MC68HC908GZ8 Datasheet, PDF (127/344 Pages) Motorola, Inc – Microcontrollers

FLASH Memory (FLASH)
FLASH Page Erase Operation
11.4 FLASH Page Erase Operation
Use this step-by-step procedure to erase a page (64 bytes) of FLASH memory to
read as logic 1. A page consists of 64 consecutive bytes starting from addresses
$XX00, $XX40, $XX80, or $XXC0. The 44-byte user interrupt vectors area also
forms a page. Any FLASH memory page can be erased alone.
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 address within the page address range
desired.
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 a time, t_RCV (typical 1 µs), the memory can be accessed again in read
mode.
NOTE:
Programming and erasing of FLASH locations cannot be performed by code being
executed from FLASH memory. While these operations must be performed in the
order shown, other unrelated operations may occur between the steps.
NOTE: It is highly recommended that interrupts be disabled during program/ erase
operations.
NOTE:
In applications that need 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 lower minimum erase
time.
MC68HC908GZ8
Freescale Semiconductor
FLASH Memory (FLASH)
Data Sheet
127