MC9S08QD4 Datasheet, PDF (41/202 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 4 Memory Map and Register Definition
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 obeyed or the command will not be accepted. This minimizes the
possibility of any unintended changes to the flash memory contents. The command complete flag (FCCF)
indicates when a command is complete. The command sequence must be completed by clearing FCBEF
to launch the command. Figure 4-2 is a flowchart for executing all of the commands except for burst
programming. The FCDIV register must be initialized following any reset before using any flash
commands.
START
0
FACCERR ?
CLEAR ERROR
WRITE TO FCDIV⁽¹⁾
(1) _{Required only once}
after reset.
WRITE TO FLASH
TO BUFFER ADDRESS AND DATA
WRITE COMMAND TO FCMD
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF ⁽²⁾
(2) _{Wait at least four bus cycles before}
checking FCBEF or FCCF.
FPVIO OR
FACCERR ?
NO
YES
ERROR EXIT
0
FCCF ?
1
DONE
Figure 4-2. Flash Program and Erase Flowchart
4.5.4 Burst Program Execution
The burst program command is used to program sequential bytes of data in less time than would be
required using the standard program command. This is possible because the high voltage to the flash array
does not need to be disabled between program operations. Ordinarily, when a program or erase command
is issued, an internal charge pump associated with the flash memory must be enabled to supply high
voltage to the array. Upon completion of the command, the charge pump is turned off. When a burst
MC9S08QD4 Series MCU Data Sheet, Rev. 3
Freescale Semiconductor
41