DM164120-1 Microchip Technology, DM164120-1 Datasheet - Page 19

• Manufacturer Part Number: DM164120-1
• Description: BOARD DEMO PICKIT 2 LP COUNT
• Manufacturer: Microchip Technology
• Type: MCUr

Specifications of DM164120-1

• Contents: 3 Boards (1 Populated, 2 Bare)
• Processor To Be Evaluated: PIC16F690
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC16
• Silicon Core Number: PIC16F
• Silicon Family Name: PIC16F6xxx
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: 28-pin PIC16C, 16F, 18C, 18F
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

© 2005 Microchip Technology Inc.
3.2.2
The first lesson showed how to turn on a LED, this lesson shows how to make it blink.
While this might seem a trivial change from Lesson 1, the reasons will soon become
apparent.
New Instructions
EXAMPLE 3-2:
While adding a BCF instruction and making it loop will make it blink, it will blink so fast
you won’t see it. It will only look dim. That loop requires 4 instruction times to execute.
The first instruction turns it on. The second one turns it off. The GOTO takes two instruc-
tion times, which means it will be on for 25% of the time.
As configured, the PICmicro executes 1 million instructions per second. At this rate, the
blinking needs to be slowed down so that the blinking can be seen, which can be done
by using a delay loop.
Note:
CLRF
INCF
DECF
INCFSZ
DECFSZ
GOTO
Loop
BSF
BCF
GOTO
Lesson 2: Delay Loop (Blink a LED)
Counting cycles – Relating clock speed to instruction speed. The processor
requires 4 clocks to execute an instruction. Since the internal oscillator as
used in these lessons runs at 4 MHz, the instruction rate is 1 MHz.
PORTC,0
PORTC,0
Loop
PICkit 2, LESSON 2: BLINK
Clear file register
Increment file register
Decrement file register
Increment file register, Skip next instruction if zero
Decrement file register, Skip next instruction if zero
Jump to a new location in the program
;turn on LED C0
;turn off LED C0
;do it again
LPC Demo Board Lessons
DS51556A-page 15