PIC18F43K22T-I/ML Microchip Technology Inc., PIC18F43K22T-I/ML Datasheet - Page 73

• Manufacturer Part Number: PIC18F43K22T-I/ML
• Description: 8KB, FLASH, 3968BYTES-RAM, 8-BIT FAMILY, NANOWATT XLP, 44 QFN 8X8X0.9MM T/R
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F43K22T-I/ML

• A/d Inputs: 28-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 16 MIPS
• Eeprom Memory: 1K Bytes
• Input Output: 35
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin QFN
• Programmable Memory: 8K Bytes
• Ram Size: 512 Bytes
• Speed: 48 MHz
• Temperature Range: –40 to 125 °C
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 1.8-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part

EXAMPLE 5-1:
5.1.4
There may be programming situations that require the
creation of data structures, or look-up tables, in
program memory. For PIC18 devices, look-up tables
can be implemented in two ways:
• Computed GOTO
• Table Reads
5.1.4.1
A computed GOTO is accomplished by adding an offset
to the program counter. An example is shown in
Example
A look-up table can be formed with an ADDWF PCL
instruction and a group of RETLW nn instructions. The
W register is loaded with an offset into the table before
executing a call to that table. The first instruction of the
called routine is the ADDWF PCL instruction. The next
instruction executed will be one of the RETLW
instructions that returns the value ‘nn’ to the calling
function.
The offset value (in WREG) specifies the number of
bytes that the program counter should advance and
should be multiples of 2 (LSb = 0).
In this method, only one data byte may be stored in
each instruction location and room on the return
address stack is required.
EXAMPLE 5-2:
 2010 Microchip Technology Inc.
CALL SUB1, FAST
SUB1
ORG
TABLE
RETURN, FAST
5-2.




MOVF
CALL
nn00h
ADDWF
RETLW
RETLW
RETLW
.
.
.
LOOK-UP TABLES IN PROGRAM
MEMORY
Computed GOTO
OFFSET, W
TABLE
PCL
nnh
nnh
nnh
FAST REGISTER STACK
CODE EXAMPLE
COMPUTED GOTO USING
AN OFFSET VALUE
;STATUS, WREG, BSR
;SAVED IN FAST REGISTER
;STACK
;RESTORE VALUES SAVED
;IN FAST REGISTER STACK
Preliminary
nn
5.1.4.2
A better method of storing data in program memory
allows two bytes of data to be stored in each instruction
location.
Look-up table data may be stored two bytes per
program word by using table reads and writes. The
Table Pointer (TBLPTR) register specifies the byte
address and the Table Latch (TABLAT) register
contains the data that is read from or written to program
memory. Data is transferred to or from program
memory one byte at a time.
Table read and table write operations are discussed
further in Section 6.1 “Table Reads and Table
Writes”.
PIC18(L)F2X/4XK22
Table Reads and Table Writes
DS41412D-page 73