PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 318

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18FXX8
TBLWT
Syntax:
Operands:
Operation:
Status Affected: None
Encoding:
Description:
DS41159B-page 316
Table Write
[ 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
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
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 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
0000
TBLPTR[0] = 0: Least Significant
TBLPTR[0] = 1: Most Significant
TBLWT ( *; *+; *-; +*)
Holding Register;
Holding Register;
Holding Register;
0000
Holding Register;
TBLPTR;
TBLPTR;
TBLPTR;
Byte of Program
Memory Word
Byte of Program
Memory Word
0000
nn=0 *
11nn
=1 *+
=2 *-
=3 +*
TBLWT Table Write (Continued)
Words: 1
Cycles: 2
Q Cycle Activity:
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)
operation
Decode
Q1
No
TBLWT
TBLWT
operation
operation
TABLAT)
(Read
Q2
No
No
2002 Microchip Technology Inc.
*+;
+*;
=
=
=
=
=
=
=
=
=
=
=
=
=
=
operation
operation
0x55
0x00A356
0xFF
0x55
0x00A357
0x55
0x34
0x01389A
0xFF
0xFF
0x34
0x01389B
0xFF
0x34
Q3
No
No
Register )
operation
operation
(Write to
Holding
Q4
No
No