MC68HC908QB8 Datasheet, PDF (33/236 Pages) Freescale Semiconductor, Inc – To provide the most up-to-date information, the revision of our documents

FLASH Memory (FLASH)
2.6.3 FLASH Mass Erase Operation
Use the following 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.
5. Set the HVEN bit.
6. Wait for a time, t_MErase.
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.
9. Clear the HVEN bit.
10. After time, t_RCV, 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, other unrelated operations may
occur between the steps.
CAUTION
A mass erase will erase the internal oscillator trim value at $FFC0.
2.6.4 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 2-4 shows a flowchart of the programming algorithm.
NOTE
Do not program any byte in the FLASH more than once after a successful
erase operation. Reprogramming bits to a byte which is already
programmed is not allowed without first erasing the page in which the byte
resides or mass erasing the entire FLASH memory. Programming without
first erasing may disturb data stored in the FLASH.
1. Set the PGM bit. This configures the memory for program operation and enables the latching of
address and data for programming.
2. Read the FLASH block protect register.
3. Write any data to any FLASH location within the address range desired.
4. Wait for a time, t_NVS.
5. Set the HVEN bit.
1. When in monitor mode, with security sequence failed (see 17.3.2 Security), write to the FLASH block protect register in-
stead of any FLASH address.
MC68HC908QB8 Data Sheet, Rev. 1
Freescale Semiconductor
33