MC68HC908QY4CDW Datasheet, PDF(34/184 Page) Freescale Semiconductor, Inc

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MC68HC908QY4CDW Datasheet, PDF (34/184 Pages) Freescale Semiconductor, Inc – Microcontrollers

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Memory

ERASE â Erase Control Bit

This read/write bit configures the memory for erase operation. ERASE is interlocked with the PGM bit

such that both bits cannot be equal to 1 or set to 1 at the same time.

1 = Erase operation selected

0 = Erase operation unselected

PGM â Program Control Bit

This read/write bit configures the memory for program operation. PGM is interlocked with the ERASE

bit such that both bits cannot be equal to 1 or set to 1 at the same time.

1 = Program operation selected

0 = Program operation unselected

2.6.2 FLASH Page Erase Operation

Use the following procedure to erase a page of FLASH memory. A page consists of 64 consecutive bytes

starting from addresses $XX00, $XX40, $XX80, or $XXC0. The 48-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 location within the address range of the block to be erased.

4. Wait for a time, tNVS (minimum 10 Î¼s).

5. Set the HVEN bit.

6. Wait for a time, tErase (minimum 1 ms or 4 ms).

7. Clear the ERASE bit.

8. Wait for a time, tNVH (minimum 5 Î¼s).

9. Clear the HVEN bit.

10. After time, tRCV (typical 1 Î¼s), 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. While these operations

must be performed in the order as shown, but other unrelated operations

may occur between the steps.

CAUTION

A page erase of the vector page will erase the internal oscillator trim values

at $FFC0 and $FFC1.

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.

MC68HC908QY/QT Family Data Sheet, Rev. 6

Freescale Semiconductor

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