FLASH Memory
FLASH Mass Erase Operation
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA FLASH Memory 61
4.6 FLASH Mass Erase Operation
Use this step-by-step 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
register.
2. Read from the FLASH block protect register.
3. Write any data to any FLASH address(2) within the FLASH
memory address range.
4. Wait for a time, tNVS, minimum of 10 µs.
5. Set the HVEN bit.
6. Wait for a time, tMErase, minimum of 4 ms.
7. Clear the ERASE bit.
8. Wait for a time, tNVHL, minimum of 100 µs.
9. Clear the HVEN bit.
10. After a time, tRCV (minimum of 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 the FLASH memory. While these operat io ns
must be performed in the order shown, other unrelat ed o per ations may
occur between the steps.
2. In monitor mode, when security sequence fails (see Section 10. Monitor ROM (MON)), write
to the FLASH block protect register instead of any FLASH address.