MC68HC908GT16_07 Datasheet, PDF (42/292 Pages) Freescale Semiconductor, Inc – Microcontrollers

Memory
1. Set the ERASE bit and clear the MASS bit in the Flash control register.
2. Read the Flash block protect register.
3. Write any data to any Flash location within the address range of the block to be erased.
4. Wait for a time, t_NVS (minimum 10 μs).
5. Set the HVEN bit.
6. Wait for a time, t_Erase (minimum 1 ms or 4 ms).
7. Clear the ERASE bit.
8. Wait for a time, t_NVH (minimum 5 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 as shown, but other unrelated operations may occur
between the steps.
CAUTION
A page erase of the vector page will erase the internal oscillator trim values
at $FF80 and $FF81.
In applications that require more than 1000 program/erase cycles, use the 4 ms page erase specification
to get improved long-term reliability. Any application can use this 4 ms page erase specification. However,
in applications where a Flash location will be erased and reprogrammed less than 1000 times, and speed
is important, use the 1 ms page erase specification to get a shorter cycle time.
2.6.4 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 (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
1. When in monitor mode, with security sequence failed (see 19.3.2 Security), write to the Flash block protect register instead
of any Flash address.
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
42
Freescale Semiconductor