How to start PIC16F676 ...??

Ian Rogers · Mar 11, 2012

Ritesh!! I never paid any mind to the delay.... I though you had engineered it for a minimum time for simulation.

There was no overflow!

Code:

delay

	movlw 0xff
	movwf PORTC 
	movlw 0fh
	movwf 0x21
	dECfsz 0x21,f
        goto $-1
	clrf PORTC
	RETURN
 
end

The delay as a delay.

koolguy · Mar 11, 2012

Ritesh!! I never paid any mind to the delay.... I though you had engineered it for a minimum time for simulation.

There was no overflow!

Cool work....

I found the meaning from here..!!( a little search)

$ means the address you're at. $-1 means one address up. You can use it when you check a bit. Example.

start
BTFSS PORTA,1
GOTO start

instead you can write:
BTFSS PORTA,1
GOTO $-1

koolguy · Mar 13, 2012

Hi,

how to change the freq of pulse as in case of duty cycle we can do by adding delay...(like PWM )

Ian Rogers · Mar 13, 2012

Show me what you mean...

koolguy · Mar 13, 2012

I have seen a program which blink LED at different duty cycles simply by adding delay to its subroutine, but in case of changing the freq of blinking LED ?
like we do this in PWM we change the duty cycle and freq of that pulse also.
So, i want to know how we can change the freq not by crystal(oscillator) internally by code??

Ian Rogers · Mar 14, 2012

If you take a look at Nigel's tutorials......Study them a bit...... There are ways to implement delays... Most programmers write two delay functions... One with uS delay and one with mS delay.

This way you can call a delay ( with the amount of uS / mS in W ) and have any delay you need.... Nigel has uS delays AND mS delays.

koolguy · Mar 14, 2012

Hi,

If i want to use this code than i will convert it to Hex by map lab or OSHON then program it to PIC16f676 then make a LED to corresponding pin will thi swork or more step to folows

Code:

;include "P16F676.inc"		;include the defaults for the chip
	__config 0x3114			;sets the configuration settings (oscillator type etc.)
							; HERE SET TO INTERNAL OSCILLATOR 4MHZ
	ORG 0
	GOTO INIT
 
INIT
	CLRF OPTION_REG
	BSF STATUS,RP0
	CLRF VRCON
	MOVLW 0x3f
	MOVWF TRISA 	; porta as input
	MOVLW 0x0
	CLRF ANSEL 	; disable ADC
	MOVWF TRISC 	; portb as output
	BCF STATUS,RP0
	MOVLW 0x7
	MOVWF CMCON
 
START
 
	btfss PORTA,1 	; test bit 1
	call delay
 
	GOTO START
 
delay
	movlw 0xff
	movwf PORTC 
	movlw 0fh
	movwf 0x21
	dECfsz 0x21,f
	clrf PORTC
	RETURN
 
end

ericgibbs · Mar 14, 2012

hi Ritesh,
This code fragment is STILL wrong.

Code:

delay
	movlw 0xff
	movwf PORTC 
	movlw 0fh; you are keeping the counter at 0Fh and only decrementing to 0Eh
	movwf 0x21
	dECfsz 0x21,f
	clrf PORTC
	RETURN

koolguy · Mar 14, 2012

ericgibbs said:
hi Ritesh,
This code fragment is STILL wrong.
delay
movlw 0xff
movwf PORTC
movlw 0fh; you are keeping the counter at 0Fh and only decrementing to 0Eh
movwf 0x21
dECfsz 0x21,f
clrf PORTC

RETURN

Hi again,

I have notice that before we can use it by adding this after that decrement instruction GOTO $-1.
anyway i was asking of blinking LED code and i have posted this code. sorry.

koolguy · Mar 14, 2012

Wp100 said:

Hi,

As Ian says use Nigels tutorials, here is lesson 1, led flasher, but modified for your chip.

Just note the differences and then you can apply then to the rest of his code examples.

The picture shows how to wire the led, though you must add +5v and 0v .

