IFMT ← xxxxx010 b
ISPCR ← 100xx010b
/* choice byte-programming command */
/* set ISPEN=1 to enable flash change.
set WAIT=010, 60 MC; assumed 10M X’s*/
/* specify the address to be programmed */
IFADRH ← (Address high byte)
IFADRL ← (Address low byte)
IFD ← (byte date to be written into flash)
SCMD ← 46h
/* prepare data source */
/* trig ISP activity */
SCMD ← B9h
(CPU progressing will be hold here)
(CPU continues)
Program a byte into flash
IFMT ← xxxxx001 b
ISPCR ← 100xx010b
/* choice byte-read command */
/* set ISPEN=1 to enable flash change.
set WAIT=010, 11 MC; assumed 10M X’s*/
/* specify the address to be read */
IFADRH ← (Address high byte)
IFADRL ← (Address low byte)
SCMD ← 46h
/* trig ISP activity */
SCMD ← B9h
(CPU progressing will be hold here)
(CPU continues and currently IFD contain the desired data byte )
Read a byte from flash
Booting Program Entrance
The MPC89x54A boots according to the following rule.
If ( HWBS == 0 ) && ( { ISPAS1, ISPAS0} ≠ { 1, 1 })
System will boot from ISP program
else
System will boot from normal AP program
Above rule is adaptive only for power-up procedure, while not software reset.
Switching from ISP program to AP program
The device permits the user normally start running the AP program as soon as the ISP program
has finished updating the flash content. Just program an instruction at the tail of ISP program as
ISPCR ← 001xxxxxb
30
MPC89x54A Data Sheet
MEGAWIN
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