Enumeration of EZ-USB® FX2LP™ from Off-Chip Memory - KBA92900

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    Version: **

     

    Question: How do you make FX2LP™ (128-pin package) enumerate from off-chip memory?

     

    Answer:

    The EZ-USB® executes the code from off-chip memory only under the following three conditions:

    •   A flash, EEPROM, or other memory is attached to the address/data bus.
    •   The EEPROM connected to I2C lines does not have a valid first byte (0xC0 or 0xC2).
    •   The EA pin of FX2LP is connected to logic high.

    Note: If the connected off-chip memory does not have firmware, then it will not enumerate as the default device.

    Figure 1. EA Pin Connected to Logic High