MC68HC908EY16 Datasheet, PDF (37/278 Pages) Motorola, Inc – Microcontrollers

FLASH Memory (FLASH)
2.6.2 FLASH Page Erase Operation
Use this step-by-step procedure to erase a page (64 bytes) of FLASH memory to read as logic 1:
1. Set the ERASE bit and clear the MASS bit in the FLASH control register.
2. Read the FLASH block protect register.
3. Write any data to any FLASH location within the address range of the block to be erased.
4. Wait for a time, t_NVS (minimum 10 µs).
5. Set the HVEN bit.
6. Wait for a time, t_Erase (minimum 1 ms or 4 ms).
7. Clear the ERASE bit.
8. Wait for a time, t_NVH (minimum 5 µs).
9. Clear the HVEN bit.
10. After time, t_RCV (typical 1 µs), 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.
NOTE
Due to the security feature (see 19.3 Monitor Module (MON)) the last page
of the FLASH (0xFFDC–0xFFFF), which contains the security bytes,
cannot be erased by Page Erase Operation. It can only be erased with the
Mass Erase Operation.
In applications that require more than 1000 program/erase cycles, use the 4 ms page erase specification
to get improved long-term reliability. Any application can use this 4 ms page erase specification. However,
in applications where a FLASH location will be erased and reprogrammed less than 1000 times, and
speed is important, use the 1 ms page erase specification to get a shorter cycle time.
MC68HC908EY16 • MC68HC908EY8 Data Sheet, Rev. 10
Freescale Semiconductor
37