W99681CF Datasheet, PDF (37/78 Pages) Winbond – JPEG USB Dual Mode Camera Chip

W99681CF
7.7 Serial EEPROM Interface
The W99681CF supports an external 1K (128×8) serial E²PROM as an optional source for IHV-specific
Vendor ID and Product ID. The external E²PROM 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 E²PROM contains IHV-specific Vendor ID and Product ID as described in Table 7.14.
Table 7.14 EEPROM Data Structure
Address Field
Size
0x00
2
0x02 idVendor
2
0x04 idProduct
2
Value
TL
Description
Total length of E²PROM data to be returned
Vendor ID
Product ID
7.7.2 EEPROM Operations
The external E²PROM 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 E²PROM in a standby power
mode.
ACKNOWLEDGE: All addresses and data words are serially transmitted to and from the E²PROM in
8-bit words. The E²PROM will acknowledge by pulling SDA low after receiving each address. The
W99681CF 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 W99681CF with a start condition followed by a
7-bit data word address (always 0) and a high read bit. The E²PROM will respond with an acknowledge
and then serially output 8 data bits. After the W99681CF receives an 8-bit data word, it responds with
an acknowledge. As long as the E²PROM 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 W99681CF does not respond with
an acknowledge but does generate a following stop condition.
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Publication Release Date: March 2000
Revision A1