MC68HC908AS32A Datasheet, PDF (55/280 Pages) Freescale Semiconductor, Inc – Microcontrollers

FLASH Memory (FLASH)
2.9.4 FLASH Mass Erase Operation
Use this step-by-step procedure to erase the entire FLASH memory to read as a 1:
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
A. Programming and erasing of FLASH locations can not be performed by
code being executed from the same FLASH array.
B. While these operations must be performed in the order shown, other
unrelated operations may occur between the steps. However, care must be
taken to ensure that these operations do not access any address within the
FLASH array memory space such as the COP control register at $FFFF.
C. It is highly recommended that interrupts be disabled during
program/erase operations.
2.9.5 FLASH Program Operation
Programming of the FLASH memory is done on a row basis. A row consists of 64 consecutive bytes with
address ranges as follows:
• $XX00 to $XX3F
• $XX40 to $XX7F
• $XX80 to $XXBF
• $XXC0 to $XXFF
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.
NOTE
1. When in monitor mode, with security sequence failed (see 18.3.2 Security), write to the FLASH block protect register in-
stead of any FLASH address.
MC68HC908AS32A Data Sheet, Rev. 2.0
Freescale Semiconductor
55