PIC18F242 MICROCHIP [Microchip Technology], PIC18F242 Datasheet - Page 252

• Manufacturer Part Number: PIC18F242
• Description: 28/40-pin High Performance, Enhanced FLASH Microcontrollers with 10-Bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18FXX2
TBLWT
Syntax:
Operands:
Operation:
Status Affected: None
Encoding:
Description:
Words:
Cycles:
DS39564C-page 250
Q Cycle Activity:
operation
Decode
No
Q1
operation
operation
TABLAT)
[ label ]
None
if TBLWT*,
(TABLAT)
TBLPTR - No Change;
if TBLWT*+,
(TABLAT)
(TBLPTR) +1
if TBLWT*-,
(TABLAT)
(TBLPTR) -1
if TBLWT+*,
(TBLPTR) +1
(TABLAT)
This instruction uses the 3 LSbs of the
TBLPTR to determine which of the 8
holding registers the TABLAT data is
written to. The 8 holding registers are
used to program the contents of Pro-
gram Memory (P.M.). See Section 5.0
for information on writing to FLASH
memory.
The TBLPTR (a 21-bit pointer) points
to each byte in the program memory.
TBLPTR has a 2 MBtye 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
(Read
No
No
Q2
0000
TBLPTR[0] = 0: Least Significant
TBLPTR[0] = 1: Most Significant
operation
operation
TBLWT ( *; *+; *-; +*)
Holding Register;
Holding Register;
Holding Register;
Holding Register;
0000
No
No
Q3
TBLPTR;
TBLPTR;
TBLPTR;
Register or Memory)
Byte of Program
Memory Word
Byte of Program
Memory Word
(Write to Holding
0000
operation
operation
No
No
Q4
nn=0 *
11nn
=1 *+
=2 *-
=3 +*
TBLWT
Example1:
Example 2:
Before Instruction
After Instructions (table write completion)
Before Instruction
After Instruction (table write completion)
TABLAT
TBLPTR
HOLDING REGISTER
(0x00A356)
TABLAT
TBLPTR
HOLDING REGISTER
(0x00A356)
TABLAT
TBLPTR
HOLDING REGISTER
(0x01389A)
HOLDING REGISTER
(0x01389B)
TABLAT
TBLPTR
HOLDING REGISTER
(0x01389A)
HOLDING REGISTER
(0x01389B)
Table Write (Continued)
TBLWT
TBLWT
© 2006 Microchip Technology Inc.
*+;
+*;
=
=
=
=
=
=
=
=
=
=
=
=
=
=
0x55
0x00A356
0xFF
0x55
0x00A357
0x55
0x34
0x01389A
0xFF
0xFF
0x34
0x01389B
0xFF
0x34