FS91M68

Rev. 1.3

16/24

11. Instruction Set

The FS91M68 instruction set consists of 36 instructions. Each instruction is a 16-bit word with an

OPCODE and one or more operands. The detail descriptions are below.

Note: FS91M68 does not have HALT instruction to avoid the system error occurrence when fast

releasing and plugging-in the battery repeatedly.

Instruction Set Summary

Table 11-1： FS91M68 Instruction Set

Instruction

Operation

Cycle=Fsys/4

Flag

ADDLW k

[W]

← [W] + k

1

C, DC, Z

ADDPCW

[PC]

← [PC] + 1 + [W]

2

None

ADDWF f, d

[Destination]

← [f] + [W]

1

C, DC, Z

ADDWFC f, d

[Destination]

← [f] + [W] + C

1

C, DC, Z

ANDLW k

[W]

← [W] AND k

1

Z

ANDWF f, d

[Destination]

← [W] AND [f]

1

Z

BCF f, b

[f<b>]

← 0

1

None

BSF f, b

[f<b>]

← 1

1

None

BTFSC f, b

Skip if [f<b>] = 0

1, 2

None

BTFSS f, b

Skip if [f<b>] = 1

1, 2

None

CALL k

Push PC + 1 and GOTO k

2

None

CLRF f

[f]

← 0

1

Z

CLRWDT

Clear watch dog timer

1

None

COMF f, d

[f]

← NOT([f])

1

Z

DECF f, d

[Destination]

← [f] -1

1

Z

DECFSZ f, d

[Destination]

← [f] -1, skip if the result is zero

1, 2

None

GOTO k

PC

← k

2

None

INCF f, d

[Destination]

← [f] +1

1

Z

INCFSZ f, d

[Destination]

← [f] + 1, skip if the result is zero

1, 2

None

IORLW k

[W]

← [W] | k

1

Z

IORWF f, d

[Destination]

← [W] | [f]

1

Z

MOVFW f

[W]

← [f]

1

None

MOVLW k

[W]

← k

1

None

MOVWF f

[f]

← [W]

1

None

NOP

No operation

1

None

RETFIE

Pop PC and GIE = 1

2

None

RETLW k

RETURN and W = k

2

None

RETURN

Pop PC

2

None

RLF f, d

[Destination<n+1>]

← [f<n>]

1

C,Z

RRF f, d

[Destination<n-1>]

← [f<n>]

1

C, Z

SLEEP

Stop OSC

1

PD

SUBLW k

[W]

← k – [W]

1

C, DC, Z

SUBWF f, d

[Destination]

← [f] – [W]

1

C, DC, Z

SUBWFC f, d

[Destination]

← [f] – [W] –C

1

C, DC, Z

XORLW k

[W]

← [W] XOR k

1

Z

XORWF f, d

[Destination]

← [W] XOR [f]

1

Z

Note：

f：memory address (00h ~ 7Fh).

w：work register.

k：literal field, constant data or label.

d：destination select: d=0 store result in W,

d=1: store result in memory address f.

b：bit select (0~7).

[f]：the content of memory address f.

PC：program counter.

C：Carry flag

DC：Digit carry flag

Z：Zero flag

TO：watchdog time out flag

WDT：watchdog timer counter