can anyone help me...

[kvrajasekar]

Hi,

1.I am doin UPS control operations using 16f72(assembly).I want to connect main supply to pic PORTA,this contains adc inbuilt.my confusion is how to these analog pins.to use it as digital,first should config porta as digital i/o.but to receive analog inputs can i directly use the pins without any settins.

2.PIC operates on 5v.if i connect with 230v main is required any modifications in s/w side,I think this will be taken care by h/w.

Plz correct me,if i m wrong.

[nomad]

Do not try to connect directly to mains! you will instantly fry the pic, probably start a fire, and possibly kill yourself. to measure mains voltage you need to run through a transformer to lower the voltage. it also needs to be rectified. the pics inputs must be 5v max or less if running at lower voltage. and they cannot handle negative voltages. as far as using analog inputs you set it all up. you can make pins digital or analog on a per pin basis. you'll need to reference the data sheet to see which pins the adc uses, and what registers need to be set up.

[kvrajasekar]

Thanx mr.nomad,

It is very useful,i followed ur statement and did the followin,tell me is it correct?

movlw b'00000000' ; select PORTA,0
movwf ADCON0
movlw b'00000001' ;switch on ADC
movwf ADCON0
here btfss ADCON0,2 ;checking whether conversion is in process or not
goto here
movf ADRES,0
movwf volt_val

[kvrajasekar]

and also tell me,i need to follow the above step for all analog ports?

[nomad]

that was about the extent of what I know about it. ( I don't know assembly either.)

Anyone?

[Darrel Taylor]

... did the followin,tell me is it correct?

movlw b'00000000' ; select PORTA,0
movwf ADCON0
movlw b'00000001' ;switch on ADC
movwf ADCON0
here btfss ADCON0,2 ;checking whether conversion is in process or not
goto here
movf ADRES,0
movwf volt_val

Well, since it's a PicBasic forum, first I'll say that all you need to do is

ADCIN  0, volt_val

Or the ASM version...

    movlw b'10000001' ;FOSC32, AN0, ADC ON
    movwf ADCON0
    movlw   0x07      ; 21us @ 4mhz
    movwf   Delay    
DLY1 decfsz  Delay,1  ; acquisition time
    goto DLY1    
    bsf   ADCON0, 2   ; Start an A/D conversion
here btfss ADCON0,2   ;checking whether conversion is in process or not
    goto here
    movf ADRES,0
    movwf volt_val

Note: The volt_val and Delay variables must be in BANK0 to work.

[kvrajasekar]

Hi Darrel,

Thanks lot,
Plz tell me, why u select FOSC32,whynot FOSC8.

and my final ques is how to find the rising edge(tON) and Falling Edge(tOFF).I used the following code to find this,
This is a digital i/p,
go_vol1
btfss PORTB,0 ;checking whether porta pin is set or not
goto go_vol1 ;waiting
clrf TMR0
Duty_vol1
btfsc PORTB,0 ;keep monitoring rising edge
goto Duty_vol1
movf TMR0,0
movwf volt_val

Plz give me ur suggestion to use this code,If it is correct my work will get finish.

And also i m using LCD interface.wat should be the minimum delay b/w the commands to LCD.

-thanks.

[Darrel Taylor]

Hi Darrel,

Thanks lot,
Plz tell me, why u select FOSC32,whynot FOSC8.

I chose FOSC32 because I didn't know what crystal you were using.
If you had a 20mhz crystal FOSC8 would probably not work.
But even with a 4mhz crystal, FOSC32 will still work fine.

and my final ques is how to find the rising edge(tON) and Falling Edge(tOFF).I used the following code to find this,
This is a digital i/p,
go_vol1
btfss PORTB,0 ;checking whether porta pin is set or not
goto go_vol1 ;waiting
clrf TMR0
Duty_vol1
btfsc PORTB,0 ;keep monitoring rising edge
goto Duty_vol1
movf TMR0,0
movwf volt_val

Plz give me ur suggestion to use this code,If it is correct my work will get finish.

The code shown will wait for a rising edge, then measure the duration of the high pulse. if you add the same thing again for the low pulse, you'll have both values.

go_vol1
		btfss 	PORTB,0   ; Wait for rising edge 
		goto 	go_vol1
		clrf	TMR0      ; clear TMR0 for high pulse
Duty_vol1
		btfsc	PORTB,0	  ; keep monitoring high pulse
		goto	Duty_vol1
		movf	TMR0,0    ; put TMR0 value in W reg
		clrf    TMR0      ; clear TMR0 for low pulse
		movwf	tON       ; save timer value to variable

Duty_vol2
		btfss	PORTB,0	  ; keep monitoring low pulse
		goto	Duty_vol2
		movf	TMR0,0    ; put TMR0 value in W reg
		movwf	tOFF      ; save timer value to variable

> And also i m using LCD interface.wat should be the minimum delay b/w the commands to LCD.

It varies from display to display. I think the average is around 1.6ms, but some are as high as 2.5ms for commands. 2.0ms is standard with 50us DATA delay.

hth,