Code:

;Tutorial 1.2 - Nigel Goodwin 2002  ; MODIFIED FOR PIC16F676

	LIST	p=16F676		;tell assembler what chip we are using
	include "P16F676.inc"	;include the defaults for the chip
	__config 0x3D14			;sets the configuration settings (oscillator type etc.)
							; HERE SET TO INTERNAL OSCILLATOR 4MHZ

	cblock 	0x20 			;start of general purpose registers
		count1 			;used in delay routine
		counta 			;used in delay routine 
		countb 			;used in delay routine
	endc
	
	org	0x0000			;org sets the origin, 0x0000 for the 16F628,
					;this is where the program starts running	

	bcf 	STATUS,RP0 	;Bank 0
	clrf 	PORTA 		;Init PORTA
	movlw	05h 		;Set RA<2:0> to 
	movwf	CMCON 		;digital I/O
	bsf 	STATUS,RP0 	;Bank 1
	clrf	ANSEL 		;digital I/O
	movlw 	00h 		; 
	movwf 	TRISA 		;as outputs

   	movlw 	b'00000000'	;set PortC all outputs
   	movwf 	TRISC
	movwf	TRISA		;set PortA all outputs
	bcf		STATUS,	RP0	;select bank 0

Loop	
	movlw	0xff
	movwf	PORTA			;set all bits on
	movwf	PORTC
	nop				;the nop's make up the time taken by the goto
	nop				;giving a square wave output
	call	Delay			;this waits for a while!
	movlw	0x00
	movwf	PORTA
	movwf	PORTC			;set all bits off
	call	Delay
	goto	Loop			;go back and do it again

Delay	movlw	d'250'			;delay 250 ms (4 MHz clock)
	movwf	count1
d1	movlw	0xC7
	movwf	counta
	movlw	0x01
	movwf	countb
Delay_0
	decfsz	counta, f
	goto	$+2
	decfsz	countb, f
	goto	Delay_0

	decfsz	count1	,f
	goto	d1
	retlw	0x00

	end

Now i want to Go with code on my PIC chip hardware..
please tell how to make its board ??
here is my HEX code please check is that fine....??

Nigel Goodwin · Mar 14, 2012

RITESH KAKKAR said:
Now i want to Go with code on my PIC chip hardware..
please tell how to make its board ??

All the boards for my tutorials are on my site, veroboard designs so anyone can easily build them.

ericgibbs · Mar 14, 2012

hi,
Run this in Oshonsoft.. I have set the Delay to suit simulation. It set PORTC On/Off

Code:

	LIST	p=16F676		;tell assembler what chip we are using
	include "P16F676.inc"	;include the defaults for the chip
	__config 0x3D14			;sets the configuration settings (oscillator type etc.)
							
	errorlevel -302, -207
	
CounterA  equ 0x20
CounterB  equ 0x21
CounterC  equ 0x22
CounterD  equ 0x23
	
	; HERE SET TO INTERNAL OSCILLATOR 4MHZ
	ORG 0
	GOTO INIT
 
INIT
	bcf STATUS,RP0
	clrf PORTA
	MOVLW 0x07
	MOVWF CMCON

	BSF STATUS,RP0
	clrf ANSEL 	; disable ADC

	movlw 0x0f
	MOVWF TRISA 	; porta as inp
	
	clrf TRISC	 ; portc as out	
	BCF STATUS,RP0
 	 
START
	call delay
	movlw 0xff
	movwf PORTC 
	call delay
	clrf PORTC
	GOTO START
	
;PIC Time Delay = 0.50000200 s with Osc = 4000000 Hz
delay:		movlw	.1
		movwf	CounterC
		movlw	.10
		movwf	CounterB
		movlw	.50
		movwf	CounterA
loop		decfsz	CounterA,1
		goto	loop
		decfsz	CounterB,1
		goto	loop
		decfsz	CounterC,1
		goto	loop
		retlw	0	
		
		end

Ian Rogers · Mar 14, 2012

Ritesh...

These are the delay routines

Code:

Del0	retlw	0x00			;delay 0mS - return immediately
Del1	movlw	d'1'			;delay 1mS
	goto	Delay
Del5	movlw	d'5'			;delay 5mS
	goto	Delay
Del10	movlw	d'10'			;delay 10mS
	goto	Delay
Del20	movlw	d'20'			;delay 20mS
	goto	Delay
Del50	movlw	d'50'			;delay 50mS
	goto	Delay
Del100	movlw	d'100'			;delay 100mS
	goto	Delay
Del250	movlw	d'250'			;delay 250 ms
Delay	movwf	count1
d1	movlw	0xC7			;delay 1mS
	movwf	counta
	movlw	0x01
	movwf	countb
Delay_0
	decfsz	counta, f
	goto	$+2
	decfsz	countb, f
	goto	Delay_0

	decfsz	count1	,f
	goto	d1
	retlw	0x00

Put this at the end of your code and you can call any of the above... (provided you use a 4mhz Xtal)

koolguy · Mar 14, 2012

hi,
Run this in Oshonsoft.. I have set the Delay to suit simulation. It set PORTC On/Off

Yes, this is working...The HEX file i posted wil that work with that code given by Wp100?

