PIC18LF1320-I/SOSQTP 查看數據表（PDF） - Microchip Technology

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PIC18LF1320-I/SOSQTP

18/20/28-Pin High-Performance, Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

Microchip Technology 

PIC18F1220/1320

TBLRD

Table Read

Syntax:

Operands:

[ label ] TBLRD ( *; *+; *-; +*)

None

Operation:

if TBLRD *,

(Prog Mem (TBLPTR)) → TABLAT;

TBLPTR – No Change;

if TBLRD *+,

(Prog Mem (TBLPTR)) → TABLAT;

(TBLPTR) + 1 → TBLPTR;

if TBLRD *-,

(Prog Mem (TBLPTR)) → TABLAT;

(TBLPTR) – 1 → TBLPTR;

if TBLRD +*,

(TBLPTR) + 1 → TBLPTR;

(Prog Mem (TBLPTR)) → TABLAT;

Status Affected: None

Encoding:

0000 0000

0000

10nn

nn = 0*

= 1*+

= 2*-

= 3+*

Description:

This instruction is used to read the

contents of Program Memory (P.M.). To

address the program memory, a pointer

called Table Pointer (TBLPTR) is used.

The TBLPTR (a 21-bit pointer) points

to each byte in the program memory.

TBLPTR has a 2-Mbyte address

range.

TBLPTR[0] = 0: Least Significant

Byte of Program

Memory Word

TBLPTR[0] = 1: Most Significant

Byte of Program

Memory Word

The TBLRD instruction can modify the

value of TBLPTR as follows:

• no change

• post-increment

• post-decrement

• pre-increment

Words:

1

Cycles:

2

Q Cycle Activity:

Q1

Q2

Decode

No

operation

No

No operation

operation (Read Program

Memory)

Q3

No

operation

No

operation

Q4

No

operation

No operation

(Write

TABLAT)

TBLRD

Table Read (Continued)

Example 1:

TBLRD *+ ;

Before Instruction

TABLAT

=

TBLPTR

=

MEMORY(0x00A356) =

After Instruction

TABLAT

=

TBLPTR

=

Example 2:

TBLRD +* ;

Before Instruction

TABLAT

=

TBLPTR

=

MEMORY(0x01A357) =

MEMORY(0x01A358) =

After Instruction

TABLAT

=

TBLPTR

=

0x55

0x00A356

0x34

0x34

0x00A357

0xAA

0x01A357

0x12

0x34

0x34

0x01A358

© 2007 Microchip Technology Inc.

DS39605F-page 229

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