Memory
6. Clear the ERASE bit.
7. Wait for a time, t (5 µs).
nvh
8. Clear the HVEN bit.
9. After time, t (1 µs), the memory can be accessed in read mode again.
rcv
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.
2.5.4 FLASH Mass Erase Operation
Use the following procedure to erase the entire FLASH memory:
1. Set both the ERASE bit and the MASS bit in the FLASH control register.
2. Write any data to any FLASH location within the FLASH memory address range.
3. Wait for a time, t
(5 µs).
nvs
4. Set the HVEN bit.
5. Wait for a time t (200 ms). (See NOTE below.)
me
6. Clear the ERASE bit.
7. Wait for a time, t
(100 µs).
nvh1
8. Clear the HVEN bit.
9. After time, t (1 µs), the memory can be accessed in read mode again.
rcv
NOTE
Due to the relatively long mass erase time, user should take care in the
code to prevent a COP reset from happening while the HVEN bit is set.
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.
2.5.5 FLASH Program Operation
Programming of the FLASH memory is done on a row basis. A row consists of 64 consecutive bytes
starting from addresses $XX00, $XX40, $XX80 or $XXC0. Use the following procedure to program a row
of FLASH memory. (Figure 2-4 shows a flowchart of the programming algorithm.)
1. Set the PGM bit. This configures the memory for program operation and enables the latching of
address and data for programming.
2. Write any data to any FLASH location within the address range of the row to be programmed.
3. Wait for a time, t
(5 µs).
nvs
4. Set the HVEN bit.
5. Wait for a time, t
(10 µs).
pgs
6. Write data to the FLASH location to be programmed.
7. Wait for time, t (20 µs to 40 µs).
prog
8. Repeat steps 6 and 7 until all bytes within the row are programmed.
9. Clear the PGM bit.
MC68HC908AP Family Data Sheet, Rev. 4
44
Freescale Semiconductor
FREESCALE [ Freescale ]
