MPC82L54AP 参数 Datasheet PDF下载

RAM

There are 512 bytes RAM built in MPC82x54A.

The user can visit the leading 128-byte RAM via direct addressing instructions, and we name

those RAM as

direct RAM

that occupies address space 00h to 7Fh.

Followed 128-byte RAM can be visited via indirect addressing instructions, and we name

those RAM as

indirect RAM

that occupied address space 80h to

FFh.

There are extra 256 bytes RAM can be visited via

MOVX

@Ri or @DPTR instructions which

are named

external

RAM. When using

MOVX @DPTR,

the content in DPH is ignored. None

of P0 status and P2 status is affected during MOVX instruction.

Nonvolatile Registers:

There are four Nonvolatile Registers named

OR0, OR1, OR2,

and

OR3

individually. They are

designed to configure the MPC82x54A, i.e.,: to decide to use internal RC oscillator or use

crystal oscillator as oscillating source, or to allocate the built-in flash for application program,

application data and In-System-Program code.

Generally, the only way to program those four nonvolatile registers is making use of a popular

NVM writer, such as: Hi-Lo System All-11, Leaper-48 and Megawin-Provided MCU writer. The

user’s program and the ISP program never can change those option registers.

NVM register: OR0

(Option

Register 0):

Bit-7

LVFWP

Bit-6

ENLVR

Bit-5

ISPAS1

Bit-4

ISPAS0

Bit-3

HWBS

Bit-2

Bit-1

Bit-0

LOCK

reserved1

SB

LVFWP: =

Low-Voltage-Flag-Write-Protecting bit.

0:=

inhibit the flash read/write action via ISP/IAP mechanism while the power supply drops

under a specific voltage level. Typically, the voltage threshold is around 3.7V/2.3V (Operate

in the 5V / 3V) for Fosc =12MHz.

1:=

(default)

No inhibition on the flash-writing action.

ENLVR: =Enable-Low-Voltage-Reset

0:=

Clearing the bit will reset the device while the power supply drops under a specific voltage

level. Typically, the voltage threshold is around 3.7V/2.3V (Operate in the 5V / 3V) for

Fosc = 12MHz.

1:=

(default)

Setting the bit implies never reset the device in spite of voltage dropping.

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MPC82x54A Data Sheet

MEGAWIN