
W9967BCF
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7.7 Serial EEPROM Interface
The W9967BCF supports an external 1K (128
×
8) serial E
2
PROM as an optional source for IHV-specific
Vendor ID and Product ID. The external E
2
PROM data, in stead of the default data, will be used when a
high is sampled at SDA pin (pin 49) during a reset operation.
7.7.1 EEPROM Data Structure
The E
2
PROM contains IHV-specific Vendor ID and Product ID as described in Table 7.14.
Table 7.14 EEPROM Data Structure
Address
Field
Size
Value
Description
0x00
2
TL
Total length of E
2
PROM data to be returned
0x02
idVendor
2
Vendor ID
0x04
idProduct
2
Product ID
7.7.2 EEPROM Operations
The external E
2
PROM will be only read right after a reset operation. TL (defined in address 0x00) bytes
of data will be read by using a sequential read operation.
START condition:
A high-to-low transition of SDA with SCL high is a start condition which must
proceed any other command.
STOP condition:
A low-to-high transition of SDA with SCL high is a stop condition which terminates all
communications. After a read sequence, the stop command will place the E
2
PROM in a standby power
mode.
ACKNOWLEDGE:
All addresses and data words are serially transmitted to and from the E
2
PROM in
8-bit words. The E
2
PROM will acknowledge by pulling SDA low after receiving each address. The
W9967BCF will likewise acknowledge by pulling SDA low after receiving each data word. This must
happen during the ninth clock cycle after each word received and after all other devices have freed the
SDA bus.
Refer to Figure 7.4, a sequential read is initiated by the W9967BCF with a start condition followed by a
7-bit data word address (always 0) and a high read bit. The E
2
PROM will respond with an acknowledge
and then serially output 8 data bits. After the W9967BCF receives an 8-bit data word, it responds with
an acknowledge. As long as the E
2
PROM receives an acknowledge, it will continue to increment the
data word address and serially clock out sequential data words. The sequential read operation is
terminated when the memory address limit (TL) is reached and the W9967BCF does not respond with
an acknowledge but does generate a following stop condition.