MC68HC908AT32 Datasheet, PDF (53/378 Pages) Freescale Semiconductor, Inc – Microcontrollers

FLASH Erase Operation
4.5 FLASH Erase Operation
Use the following procedure to erase a block of FLASH memory:
1. Set the ERASE bit and the BLK0 and BLK1 bits in the FLASH control register. See Table 4-2 for
block sizes.
2. Read from the block protect register: address $FF80.
3. Write to any FLASH address with any data within the block address range desired.
4. Set the HVEN bit.
5. Wait for a time, t_Erase.
6. Clear the HVEN bit.
7. Wait for a time, t _Kill for the high voltages to dissipate.
8. Clear the ERASE bit.
9. After time, t_HVD, the memory can be accessed in read mode again.
NOTE
While these operations must be performed in the order shown, other
unrelated operations may occur between the steps.
Table 4-2 shows the various block sizes which can be erased in one erase operation.
Table 4-2. Erase Block Sizes
BLK1
0
0
1
1
BLK0
0
1
0
1
Block Size, Addresses Cared
Full array: 32 Kbytes (A15)
One-half array: 16 Kbytes (A15 and A14)
Eight rows: 512 Bytes (A15–A9)
Single row: 64 Bytes (A15–A6)
In step 2 of the erase operation, the cared addresses are latched and used to determine the location of
the block to be erased. For the full array, the only requirement is that A15 be high. Writing to any address
in the range $8000 to $FFFF will enable the full-array erase.
MC68HC908AT32 Data Sheet, Rev. 3.1
Freescale Semiconductor
53