MC68908GZ8MFJE Datasheet, PDF(41/314 Page) Freescale Semiconductor, Inc – Microcontrollers

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MC68908GZ8MFJE Datasheet, PDF (41/314 Pages) Freescale Semiconductor, Inc – Microcontrollers

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FLASH Memory (FLASH)

2.6.4 FLASH Mass Erase Operation

Use this step-by-step procedure to erase entire FLASH memory to read as logic 1:

1. Set both the ERASE bit, and the MASS bit in the FLASH control register.

2. Read from the FLASH block protect register.

3. Write any data to any FLASH address(1) within the FLASH memory address range.

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

5. Set the HVEN bit.

6. Wait for a time, tMErase (minimum 4 ms)

7. Clear the ERASE and MASS bits.

NOTE

Mass erase is disabled whenever any block is protected (FLBPR does not

equal $FF).

8. Wait for a time, tNVHL (minimum 100 Î¼s)

9. Clear the HVEN bit.

10. After a 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 FLASH memory. While these operations must be

performed in the order shown, other unrelated operations may occur

between the steps.

2.6.5 FLASH Program/Read Operation

Programming of the FLASH memory is done on a row basis. A row consists of 32 consecutive bytes

starting from addresses $XX00, $XX20, $XX40, $XX60, $XX80, $XXA0, $XXC0, and $XXE0.

During the programming cycle, make sure that all addresses being written to fit within one of the ranges

specified above. Attempts to program addresses in different row ranges in one programming cycle will

fail. Use this step-by-step procedure to program a row of FLASH memory (Figure 2-4 is a flowchart

representation).

NOTE

Only bytes which are currently $FF may be programmed.

1. Set the PGM bit. This configures the memory for program operation and enables the latching of

address and data for programming.

2. Read from the FLASH block protect register.

3. Write any data to any FLASH address within the row address range desired.

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

5. Set the HVEN bit.

6. Wait for a time, tPGS (minimum 5 Î¼s).

7. Write data to the FLASH address to be programmed.

8. Wait for a time, tPROG (minimum 30 Î¼s).

9. Repeat step 7 and 8 until all the bytes within the row are programmed.

1. When in monitor mode, with security sequence failed (see 20.3.2 Security), write to the FLASH block protect register instead

of any FLASH address.

MC68HC908GZ16 â¢ MC68HC908GZ8 Data Sheet, Rev. 4

Freescale Semiconductor

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