7.5.5 Writing to EEPROM

The DLPA4000 has an EEPROM mainly intended for default settings and factory trimming parameters. Registers 0x30 through 0x35 can freely be used for customer convenience though, to write a serial number or version information for instance. Writing to EEPROM requires a couple of steps. First the EEPROM needs to be unlocked. Unlock the EEPROM by writing 0xBAh to register 0x2E followed by writing 0xBE to the same register. Both writes must be consecutive, that is, there must be no other read or write operation in between sending these two bytes. Once the password has been successfully written, register 0x30h through 0x35h are unlocked and can be write accessed using the regular SPI protocol. They remain unlocked until any byte other than 0xBABE is written to PASSWORD register 0x2E or the part is power cycled. To permanently store the written data in EEPROM write a 1 to register 0x2F, EEPROM_PROGRAM, > 250 ms later followed by writing a 0 to the same register.

To check if the registers are unlocked, read back the PASSWORD register 0x2E. If the data returned is 0x00h, the registers are locked. If the PASSWORD register returns 0x01h, the registers are unlocked.