MC68HC908LJ24 Datasheet, PDF (72/464 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
FLASH Memory (FLASH)
4.5 FLASH Page Erase Operation
Use the following procedure to erase a page of FLASH memory. A page
consists of 128 consecutive bytes starting from addresses $xx00 or
$xx80. The 48-byte user interrupt vectors area also forms a page. The
48-byte user interrupt vectors cannot be erased by the page erase
operation because of security reasons. Mass erase is required to erase
this page.
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 (min. 10µs).
5. Set the HVEN bit.
6. Wait for a time, t_erase (1ms).
7. Clear the ERASE bit.
8. Wait for a time, t_nvh (5µs).
9. Clear the HVEN bit.
10. After time, t_rcv (1µs), the memory can be accessed in read mode
again.
NOTE:
Programming and erasing of FLASH locations cannot be performed by
code being executed from the FLASH memory; the code must be
executed from RAM. While these operations must be performed in the
order as shown, but other unrelated operations may occur between the
steps.
Data Sheet
72
MC68HC908LJ24/LK24 — Rev. 2
FLASH Memory (FLASH)
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