PIC18F452-I/P Microchip Technology, PIC18F452-I/P Datasheet - Page 73

• Manufacturer Part Number: PIC18F452-I/P
• Description: IC MCU FLASH 16KX16 EE 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F452-I/P

• Program Memory Type: FLASH
• Program Memory Size: 32KB (16K x 16)
• Package / Case: 40-DIP (0.600", 15.24mm)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 34
• Eeprom Size: 256 x 8
• Ram Size: 1.5K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 1.5 KB
• Interface Type: MSSP/SPI/I2C/PSP/USART
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 34
• Number Of Timers: 4
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 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, DM163022
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 10-bit
• Package: 40PDIP
• Device Core: PIC
• Family Name: PIC18
• Maximum Speed: 40 MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 444-1001 - DEMO BOARD FOR PICMICRO MCUACICE0206 - ADAPTER MPLABICE 40P 600 MIL
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: PIC18F452I/P; Q1176145

7.0
7.1
An 8 x 8 hardware multiplier is included in the ALU of
the PIC18FXX2 devices. By making the multiply a
hardware operation, it completes in a single instruction
cycle. This is an unsigned multiply that gives a 16-bit
result. The result is stored into the 16-bit product regis-
ter pair (PRODH:PRODL). The multiplier does not
affect any flags in the ALUSTA register.
TABLE 7-1:
7.2
Example 7-1 shows the sequence to do an 8 x 8
unsigned multiply. Only one instruction is required
when one argument of the multiply is already loaded in
the WREG register.
Example 7-2 shows the sequence to do an 8 x 8 signed
multiply. To account for the sign bits of the arguments,
each argument’s Most Significant bit (MSb) is tested
and the appropriate subtractions are done.
EXAMPLE 7-1:
MOVF
MULWF
16 x 16 unsigned
2002 Microchip Technology Inc.
8 x 8 unsigned
16 x 16 signed
8 x 8 signed
Routine
8 X 8 HARDWARE MULTIPLIER
Introduction
Operation
ARG1, W
ARG2
PERFORMANCE COMPARISON
8 x 8 UNSIGNED
MULTIPLY ROUTINE
Without hardware multiply
Without hardware multiply
Without hardware multiply
Without hardware multiply
;
; ARG1 * ARG2 ->
;
Hardware multiply
Hardware multiply
Hardware multiply
Hardware multiply
Multiply Method
PRODH:PRODL
Program
Memory
(Words)
13
33
21
24
52
36
1
6
Making the 8 x 8 multiplier execute in a single cycle
gives the following advantages:
• Higher computational throughput
• Reduces code size requirements for multiply
The performance increase allows the device to be used
in applications previously reserved for Digital Signal
Processors.
Table 7-1 shows a performance comparison between
enhanced devices using the single cycle hardware mul-
tiply, and performing the same function without the
hardware multiply.
EXAMPLE 7-2:
Example 7-3 shows the sequence to do a 16 x 16
unsigned multiply. Equation 7-1 shows the algorithm
that is used. The 32-bit result is stored in four registers,
RES3:RES0.
EQUATION 7-1:
RES3:RES0
MOVF
MULWF
BTFSC
SUBWF
MOVF
BTFSC
SUBWF
algorithms
Cycles
(Max)
242
254
69
91
24
36
1
6
ARG1,
ARG2
ARG2,
PRODH, F
ARG2,
ARG1,
PRODH, F
=
=
@ 40 MHz
24.2 s
25.4 s
100 ns
600 ns
6.9 s
9.1 s
2.4 s
3.6 s
ARG1H:ARG1L ARG2H:ARG2L
(ARG1H ARG2H 2
(ARG1H ARG2L 2
(ARG1L ARG2H 2
(ARG1L ARG2L)
SB
SB
W
W
8 x 8 SIGNED MULTIPLY
ROUTINE
16 x 16 UNSIGNED
MULTIPLICATION
ALGORITHM
PIC18FXX2
; ARG1 * ARG2 ->
; PRODH:PRODL
; Test Sign Bit
; PRODH = PRODH
;
; Test Sign Bit
; PRODH = PRODH
;
@ 10 MHz
102.6 s
27.6 s
36.4 s
96.8 s
14.4 s
400 ns
Time
2.4 s
9.6 s
DS39564B-page 71
- ARG1
8
8
16
- ARG2
) +
) +
) +
@ 4 MHz
242 s
254 s
69 s
91 s
24 s
36 s
1 s
6 s