which disables flash-writing authority, set
SWBS
0,
and trigger a software reset. After that, the
system will be reset (not powered-up), and the system will refer to
SWBS
to startup from AP
program entrance. For power-up procedure, the
HWBS
will be referred to decide the program
entrance, but for software reset,
SWBS
will be referred.
Switch to the ISP program from AP program
The device also permits the user program switches directly to the ISP program. Just program an
instruction in the AP program as
ISPCR
←
x11xxxxx
b
which sets
SWBS
1
to direct the device boot from AP program, and trigger a software reset. After
that, the system will be reset (not powered-up), and the system will refer to
SWBS
to startup from
ISP program entrance.
In-Application Program
The In-Application Program feature is designed for user to Read/Write nonvolatile
data flash.
It
may bring great help to store parameters those should be independent of power-up and
power-done action. In other words, the user can store data in
data flash
memory, and after
shutting down the MCU and rebooting the MCU, user still can get the original value which had
stored in.
The user can program the
data flash
according to the same way as ISP program, and gets
deeper understanding related to SFR
IFD, IFADRL, IFADRH, IFMT, SCMD, and ISPCR.
The
data flash
can be programmed by the AP program as well as the ISP program.
The ISP program may program the AP memory and
data flash,
while the AP program may
program the
data flash
but not the ISP memory. If the AP program desires to change the ISP
memory associated with specific address space, the hardware will ignore it.
Note : Even the users do not need ISP space, the OR0[5:4] still needs to be programmed with
{10} if IAP data flash is desired. In other words, the maximum available size in data flash for IAP
operation is 10K bytes.
MEGAWIN
MPC89x51A Data Sheet
31
MEGAWIN [ MEGAWIN TECHNOLOGY CO., LTD ]
