MC68HC908GR16 Datasheet, PDF (40/276 Pages) Motorola, Inc – Microcontrollers

Memory
2.6.1.2 FLASH Page Erase Operation
Use this step-by-step procedure to erase a page (64 bytes) of FLASH memory to read as a 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.
CAUTION
A page erase of the vector page will erase the internal oscillator trim value
at $FFC0.
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 shorter cycle time.
MC68HC908GR16 Data Sheet, Rev. 5.0
40
Freescale Semiconductor