pic16f877a MR TAHMID YOU PLEASE REPLAY

[Drqadeer]

HELLO MR TAHMID,,, Ive read many posts and blogs by you and they are a lot of helpfull.
so i am going to define problem , if you read then please tell me in detail
i am going to use PIC16f877a, i want to use its analog inputs as analog inputs and Rc0 to Rc3 as digital input.... i am confsed on registers ADCON0 and ADCON1.....
what values i have to set to them..... using MIKROC 8.2 and 8Mhz crysal,,, also tell me which pf capicitors are better for 8Mhz , 12Mhz and 20Mhz

 

[jpsganesh]

sorry I'm not Mr TAHMID. if my answer is valid use it otherwise ignore it.

also tell me which pf capicitors are better for 8Mhz , 12Mhz and 20Mhz

22pf will work fine for x-tals from 4MHz to 20MHz. (15pf to 33pf will work fine)


ADCON0=0X81;
ADCON1=0X84;

ADCON0


ADCON1


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I read some of MR TAHMID posts. Really awesome especially abt his father and his guidance from school hood.

 

[Drqadeer]

oh thanks a lot,,,,, i'll use it soon and replay you

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i've checked values given by you on the datasheet registers, but it is quit different to my requirments...
i want to use all analog pins as analog and PORTC 0 to 3 PINS as Digital i/p.
TRISC=0x0f;
what about ADCON0 nd ADCON1
i think not
ADCON0=0x81;
ADOCON1=0x84;

 

[jpsganesh]

TRISC=0x0f;    // 0f = 0000 1111   PORT C LSB 4 bits are digital I/P

ADCON0=0X81;
ADCON1=0X80;   // all AN pins are configured as Analog I/P pins. PCFG0 - PCFG3 are A/D port config bits

u need to select the analog channel before performing A/D conversion by changing CHS0 - CHS2 bits

u can use GO/DONE bit to perform A/D conversion.

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accordingly set TRISA and TRISE as I/P.

 

[Drqadeer]

thanks a lot, it works
i was taking analog voltage because i want to create veriable delay using VDelay function of mikroC , but it is not working
may be there is some problem in conversion.
so please some guidance about it, how to make a veriable delay using this analog input, say having 5V at input delay of 5s is required.
i was using some like that.
adc_rd=adc_read(2);
adc_rd=adc_rd/1023;
adc_rd=adc_rd*5000;
portb=oxff;
Vdelay(adc_rd);
portb=~portb;
Vdelay(adc_rd);
but it is not working, LEDs on portB are on for a long period (unknown period)

 

[jpsganesh]

u can create ur own delay function using while or timer
so u can calculate the time easily based on the oscillator value (and setting like prescaler)

 

[Drqadeer]

i cant understand.
any example
delay should veriable using an external veriable resistor on pic

 

[jpsganesh]

simple delay using while loop

void delay(unsigned long);   // function init

void main()
{
delay(500); 
// or 
delay(i); 
// or
delay(AD_result);
// or
delay(AD_result*2);  
// or
delay(AD_result+5);

}

// delay function
void delay(unsigned long del_del)
{
	while(del_del--);
}