71M6541DSLASHFSLASHG datasheet(35/166 Pages) MAXIM

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71M6541D/F/G and 71M6542F/G Data Sheet

Rev 5

Name

Address

(Hex)

Reset value

(Hex)

Description

Page

T2CON

0xC8

0x00

Polarity for INT2 and INT3

PSW

0xD0

0x00

Program Status Word

WDCON

0xD8

0x00

Baud Rate Control Register (only WDCON[7] bit used)

0xE0

0x00

Accumulator

0xF0

0x00

B Register

Accumulator (ACC, A, SFR 0x E0):

ACC is the accumulator register. Most instructions use the accumulator to hold the operand. The

mnemonics for accumulator-specific instructions refer to accumulator as A, not ACC.

B Register (SFR 0xF0):

The B register is used during multiply and divide instructions. It can also be used as a scratch-pad register

to hold temporary data.

Program Status Word (PSW, SFR 0xD0 ):

This register contains various flags and control bits for the selection of the register banks (see Table 14).

Table 14: PSW Bit Functions (SFR 0xD0)

PSW Bit

Symbol

Function

Carry flag.

Auxiliary Carry flag for BCD operations.

General purpose Flag 0 available for user.

F0 is not to be confused with the F0 flag in the CESTATUS register.

RS1

working register bank:

RS1/RS0

Bank selected

Location

Bank 0

0x00 – 0x07

Bank 1

0x08 – 0x0F

Bank 2

0x10 – 0x17

Bank 3

0x18 – 0x1F

RS0

Overflow flag.

–

User defined flag.

Parity flag, affected by hardware to indicate odd or even number of one bits in

the Accumulator, i.e., even parity.

Stack Pointer (SP, SFR 0x81):

The stack pointer is a 1-byte register initialized to 0x07 after reset. This register is incremented before

PUSH and CALL instructions, causing the stack to begin at location 0x08.

Data Pointer:

The data pointers (DPTR and DPRT1) are 2 bytes wide. The lower part is DPL (SFR 0x82) and DPL1 (SFR

0x84), respectively. The highest is DPH (SFR 0x83) and DPH1 (SFR 0x85), respectively. The data pointers

can be loaded as two registers (e.g., MOV DPL,#data8). They are generally used to access external

code or data space (e.g., MOVC A,@A+DPTR or MOVX A,@DPTR respectively).

Program Counter:

The program counter (PC) is 2 bytes wide and initialized to 0x0000 after reset. This register is incremented

when fetching operation code or when operating on data from program memory.

71M6541D/F/G Datasheet(PDF) 35 Page - Maxim Integrated Products

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