[SOLVED] regarding ldr sensor....

[PRABAKARDEVA]

i had written the adc coding...but i couldn't get the output for ldr sensor.....i couldn't find the flaws in coding....can anyone help?

 

[embpic]

which controller and adc used?

 

[PRABAKARDEVA]

which controller and adc used?

pic16f877a controller

 

[jayanth.devarayanadurga]

Zip and post project and Circuit if you really need help.

 

[PRABAKARDEVA]

int main(void) {
    TRISD = 0x00;

    PORTD = 0x00;
    //adc initialize
    adc_init();
    unsigned int ldr_val;

    while (1) {
        // read channel 0
        ldr_val = adc_read(0);
        ldr_val /= 10;
         if (ldr_val > 50)
            PORTD = 0xFF;
        else
            PORTD = 0x00;
    }
    return (1);
}

 

[selva murugesan]

hi

i am not familiar in pic. but generally, i will give some points, i hope you had correct initialization in adc code and no hard ware faults. first thing is, check the ref voltage of the micro-controller ,
second thing is, check the datatype of the ldr_val

 

[PRABAKARDEVA]

hi

i am not familiar in pic. but generally, i will give some points, i hope you had correct initialization in adc code and no hard ware faults. first thing is, check the ref voltage of the micro-controller ,
second thing is, check the datatype of the ldr_val

what is fault in datatype?

 

[selva murugesan]

hi


sorry , i beg our pardon.i might be wrong , the data type is not faulty here,

 

[PRABAKARDEVA]

can u tel me that clearly...

 

[selva murugesan]

hi

i didnt see the data type of the ldr_val before, now i saw that , i thing , the output of the ADC in pic 10 bits resolution. so unsigned int is enough.

 

[jayanth.devarayanadurga]

TRISx is not set for ADC pin. ANSEx, ADCONx, CMCON, CM1CON0, CM2CON0, VRCON, CVRCON, registers if exists is not configured. LDR circuit o/p voltage range is not mentioned. uC and Fosc is not mentioned. Post Circuit and mikroC project files zipped.

 

[PRABAKARDEVA]

TRISx is not set for ADC pin. ANSEx, ADCONx, CMCON, CM1CON0, CM2CON0, VRCON, CVRCON, registers if exists is not configured. LDR circuit o/p voltage range is not mentioned. uC and Fosc is not mentioned. Post Circuit and mikroC project files zipped.

hi jayanth.....i had just posted my main file.....i had written driver file for the adc_init() which done the everything.fosc and uc mentioned in compiler.....posted that code for your verification.

 

[jayanth.devarayanadurga]

Can't help you without seeing the adc initialize code. Better zip and post project files. If you are using ADC_Init() mikroC lib function then it is not needed.

 

[PRABAKARDEVA]

void adc_init(void)
{
	ADRESH=0;
	ADRESL=0;
	RA0=0;
	TRISA0=1;
	ADCON0=0x81;
	ADCON1=0xCE;
	}
	int adc_read(unsigned char channel)
	{
		unsigned char lsb,msb;
		unsigned char result;
	ADCON0 &= ~(0x07 << 3);         
    ADCON0 |= (channel<< 3);
    __delay_ms(1);
    ADON=1;
		GO_DONE=1;
		while(GO_DONE)
		{
			;
			}
			lsb=ADRESL;
			msb=ADRESH;
			result=(msb>>8)+lsb;
			return result;
			}

may i change need to change anything?

 

[jayanth.devarayanadurga]

I hope msb and lsb are 8 bit variables, result is 16 bit variable and left justified is used for ADC result. So, use

---

Code C - [expand]
1
result = (msb << 8) + lsb;

---

or

---

Code C - [expand]
1
result = (msb << 8) | lsb;

---

ADCON0 value is wrong. Mention Fosc used and show how you calculated Tad.

 

[PRABAKARDEVA]

i had tried that justification..but i couldn't get the output.....actually i was trying to see the result of the adc by using lcd.....i got the output '24'.i don't know..how i got?

 

[jayanth.devarayanadurga]

Why don't you post the LDR interface circuit and Fosc value?

 

[PRABAKARDEVA]

fosc 1s 20mhz

 

[jayanth.devarayanadurga]

Circuit is ok. You need resistors for LEDs in real circuit. Calculate Tad for 20 MHz and set ADCS0-ADCS2 accordingly.

Remove these

---

Code C - [expand]
1
2
ADCON0 &= ~(0x07 << 3);         
ADCON0 |= (channel<< 3);

---

Use these values

---

Code C - [expand]
1
2
ADCON0=0x81;
ADCON1=0x8E;

---

 

[PRABAKARDEVA]

there is no response after changed that config jayanth......