[SOLVED] pic18f43k22 adc wont work

[bhan1992]

#include <p18f43k22.h>
#include <adc.h>
#include <stdlib.h>
#include <delays.h>

int result, increment;

void main (void)
{
	OpenADC(ADC_FOSC_32 & ADC_RIGHT_JUST & ADC_2_TAD, ADC_REF_VDD_VSS, ADC_CH0 & ADC_INT_OFF );

	TRISB = 0;

	while(1)
	{
		SetChanADC(ADC_CH0);
		ConvertADC();
		while(BusyADC());
		result = ReadADC();

		if (result < 550)
		{
			PORTB = 1;	
		}
		else
		{
			PORTB = 0;
		}
	}
	CloseADC();
}

i tried to connect a potentiometer at the analog channel 0 (pin 2 of the pic) but the led in pin rb5 just wont light up.
does the code has something missing?

 

[Venkadesh_M]

yeah, PORTB = 1 means RB0 is the output....

otherwise you have to write

---

Code C - [expand]
1
2
TRISB5 = 0;
RB5 = 1;

---

 

[Jinzpaul4u]

Hi,

PORTB=0xFF;

How much voltage are you feeding through POT.

may be ADC values are greater than 550. try below calculation for converting adc reading to voltage.

const float maxAdcBits = 4095.0f; // Using Float for clarity if it 12 bit(2^12=4095)
const float maxVolts = 5.0f; // Using Float for clarity
const float voltsPerBit = (maxVolts / maxAdcBits);

float yourVoltage = ADCReading * voltsPerBit;


try these and update me.

Best regards,

 

[forforum]

Yes, try to measure RB0 pin

yeah, PORTB = 1 means RB0 is the output....

otherwise you have to write

---

Code C - [expand]
1
2
TRISB5 = 0;
RB5 = 1;

---

 

[bhan1992]

im sorry but i don't get you.

yeah, PORTB = 1 means RB0 is the output....

otherwise you have to write

---

Code C - [expand]
1
2
TRISB5 = 0;
RB5 = 1;

---

- - - Updated - - -

im feeding the pot with 5v. i try to tune the pot but led doesnt light up

Hi,

TRISB=0xFF;

How much voltage are you feeding through POT.

may be ADC values are greater than 550. try below calculation for converting adc reading to voltage.

const float maxAdcBits = 4095.0f; // Using Float for clarity if it 12 bit(2^12=4095)
const float maxVolts = 5.0f; // Using Float for clarity
const float voltsPerBit = (maxVolts / maxAdcBits);

float yourVoltage = ADCReading * voltsPerBit;


try these and update me.

Best regards,

 

[mathespbe]

im sorry but i don't get you.


- - - Updated - - -

im feeding the pot with 5v. i try to tune the pot but led doesnt light up

Instead of using PORTB=1; just use RB5=1; and PORTB=0; use RB5=0;

If it doesn't work yet check the ADC values...

 

[Venkadesh_M]

im sorry but i don't get you.

check the output in RB0..

 

[Jinzpaul4u]

Hello again,

im sorry but i don't get you.

PORT B is also an 8 bit bi-directional PORT. Its direction controlled and maintained by TRIS B data direction register. Setting the TRIS B into logic ‘1’ makes the corresponding “PORT B” pin as an input. Clearing the TRIS B bit make PORT B as an output.

im feeding the pot with 5v. i try to tune the pot but led doesnt light up

Try these too..

if (result >= 550)
		{
			PORTB = 1;	
		}
		else
		{
			PORTB = 0;
		}

Update me.

Best regards,

- - - Updated - - -

#include <p18f43k22.h>
#include <adc.h>
#include <stdlib.h>
#include <delays.h>

int result, increment;

void main (void)
{
	OpenADC(ADC_FOSC_32 & ADC_RIGHT_JUST & ADC_2_TAD, ADC_REF_VDD_VSS, ADC_CH0 & ADC_INT_OFF );

	TRISB = 0;

	while(1)
	{
		SetChanADC(ADC_CH0);
		ConvertADC();
		while(BusyADC());
		result = ReadADC();

		if (result < 550)
		{
			PORTB = 1;	
		}
		else
		{
			PORTB = 0;
		}
	}
	CloseADC();
}

i tried to connect a potentiometer at the analog channel 0 (pin 2 of the pic) but the led in pin rb5 just wont light up.
does the code has something missing?