Ian Rogers · Mar 14, 2012

You cant fail now you have three of us onboard.....

koolguy · Mar 14, 2012

Please provide one single program I am confused.

Ian Rogers · Mar 14, 2012

Why are you confused..... Its you who needs to choose what delays you require.... you now have three sets to choose from.

koolguy · Mar 14, 2012

Ok, i am using this code of Eric...

Code:

	LIST	p=16F676		;tell assembler what chip we are using
	include "P16F676.inc"	;include the defaults for the chip
	__config 0x3D14			;sets the configuration settings (oscillator type etc.)
 
	errorlevel -302, -207
 
CounterA  equ 0x20
CounterB  equ 0x21
CounterC  equ 0x22
CounterD  equ 0x23
 
	; HERE SET TO INTERNAL OSCILLATOR 4MHZ
	ORG 0
	GOTO INIT
 
INIT
	bcf STATUS,RP0
	clrf PORTA
	MOVLW 0x07
	MOVWF CMCON
 
	BSF STATUS,RP0
	clrf ANSEL 	; disable ADC
 
	movlw 0x0f
	MOVWF TRISA 	; porta as inp
 
	clrf TRISC	 ; portc as out	
	BCF STATUS,RP0
 
START
	call delay
	movlw 0xff
	movwf PORTC 
	call delay
	clrf PORTC
	GOTO START
 
;PIC Time Delay = 0.50000200 s with Osc = 4000000 Hz
delay:		movlw	.1
		movwf	CounterC
		movlw	.10                             ; changing its value to .30 for more delay.!!!!
		movwf	CounterB
		movlw	.50
		movwf	CounterA
loop		decfsz	CounterA,1
		goto	loop
		decfsz	CounterB,1
		goto	loop
		decfsz	CounterC,1
		goto	loop
		retlw	0	
 
		end

I am attaching the HEX code of it please have a look whether is right??
and i have assembled it by MAP LAB

koolguy · Mar 14, 2012

Ok, i am using this code of Eric...

Code:

	LIST	p=16F676		;tell assembler what chip we are using
	include "P16F676.inc"	;include the defaults for the chip
	__config 0x3D14			;sets the configuration settings (oscillator type etc.)
 
	errorlevel -302, -207
 
CounterA  equ 0x20
CounterB  equ 0x21
CounterC  equ 0x22
CounterD  equ 0x23
 
	; HERE SET TO INTERNAL OSCILLATOR 4MHZ
	ORG 0
	GOTO INIT
 
INIT
	bcf STATUS,RP0
	clrf PORTA
	MOVLW 0x07
	MOVWF CMCON
 
	BSF STATUS,RP0
	clrf ANSEL 	; disable ADC
 
	movlw 0x0f
	MOVWF TRISA 	; porta as inp
 
	clrf TRISC	 ; portc as out	
	BCF STATUS,RP0
 
START
	call delay
	movlw 0xff
	movwf PORTC 
	call delay
	clrf PORTC
	GOTO START
 
;PIC Time Delay = 0.50000200 s with Osc = 4000000 Hz
delay:		movlw	.1
		movwf	CounterC
		movlw	.10                             ; changing its value to .30 for more delay.!!!!
		movwf	CounterB
		movlw	.50
		movwf	CounterA
loop		decfsz	CounterA,1
		goto	loop
		decfsz	CounterB,1
		goto	loop
		decfsz	CounterC,1
		goto	loop
		retlw	0	
 
		end

I am attaching the HEX code of it please have a look whether is right??
and i have assembled it by MAP LAB

koolguy · Mar 14, 2012

Will this circuit will work with this code??

How to start PIC16F676 ...??

User Extraordinaire

Active Member

Active Member

User Extraordinaire

Active Member

User Extraordinaire

Active Member

Well-Known Member

Active Member

Active Member

Super Moderator

Well-Known Member

User Extraordinaire

Active Member

User Extraordinaire

Active Member

User Extraordinaire

Active Member

Active Member

Active Member

Similar threads

Privacy & Transparency

Privacy & Transparency