Question: After correctly enumerating for a number of times, an FX2LP device all of a sudden comes up as "Cypress FX2LP - EEPROM Missing". Why does this happen?
Answer: The I2C EEPROM interfaced to the FX2LP chips is vulnerable to data corruption during device power up and power down. If the first data byte is corrupted, a c2 load can no longer happen from the EEPROM. Hence, no firmware is downloaded to the onchip RAM of FX2LP and it enumerates with the default VID/PID of 04B4/8613. To protect the EEPROM from possible data corruption during power up and power down, a few precautions can be taken. Application Note AN5078 describes in detail the design guidelines for assuring the data integrity of serial EEPROM devices when used in FX2LP designs.
