STC12LE5616AD datasheet(88/377 Pages) STC

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5.3 Instruction Definitions

ACALL addr 11

Function:

Absolute Call

Description:

ACALL unconditionally calls a subroutine located at the indicated address.The instruction

increments the PC twice to obtain the address of the following instruction, then pushes the

16-bit result onto the stack (low-order byte first) and increments the Stack Pointer twice.

The destination address is obtained by suceesively concatenating the five high-order bits of

the incremented PC opcode bits 7-5,and the second byte of the instruction. The subroutine

called must therefore start within the same 2K block of the program memory as the first

byte of the instruction following ACALL. No flags are affected.

Example:

Initially SP equals 07H. The label “SUBRTN” is at program memory location 0345H. After

executingthe instruction,

ACALL SUBRTN

at location 0123H, SP will contain 09H, internal RAM locations 08H and 09H will contain

25H and 01H, respectively, and the PC will contain 0345H.

Bytes:

Cycles:

Encoding:

a10 a9 a8 1

0 0 1 0

a7 a6 a5 a4

a3 a2 a1 a0

Operation:

ACALL

(PC)← (PC)+ 2

← (PC)+ 2

(PC)+ 2

(SP)←(SP) + 1

←(SP)+1

(SP) + 1

((sP)) ← (PC

← (PC

(PC

7-0)

(SP)←(SP) + 1

←(SP)+1

(SP) + 1

((SP))←(PC

←(PC

(PC

15-8)

(PC

10-0)← page address

← page address

page address

ADD A,<src-byte>

Function:

Add

Description:

ADD adds the byte variable indicated to the Accumulator, leaving the result in the

Accumulator. The carry and auxiliary-carry flags are set, respectively, if there is a carry-

out from bit 7 or bit 3, and cleared otherwise. When adding unsigned integers, the carry flag

indicates an overflow occured.

OV is set if there is a carry-out of bit 6 but not out of bit 7, or a carry-out of bit 7 but not bit

6; otherwise OV is cleared. When adding signed integers, OV indicates a negative number

produced as the sum of two positive operands, or a positive sum from two negative operands.

Four source operand addressing modes are allowed: register,direct register-indirect, or

immediate.

Example:

The Accumulator holds 0C3H(11000011B) and register 0 holds 0AAH (10101010B). The

instruction,

ADD A,R0

will leave 6DH (01101101B) in the Accumulator with the AC flag cleared and both the carry

flag and OV set to 1.

STC12LE5616AD Datasheet(PDF) 88 Page - STCmicro Technology Co,.Ltd

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