PIC18F010T-I/SN View Datasheet(PDF) - Microchip Technology
Part Name
Description
MFG CO.
'PIC18F010T-I/SN' PDF : 176 Pages View PDF
PIC18F010/020
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
operation
No
operation
(Read
Program
Memory)
Q3
No
operation
No
operation
Q4
No
operation
No
operation
(Write
TABLAT)
TBLRD
Table Read (cont’d)
Example 1:
TBLRD *+ ;
Before Instruction
TABLAT
= 0x55
TBLPTR
= 0x00A356
MEMORY(0x00A356) = 0x34
After Instruction
TABLAT
TBLPTR
= 0x34
= 0x00A357
Example 2:
TBLRD +* ;
Before Instruction
TABLAT
= 0xAA
TBLPTR
= 0x01A357
MEMORY(0x01A357) = 0x12
MEMORY(0x01A358) = 0x34
After Instruction
TABLAT
TBLPTR
= 0x34
= 0x01A358
2001 Microchip Technology Inc.
Preliminary
DS41142A-page 135
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