Reminder
The EZ-USB core uses the Table 5-6 data for enumeration only if the ReNum bit is zero.
If ReNum=1, enumeration data is supplied by 8051 code.
5.7
Serial EEPROM Present, First Byte is 0xB0
Table 5-7. EEPROM Data Format for “B0” Load
EEPROM
Address
Contents
0
1
2
3
4
5
6
7
0xB0
Vendor ID (VID) L
Vendor ID (VID) H
Product ID (PID) L
Product ID (PID) H
Device ID (DID) L
Device ID (DID) H
Not used
If, at power-on, the EZ-USB core detects an EEPROM connected to its I2C port with the
value 0xB0 at address 0, the EZ-USB core copies the Vendor ID (VID), Product ID (PID),
and Device ID (DID) from the EEPROM (Table 5-7) into internal storage. The EZ-USB
core then supplies these bytes to the host as part of the Get_Descriptor-Device request.
(These six bytes replace only the VID/PID/DID bytes in the default USB device descrip-
tor.) This causes a driver matched to the VID/PID/DID values in the EEPROM, instead of
those in the EZ-USB core, to be loaded into the OS.
After initial enumeration, the driver downloads 8051 code and USB descriptor data into
EZ-USB RAM and starts the 8051. The code then ReNumerates to come on as the fully
custom device.
A recommended EEPROM for this application is the Microchip 24LC00, a small (5-pin
SOT package) inexpensive 16-byte serial EEPROM. A 24LC01 (128 bytes) or 24LC02
(256 bytes) may be substituted for the 24LC00, but as with the 24LC00, only the first
seven bytes are used.
EZ-USB TRM v1.9
Chapter 5. EZ-USB CPU
Page 5-9
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