Datasheet

FLASH Memory (FLASH)

FLASH Mass Erase Operation

MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1

MOTOROLA FLASH Memory (FLASH) 49

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4.6 FLASH Mass Erase Operation

Use the following procedure to erase the entire FLASH memory to read

as logic 1:

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

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, t

nvs

(minimum 10 µs).

5. Set the HVEN bit.

6. Wait for a time, t

Erase

(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, t

nvh1

(minimum 100 µs).

9. Clear the HVEN bit.

10. After time, t

rcv

(typical 1 µs),

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.

4.7 FLASH Program 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, or $XXE0. Use the

following step-by-step procedure to program a row of FLASH memory

Figure 4-2 shows a flowchart of the programming algorithm.

NOTE: Only bytes which are currently $FF may be programmed.

1. When in monitor mode, with security sequence failed (see 9.5 Security), write to the FLASH

block protect register instead of any FLASH address.