PIC16F877A – Interfacing POT(ADC)

PIC16F877A mini development board has a POT connected to pin RA0 i.e, channel0 via jumper J16. Turning the POT varies the input to RA0 from 0 to 5V. Sample code to check the ADC module of PIC16F877A with potentiometer is given below. The output is displayed on LCD and the variation can be checked with the POT.

SchematicNote: To use potentiometer, don’t forget to short jumper J16. Leaving it open frees RA0 and it can be used for any other desired purpose.

Sample Code

/*************************************************************************
                           HEADER FILES
**************************************************************************/
#include<pic.h>                 

/*************************************************************************
                       FUNCTION DECLARATIONS
**************************************************************************/             
void LCD_Command(int com);
void LCD_Data(int data);           
void Display(const char Adr, const char *LCD);  
void Delay_us(char Delay);
void Delay_100us(unsigned long int Delay); 

/*************************************************************************
                       VARIABLE DECLARATIONS
**************************************************************************/
int k,result;
char array[5];

/*************************************************************************
                           MAIN FUNCTION
**************************************************************************/
void main()                    
{
 TRISA = 0XFF;                /* PORTA configured as i/p                 */
 TRISC = 0X00;                /* LCD control lines configured as o/p     */
 TRISD = 0X00;                /* LCD data lines configured as o/p        */

 LCD_Command(0X30);           /* LCD specification command               */
 Delay_us(35);
 LCD_Command(0X30);           /* LCD specification command               */
 Delay_us(35);
 LCD_Command(0X30);           /* LCD specification command               */
 Delay_us(35);
 LCD_Command(0X38);           /* Double Line Display Command             */
 LCD_Command(0X06);           /* Auto Increment Location Address Command */
 LCD_Command(0X0C);           /* Display ON Command                      */
 LCD_Command(0X01);           /* Clear Display Command                   */
 Delay_100us(30);
 Display(0x80,"ADC Result:"); /* Display string in the first line        */

 ADCON0 = 0x81;               /* Clock source=Fosc/32, channel-0, ADON=1 */
 ADCON1 = 0x80;               /* Result right justified                  */
 while(1)
 {
  ADGO   = 1;                   
  while(ADGO==1);             /* Wait until ADGO=0 (conversion completed)*/
  result = ADRESH;            /* Copy the 2 bit in ADRESH to result      */
  result = result << 8;       /* Shift it 8 bits to left                 */
  result = result + ADRESL;   /* Add left shifted value to 8 bit ADRESL  */

  for(k=0; k<=3; k++)         /* Convert the result in integer to ASCII  */
  {
   array[k] = result % 10;    /* Separate each digit of the integer      */
   result   = result / 10;
  }

  LCD_Command(0X8C);
  for(k=3; k>=0; k--)
  {
   LCD_Data(array[k]+'0');    /* Display the result on LCD               */
  }
 }
}

/*************************************************************************
* Function    : LCD_Command                                              *
*                                                                        *
* Description : Function to send a command to LCD                        *
*                                                                        *
* Parameters  : com - command to be sent                                 *
**************************************************************************/
void LCD_Command(int com)
{
 PORTD = com;                 /* Write the command to data lines         */
 RC0   = 0;                   /* RS-0(Command register)                  */
 RC1   = 1;                   /* E-1(Enable pin high)                    */
 Delay_us(30);                
 RC1   = 0;                   /* E-0(Enable pin low)                     */
}	

/*************************************************************************
* Function    : LCD_Data                                                 *
*                                                                        *
* Description : Function to display single character on LCD              *
*                                                                        *
* Parameters  : data - character to be displayed                         *
**************************************************************************/
void LCD_Data(int data)
{
 PORTD = data;                /* Write the character to data lines       */
 RC0   = 1;                   /* RS-1(Data register)                     */
 RC1   = 1;                   /* E-1(Enable pin high)                    */
 Delay_us(30);                  
 RC1   = 0;                   /* E-0(Enable pin low)                     */
}