Try these code and update me.

#include <p18f43k22.h>
#include <adc.h>
#include <stdlib.h>
#include <delays.h>

float result, increment;
const unsigned long maxAdcBits = 4095; //  if it 12 bit(2^12=4095)
const unsigned long  maxVolts = 5000; // 
const float voltsPerBit = (maxVolts / maxAdcBits);

void main (void)
{
	OpenADC(ADC_FOSC_32 & ADC_RIGHT_JUST & ADC_2_TAD, ADC_REF_VDD_VSS, ADC_CH0 & ADC_INT_OFF );

	TRISB = 0x00;
	TRISA=0x01;// RA0 for analog channel input.
	ANSELA=0x01; // analog pin select
        PIR1bits.ADIF = 0; //make sure A/D Int not set

	while(1)
	{
		SetChanADC(ADC_CH0);
		ConvertADC();
		while(BusyADC());
  		result = ReadADC();
              result  = result * voltsPerBit;// analog to Voltage conversion.
		if (result < 550)// if less than 550mV
		{
			PORTB = 1;	
		}
		else
		{
			PORTB = 0;
		}
	}
	CloseADC();
}

 

[bhan1992]

it works but there is a delay. eg: when i turn the pot to the max, i have to wait for about 15 sec before the LED turns on. and turn i turn the pot the other way, i have to wait another 15 sec before the LED is turned off.
my modified code below

#include <p18f43k22.h>
#include <adc.h>
#include <stdlib.h>
#include <delays.h>

int result, increment;

void main (void)
{
	OpenADC(ADC_FOSC_32 & ADC_RIGHT_JUST & ADC_2_TAD, ADC_REF_VDD_VSS, ADC_INT_OFF );

	TRISB = 0;
	while(1)
	{
		SetChanADC(ADC_CH0);
		ConvertADC();
		while(BusyADC());
		result = ReadADC();

		if (result >= 550)
		{
			PORTBbits.RB5 = 1;	
		}
		else
		{
			PORTBbits.RB5 = 0;
		}
	}
	CloseADC();
}

Hello again,


PORT B is also an 8 bit bi-directional PORT. Its direction controlled and maintained by TRIS B data direction register. Setting the TRIS B into logic ‘1’ makes the corresponding “PORT B” pin as an input. Clearing the TRIS B bit make PORT B as an output.


Try these too..

if (result >= 550)
		{
			PORTB = 1;	
		}
		else
		{
			PORTB = 0;
		}

Update me.

Best regards,

- - - Updated - - -



Try these code and update me.

#include <p18f43k22.h>
#include <adc.h>
#include <stdlib.h>
#include <delays.h>

float result, increment;
const unsigned long maxAdcBits = 4095; //  if it 12 bit(2^12=4095)
const unsigned long  maxVolts = 5000; // 
const float voltsPerBit = (maxVolts / maxAdcBits);

void main (void)
{
	OpenADC(ADC_FOSC_32 & ADC_RIGHT_JUST & ADC_2_TAD, ADC_REF_VDD_VSS, ADC_CH0 & ADC_INT_OFF );

	TRISB = 0x00;
	TRISA=0x01;// RA0 for analog channel input.
	ANSELA=0x01; // analog pin select
        PIR1bits.ADIF = 0; //make sure A/D Int not set

	while(1)
	{
		SetChanADC(ADC_CH0);
		ConvertADC();
		while(BusyADC());
  		result = ReadADC();
              result  = result * voltsPerBit;// analog to Voltage conversion.
		if (result < 550)// if less than 550mV
		{
			PORTB = 1;	
		}
		else
		{
			PORTB = 0;
		}
	}
	CloseADC();
}

- - - Updated - - -

[update]
Problem solved, it was the configuration words. i forget to set to XT which im using @ 4MHz. after setting the conf words, it works perfect now. thnx guys!

 

[Jinzpaul4u]

Wow that is really great...