PIC18F8525-I/PT Microchip Technology, PIC18F8525-I/PT Datasheet - Page 48

• Manufacturer Part Number: PIC18F8525-I/PT
• Description: IC PIC MCU FLASH 24KX16 80TQFP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F8525-I/PT

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 69
• Program Memory Size: 48KB (24K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 3.75K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 16x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 80-TFQFP
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 3840 B
• Interface Type: MSSP, SPI, I2C, EUSART
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 69
• Number Of Timers: 2 x 8 bit
• Operating Supply Voltage: 4.2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, ICE4000, DV164136, DM163032
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 16 bit
• For Use With: XLT80PT3 - SOCKET TRAN ICE 80MQFP/TQFPAC164320 - MODULE SKT MPLAB PM3 80TQFPAC174011 - MODULE SKT PROMATEII 80TQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PIC18F6525/6621/8525/8621
4.7.1
The PIC18F6525/6621/8525/8621 devices have four
two-word instructions: MOVFF, CALL, GOTO and LFSR.
The second word of these instructions has the 4 MSBs
set to ‘1’s and is a special kind of NOP instruction. The
lower 12 bits of the second word contain data to be
used by the instruction. If the first word of the instruction
is executed, the data in the second word is accessed.
EXAMPLE 4-3:
4.8
Look-up tables are implemented two ways. These are:
• Computed GOTO
• Table Reads
4.8.1
A computed GOTO is accomplished by adding an offset
to the program counter (ADDWF PCL).
A look-up table can be formed with an ADDWF PCL
instruction and a group of RETLW 0xnn instructions.
WREG is loaded with an offset into the table before exe-
cuting a call to that table. The first instruction of the called
EXAMPLE 4-4:
DS39612B-page 46
CASE 1:
Object Code
CASE 2:
Object Code
0110 0110 0000 0000
1100 0001 0010 0011
1111 0100 0101 0110
0010 0100 0000 0000
0110 0110 0000 0000
1100 0001 0010 0011
1111 0100 0101 0110
0010 0100 0000 0000
MAIN: ORG
…
TABLE MOVF
Look-up Tables
MOVLW 0x00
CALL
ORG
RLNCF W, W
ADDWF PCL
RETLW ‘A’
RETLW ‘B’
RETLW ‘C’
RETLW ‘D’
RETLW ‘E’
END
TWO-WORD INSTRUCTIONS
COMPUTED GOTO
0x0000
TABLE
0x8000
PCL, F
TWO-WORD INSTRUCTIONS
COMPUTED GOTO USING AN OFFSET VALUE
; A simple read of PCL will update PCLATH, PCLATU
; Multiply by 2 to get correct offset in table
; Add the modified offset to force jump into table
Source Code
TSTFSZ
MOVFF
Source Code
TSTFSZ
ADDWF
ADDWF
MOVFF
REG1
REG1, REG2 ; No, execute 2-word instruction
REG3
REG1
REG1, REG2 ; Yes
REG3
; is RAM location 0?
; 2nd operand holds address of REG2
; continue code
; is RAM location 0?
; 2nd operand becomes NOP
; continue code
If the second word of the instruction is executed by itself
(first word was skipped), it will execute as a NOP. This
action is necessary when the two-word instruction is
preceded by a conditional instruction that changes the
PC. A program example that demonstrates this concept
is shown in Example 4-3. Refer to Section 25.0
“Instruction Set Summary” for further details of the
instruction set.
routine is the ADDWF PCL instruction. The next instruction
executed will be one of the RETLW 0xnn instructions that
returns the value 0xnn to the calling function.
The offset value (value in WREG) specifies the number
of bytes that the program counter should advance.
In this method, only one data byte may be stored in
each instruction location and room on the return
address stack is required.
Note:
The ADDWF
update PCLATH and PCLATU. A read
operation on PCL must be performed to
update PCLATH and PCLATU.
 2005 Microchip Technology Inc.
PCL instruction does not