Freescale Semiconductor MC68HC908MR32 - Manual (Page 40)

Memory
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
40 Freescale Semiconductor
2.8.3 FLASH Mass Erase Operation
Use this step-by-step procedure to erase the entire FLASH memory.
1. Set both the ERASE bit and the MASS bit in the FLASH control register.
2. Read 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
MErase
(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
NVHL
(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 shown, other unrelated operations may
occur between the steps.
1. When in monitor mode, with security sequence failed (see 18.3.2 Security ), write to the FLASH block protect register instead
of any FLASH address.