
W9967CF
Publication Release Date: May 1999
- 37 - Revision A4
7.7 Serial EEPROM Interface
The W9967CF 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
Total length of E
2
PROM data to be returned
0x00
2
TL
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
W9967CF 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 W9967CF 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 W9967CF 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 W9967CF does not
respond with an acknowledge but does generate a following stop condition.