E.g.:
$FF
Product Identifier Option (optional)
This option specifies the name of the product (ASCII terminated by a zero byte).
The code for this option is 1, and its minimum length is 1.
E.g.: $01 $0E 'V' 'S' 'B' 'C' '-' '6' '8' '6' '2' '/' '0' '0' '0' $00
Factory Identifier Option (optional)
This option specifies the name of the product in factory (ASCII terminated by a zero byte).
The code for this option is 2, and its minimum length is 1.
E.g.: $02 $02 '?' $00
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