PIC18F2455-I/SP Microchip Technology Inc., PIC18F2455-I/SP Datasheet - Page 251

• Manufacturer Part Number: PIC18F2455-I/SP
• Description: Microcontroller; 24 KB Flash; 2048 RAM; 256 EEPROM; 24 I/O; 28-Pin-SPDIP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F2455-I/SP

• A/d Inputs: 10-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 12 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 23
• Interface: I2C/SPI/USART/USB
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 24K Bytes
• Ram Size: 2K Bytes
• Speed: 48 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

TBLRD
Syntax:
Operands:
Operation:
Status Affected: None
Encoding:
Description:
Words:
Cycles:
© 2006 Microchip Technology Inc.
Q Cycle Activity:
operation
Decode
No
Q1
(Read Program
Table Read
None
(Prog Mem (TBLPTR))
TBLPTR – No Change;
if TBLRD *+
(Prog Mem (TBLPTR))
(TBLPTR) + 1
if TBLRD *-
(Prog Mem (TBLPTR))
(TBLPTR) – 1
if TBLRD +*
(TBLPTR) + 1
(Prog Mem (TBLPTR))
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.
The TBLRD instruction can modify the value
of TBLPTR as follows:
• no change
• post-increment
• post-decrement
• pre-increment
1
2
TBLRD ( *; *+; *-; +*)
if TBLRD *
No operation
operation
TBLPTR[0] = 0: Least Significant Byte of
TBLPTR[0] = 1: Most Significant Byte of
Memory)
0000
No
Q2
0000
operation
operation
TBLPTR;
TBLPTR;
TBLPTR;
Program Memory Word
Program Memory Word
No
No
Q3
0000
TABLAT;
TABLAT;
TABLAT;
TABLAT
No operation
operation
Advance Information
TABLAT)
(Write
nn=0 *
No
Q4
10nn
=1 *+
=2 *-
=3 +*
TBLRD
Example 1:
Example 2:
Before Instruction
After Instruction
Before Instruction
After Instruction
TABLAT
TBLPTR
MEMORY (00A356h)
TABLAT
TBLPTR
TABLAT
TBLPTR
MEMORY (01A357h)
MEMORY (01A358h)
TABLAT
TBLPTR
PIC18F2450/4450
Table Read (Continued)
TBLRD
TBLRD
*+ ;
+* ;
=
=
=
=
=
=
=
=
=
=
=
DS39760A-page 249
55h
00A356h
34h
00A357h
AAh
01A357h
34h
01A358h
34h
12h
34h