PIC18F85K22-I/PT Microchip Technology, PIC18F85K22-I/PT Datasheet - Page 139

• Manufacturer Part Number: PIC18F85K22-I/PT
• Description: IC, 8BIT MCU, PIC18F, 64MHZ, TQFP-80
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 18Fr

Specifications of PIC18F85K22-I/PT

• Controller Family/series: PIC18
• No. Of I/o's: 69
• Eeprom Memory Size: 1KB
• Ram Memory Size: 2KB
• Cpu Speed: 64MHz
• No. Of Timers: 8
• Core Size: 8 Bit
• Program Memory Size: 32KB
• Core Processor: PIC
• Speed: 64MHz
• Connectivity: EBI/EMI, I²C, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 69
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 24x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 80-TQFP
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

10.0
10.1
All PIC18 devices include an 8 x 8 hardware multiplier
as part of the ALU. The multiplier performs an unsigned
operation and yields a 16-bit result that is stored in the
product register pair, PRODH:PRODL. The multiplier’s
operation does not affect any flags in the STATUS
register.
Making multiplication a hardware operation allows it to
be completed in a single instruction cycle. This has the
advantages of higher computational throughput and
reduced code size for multiplication algorithms and
allows PIC18 devices to be used in many applications
previously reserved for digital-signal processors. A
comparison of various hardware and software multiply
operations, along with the savings in memory and
execution time, is shown in
10.2
Example 10-1
8 unsigned multiplication. Only one instruction is
required when one of the arguments is already loaded in
the WREG register.
Example 10-2
signed multiplication. To account for the sign bits of the
arguments, each argument’s Most Significant bit (MSb)
is tested and the appropriate subtractions are done.
TABLE 10-1:
 2009-2011 Microchip Technology Inc.
8 x 8 Unsigned
8 x 8 Signed
16 x 16
Unsigned
16 x 16 Signed
Routine
8 x 8 HARDWARE MULTIPLIER
Introduction
Operation
shows the instruction sequence for an 8 x
shows the sequence to do an 8 x 8
Without Hardware Multiply
Hardware Multiply
Without Hardware Multiply
Hardware Multiply
Without Hardware Multiply
Hardware Multiply
Without Hardware Multiply
Hardware Multiply
PERFORMANCE COMPARISON FOR VARIOUS MULTIPLY OPERATIONS
Multiply Method
Table
10-1.
Program
Memory
(Words)
13
33
21
28
52
35
1
6
Cycles
PIC18F87K22 FAMILY
(Max)
242
254
69
91
28
40
1
6
EXAMPLE 10-1:
EXAMPLE 10-2:
MOVF
MULWF
MOVF
MULWF
BTFSC
SUBWF
MOVF
BTFSC
SUBWF
@ 64 MHz @ 48 MHz @ 10 MHz @ 4 MHz
62.5 ns
15.1 s
15.8 s
375 ns
4.3 s
5.6 s
1.7 s
2.5 s
ARG1, W
ARG2
ARG1, W
ARG2
ARG2, SB
PRODH, F
ARG2, W
ARG1, SB
PRODH, F
83.3 ns
20.1 s
21.2 s
500 ns
5.7 s
7.5 s
2.3 s
3.3 s
8 x 8 UNSIGNED
MULTIPLY ROUTINE
8 x 8 SIGNED MULTIPLY
ROUTINE
;
; ARG1 * ARG2 ->
; PRODH:PRODL
; ARG1 * ARG2 ->
; PRODH:PRODL
; Test Sign Bit
; PRODH = PRODH
;
; Test Sign Bit
; PRODH = PRODH
;
Time
101.6 s
27.6 s
36.4 s
96.8 s
11.2 s
16.0 s
400 ns
2.4 s
DS39960D-page 139
- ARG1
- ARG2
242 s
254 s
69 s
91 s
28 s
40 s
1 s
6 s