Motorola MPC533 Reference Manual page 836

Programming Model
Table 19-5. UC3FCTL Bit Descriptions (continued)
Bits Name
31 EHV Enable high voltage. EHV can be asserted only after the SES bit has been asserted and a valid
programming write(s) or erase hardware interlock write has occurred. If an attempt is made to
assert EHV when SES is negated, or if a valid programming write or erase hardware interlock
write has not occurred since SES was asserted, EHV will remain negated.
The external program or erase enable pin (EPEE) and EHV are used to control the application
of the program or erase voltage to the UC3F EEPROM module. High voltage operations to the
UC3F EEPROM array, special shadow locations or FLASH NVM registers can occur only if
EHV = 1 and EPEE = 1.
Only after the correct hardware and software interlocks have been applied to the UC3F
EEPROM can EHV be set. Once EHV is set, SES cannot be changed and attempts to read the
array will not be acknowledged.
Clearing EHV during a program or erase operation will safely terminate the high voltage
operation. If EHV is cleared while using the embedded hardware program/erase algorithm, the
program/erase routine will abort the operation and exit normally.
0 Program or erase pulse disabled
1 Program or erase pulse enabled
SES
EHV
HVS
PEGOOD
19.2.2 UC3F EEPROM Array Addressing
The UC3F array is divided into eight blocks, 64 Kbytes in size, which may be
independently erased. Two blocks are host to a 16-Kbyte small block.
Seventeen bits of address are used to decode locations in the UC3F array. The read control
logic in the UC3F EEPROM module decodes the upper 14 bits of that address to determine
if the desired data is currently stored in one of the two read page buffers. If the data is
already present in one of the two read page buffers, a read operation is not completed to the
UC3F array core, and 64 bits of data are transferred from the appropriate read page buffer
to the BIU. This type of array read access is an on-page read.
In the event that the read control logic determines that the desired data is not contained
within one of the read page buffers, a read access to the UC3F array core is completed and
32 bytes of data are transferred from the array core. Only the addressed 64 bits of data will
be transferred to the BIU. This type of array read access is an off-page read. The BIU
19-14
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
PEGOOD
Valid Time
Figure 19-4. PEGOOD Valid Time
MPC533 Reference Manual
Description
PEGOOD
Valid Time
MOTOROLA