CDR3 Flash (UC3F) EEPROM
MPC561/MPC563 Reference Manual, Rev. 1.2
21-20
Freescale Semiconductor
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.
21.3.2
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.
21.3.3
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
,” for more information on
disabling the UC3F EEPROM
•
While the UC3F EEPROM is in STOP mode—See
Section 21.3.9, “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 21.3.3.1, “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.
NOTE
After setting/clearing UC3FCTL[HSUS], reset, programming writes, erase
interlock write, setting EHV, clearing SES or setting/clearing SIE, the page
buffers may not contain valid information. The UC3F forces an off-page
read before an on-page read can be accomplished to ensure data coherency.
For information regarding how the two read page buffers in the UC3F EEPROM are associated to array
blocks, refer to
Section 21.2.2, “UC3F EEPROM Array Addressing
The UC3F module is configured as a page mode memory. The UC3F module uses an internal address
comparator to monitor incoming addresses to determine if the addressed information is stored in a read
page buffer. When the address comparator determines that the requested information is not stored in a read
page buffer, an array off-page read operation retrieves 32 bytes of data from the Flash array and transfers
the addressed data to the data bus.
In the MPC563, the UC3F module contains two 32-byte read page buffers. In the module, one buffer is
dedicated to the most recently accessed instruction fetches and the other read page buffer is dedicated to
the most recently loaded data access.
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...