CY7C68300C, CY7C68301C
CY7C68320C, CY7C68321C
Document 001-05809 Rev. *B Page 34 of 42
Programming the EEPROM
There are three methods of programming the EEPROM:
■ Stand-alone EEPROM programmer
■ Vendor-specific USB commands, listed in Table 12
■ In-system programming (for example, bed-of-nails tester)
Any vendor-specific USB write request to the Serial ROM device
configuration space simultaneously update internal configuration
register values as well. If the I
2
C device is programmed without
vendor specific USB commands, the AT2LP must be synchro-
nously reset (toggle RESET#) before configuration data is
reloaded.
The AT2LP supports a subset of the ’slow mode’ specification
(100 KHz) required for 24LCXXB EEPROM family device
support. Features such as ’Multi-Master,’ ’Clock Synchroni-
zation’ (the SCL pin is output only), ’10-bit addressing,’ and
’CBUS device support’ are not supported. Vendor-specific USB
commands enable the AT2LP to address up to 256 bytes of
EEPROM data.
LOAD_CONFIG_DATA
This request enables writes to the AT2LP’s configuration data
space. The wIndex field specifies the starting address and the
wLength field denotes the data length in bytes.
Legal values for wValue are as follows:
■ 0x0000 Internal Config bytes, address range 0x2 – 0xF
■ 0x0002 External I
2
C memory device
Internal Config byte writes must be constrained to addresses 0x2
through 0xF, as shown in Table 12. Attempts to write outside this
address space result in undefined operation. Internal Config byte
writes only overwrite AT2LP Configuration Byte registers, the
original data source (I
2
C memory device) remains unchanged.
READ_CONFIG_DATA
This USB request enables data retrieval from the data source specified by the wValue field. Data is retrieved beginning at the address
specified by the wIndex field (see Table 12). The wLength field denotes the length in bytes of data requested from the data source.
Legal values for wValue are as follows:
■ 0x0000 Configuration bytes, addresses 0x0 – 0xF only
■ 0x0002 External I
2
C memory device
Illegal values for wValue result in an undefined operation. Attempted reads from an I
2
C memory device when none is connected result
in an undefined operation. Attempts to read configuration bytes with starting addresses greater than 0xF also, result in an undefined
operation.
Table 12. EEPROM-related Vendor-specific Commands
Label bmRequestType bRequest wValue wIndex wLength Data
LOAD_CONFIG_DATA 0x40 0x01 0x0000 30x02 – 0x0F Data Length Configuration
Data
READ_CONFIG_DATA 0xC0 0x02 Data Source Starting Address Data Length Configuration
Data
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