PIC18F6525_13 Datasheet, PDF (313/400 Pages) Microchip Technology – 64/80-Pin High-Performance, 64-Kbyte Enhanced Flash Microcontrollers with A/D

PIC18F6525/6621/8525/8621
TBLRD
Table Read
Syntax:
[ label ] TBLRD ( *; *+; *-; +*)
Operands:
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
 2003-2013 Microchip Technology Inc.
DS39612C-page 313