PIC18F2420 MICROCHIP [Microchip Technology], PIC18F2420 Datasheet - Page 308

• Manufacturer Part Number: PIC18F2420
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F2420/2520/4420/4520
TBLWT
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
DS39631A-page 306
if TBLWT*,
(TABLAT)
TBLPTR – No Change;
if TBLWT*+,
(TABLAT)
(TBLPTR) + 1
if TBLWT*-,
(TABLAT)
(TBLPTR) – 1
if TBLWT+*,
(TBLPTR) + 1
(TABLAT)
None
This instruction uses the 3 LSBs of
TBLPTR to determine which of the
8 holding registers the TABLAT is written
to. The holding registers are used to
program the contents of Program
Memory (P.M.). (Refer to Section 6.0
“Flash Program Memory” for additional
details on programming Flash memory.)
The TBLPTR (a 21-bit pointer) points to
each byte in the program memory.
TBLPTR has a 2-MByte address range.
The LSb of the TBLPTR selects which
byte of the program memory location to
access.
The TBLWT instruction can modify the
value of TBLPTR as follows:
• no change
• post-increment
• post-decrement
• pre-increment
1
2
Table Write
TBLWT ( *; *+; *-; +*)
None
operation
Decode
0000
Q1
No
TBLPTR[0] = 0: Least Significant
TBLPTR[0] = 1: Most Significant
operation
operation
TABLAT)
(Read
0000
Holding Register;
Holding Register;
Holding Register;
Holding Register;
Q2
No
No
TBLPTR;
TBLPTR;
TBLPTR;
operation
operation
0000
Byte of Program
Memory Word
Byte of Program
Memory Word
Q3
No
No
nn=0 *
Register )
operation
operation
(Write to
Holding
=1 *+
=2 *-
=3 +*
11nn
Q4
No
No
Preliminary
TBLWT
Example1:
Example 2:
Before Instruction
After Instructions (table write completion)
Before Instruction
After Instruction (table write completion)
TABLAT
TBLPTR
HOLDING REGISTER
TABLAT
TBLPTR
HOLDING REGISTER
TABLAT
TBLPTR
HOLDING REGISTER
HOLDING REGISTER
TABLAT
TBLPTR
HOLDING REGISTER
HOLDING REGISTER
(00A356h)
(00A356h)
(01389Ah)
(01389Bh)
(01389Ah)
(01389Bh)
Table Write (Continued)
TBLWT *+;
TBLWT +*;
 2004 Microchip Technology Inc.
=
=
=
=
=
=
=
=
=
=
=
=
=
=
55h
00A356h
FFh
55h
00A357h
55h
34h
01389Ah
FFh
FFh
34h
01389Bh
FFh
34h