Motorola MPC533 Reference Manual page 841

electrically erasable and programmable non-volatile memory for embedded application in
microcontrollers.
19.3.1 Reset
The device signals a reset to the UC3F EEPROM by asserting the reset signal. A reset is
the highest priority operation for the UC3F EEPROM and terminates all other operations.
The UC3F EEPROM module uses reset to initialize register bits to their default reset value.
If the UC3F EEPROM is in program or erase operation (UC3FCTL[EHV] = 1 and
UC3FCTL[SES] = 1) and a reset is issued, the module will perform the needed interlocks
to disable the high voltage without damage to the high voltage circuits. Reset terminates
any other mode of operation and forces the UC3F EEPROM module to a state ready to
receive accesses.
During power up and power down periods, it is assumed that the reset signal is asserted to
prevent accidental program/erase disturb of the UC3F array.
19.3.2 Register Read and Write Operation
The UC3F EEPROM control registers are accessible for read or write operation at all times
while the device is powered up and enabled except during reset.
19.3.3 Array Read Operation
The UC3F EEPROM array is available for a read operation under most conditions while
the device is powered up. Reads of the array are not allowed in the following instances:
• During reset—When in information or cleared censorship with ACCESS = 0
• While the UC3F EEPROM is disabled—See Section 19.3.10, "Disabled," for more
information on disabling the UC3F EEPROM
• While the UC3F EEPROM is in STOP mode—See Section 19.3.9, "Stop
Operation," for more information on STOP mode
• While high voltage is applied to the array during program and erase
operation —HVS = 1 or EHV = 1 and not suspended
The address of an incoming read access is compared to the address for which data is
currently held in the read page buffers. If the data corresponding to the read address is
currently held in one of the two read page buffers, the data is fetched from the appropriate
read page buffer. A data fetch from a read page buffer is an on-page read operation
Section 19.3.3.1, "Array On-Page Read Operation." If the data is not contained in one of
the read page buffers, 32 bytes of information is fetched from the UC3F array, and the
addressed data is driven onto the data bus. A data fetch from the UC3F array is an off-page
read operation.
MOTOROLA
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Chapter 19. CDR3 Flash (UC3F) EEPROM
UC3F Operation
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