mc9s08ac32 Freescale Semiconductor, Inc, mc9s08ac32 Datasheet - Page 52

• Manufacturer Part Number: mc9s08ac32
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 4 Memory
shown include overhead for the command state machine and enabling and disabling of program and erase
voltages.
4.4.3
The steps for executing any of the commands are listed below. The FCDIV register must be initialized and
any error flags cleared before beginning command execution. The command execution steps are:
A partial command sequence can be aborted manually by writing a 0 to FCBEF any time after the write to
the memory array and before writing the 1 that clears FCBEF and launches the complete command.
Aborting a command in this way sets the FACCERR access error flag which must be cleared before
starting a new command.
A strictly monitored procedure must be adhered to, or the command will not be accepted. This minimizes
the possibility of any unintended change to the FLASH memory contents. The command complete flag
(FCCF) indicates when a command is complete. The command sequence must be completed by clearing
52
1. Write a data value to an address in the FLASH array. The address and data information from this
2. Write the command code for the desired command to FCMD. The five valid commands are blank
3. Write a 1 to the FCBEF bit in FSTAT to clear FCBEF and launch the command (including its
write is latched into the FLASH interface. This write is a required first step in any command
sequence. For erase and blank check commands, the value of the data is not important. For page
erase commands, the address may be any address in the 512-byte page of FLASH to be erased. For
mass erase and blank check commands, the address can be any address in the FLASH memory.
Whole pages of 512 bytes are the smallest blocks of FLASH that may be erased. In the 60K
version, there are two instances where the size of a block that is accessible to the user is less than
512 bytes: the first page following RAM, and the first page following the high page registers. These
pages are overlapped by the RAM and high page registers, respectively.
check ($05), byte program ($20), burst program ($25), page erase ($40), and mass erase ($41).
The command code is latched into the command buffer.
address and data information).
Program and Erase Command Execution
1
Byte program
Byte program (burst)
Page erase
Mass erase
Do not program any byte in the FLASH more than once after a successful
erase operation. Reprogramming bits in 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.
Excluding start/end overhead
Parameter
Table 4-5. Program and Erase Times
MC9S08AC60 Series Data Sheet, Rev. 2
Cycles of FCLK
NOTE
20,000
4000
9
4
Time if FCLK = 200 kHz
100 ms
20 µs
20 ms
45 µs
1
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