/*************************************************************************
* Function    : Display                                                  *
*                                                                        *
* Description : Function to display string on LCD                        *
*                                                                        *
* Parameters  : loc - location                                           *
*               String to be displayed                                   *
**************************************************************************/
void Display(const char loc, const char *LCD)
{
 LCD_Command(loc);            /* Address of location to display string   */
 while(*LCD!='\0')            /* Check for termination character         */
 {	
  LCD_Data(*LCD);             /* Display the character on LCD            */
  LCD++;                      /* Increment the pointer                   */
 }
}

/*************************************************************************
* Function    : Delay_us                                                 *
*                                                                        *
* Description : Function for 1 microsecond delay                         *
*                                                                        *
* Parameter   : Delay - delay in microseconds                            *
**************************************************************************/
void Delay_us(char Delay)    
{		
 while((--Delay)!=0);	
}

/*************************************************************************
* Function    : Delay_100us                                              *
*                                                                        *
* Description : Function for delay                                       *
*                                                                        *
* Parameter   : Delay - delay interval                                   *
**************************************************************************/
void Delay_100us(unsigned long int Delay)
{
 Delay = Delay*15;
 while((--Delay)!=0);
}

/***************************  END OF PROGRAM  ****************************/

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/*************************************************************************

HEADER FILES

**************************************************************************/

#include<pic.h>

/*************************************************************************

FUNCTION DECLARATIONS

**************************************************************************/

void LCD_Command(int com);

void LCD_Data(int data);

void Display(const char Adr, const char *LCD);

void Delay_us(char Delay);

void Delay_100us(unsigned long int Delay);

/*************************************************************************

VARIABLE DECLARATIONS

**************************************************************************/

int k,result;

char array[5];

/*************************************************************************

MAIN FUNCTION

**************************************************************************/

void main()

{

TRISA = 0XFF; /* PORTA configured as i/p */

TRISC = 0X00; /* LCD control lines configured as o/p */

TRISD = 0X00; /* LCD data lines configured as o/p */

LCD_Command(0X30); /* LCD specification command */

Delay_us(35);

LCD_Command(0X30); /* LCD specification command */

Delay_us(35);

LCD_Command(0X30); /* LCD specification command */

Delay_us(35);

LCD_Command(0X38); /* Double Line Display Command */

LCD_Command(0X06); /* Auto Increment Location Address Command */

LCD_Command(0X0C); /* Display ON Command */

LCD_Command(0X01); /* Clear Display Command */

Delay_100us(30);

Display(0x80,"ADC Result:"); /* Display string in the first line */

ADCON0 = 0x81; /* Clock source=Fosc/32, channel-0, ADON=1 */

ADCON1 = 0x80; /* Result right justified */

while(1)

{

ADGO = 1;

while(ADGO==1); /* Wait until ADGO=0 (conversion completed)*/

result = ADRESH; /* Copy the 2 bit in ADRESH to result */

result = result << 8; /* Shift it 8 bits to left */

result = result + ADRESL; /* Add left shifted value to 8 bit ADRESL */

for(k=0; k<=3; k++) /* Convert the result in integer to ASCII */

{

array[k] = result % 10; /* Separate each digit of the integer */

result = result / 10;

}

LCD_Command(0X8C);

for(k=3; k>=0; k--)

{

LCD_Data(array[k]+'0'); /* Display the result on LCD */

}

/*************************************************************************

* Function : LCD_Command *

* *

* Description : Function to send a command to LCD *

* *

* Parameters : com - command to be sent *

**************************************************************************/

void LCD_Command(int com)

{

PORTD = com; /* Write the command to data lines */

RC0 = 0; /* RS-0(Command register) */

RC1 = 1; /* E-1(Enable pin high) */

Delay_us(30);

RC1 = 0; /* E-0(Enable pin low) */

}

/*************************************************************************

* Function : LCD_Data *

* *

* Description : Function to display single character on LCD *

* *

* Parameters : data - character to be displayed *

**************************************************************************/

void LCD_Data(int data)

{

PORTD = data; /* Write the character to data lines */

RC0 = 1; /* RS-1(Data register) */

RC1 = 1; /* E-1(Enable pin high) */

Delay_us(30);

RC1 = 0; /* E-0(Enable pin low) */

}

/*************************************************************************

* Function : Display *

* *

* Description : Function to display string on LCD *

* *

* Parameters : loc - location *

* String to be displayed *

**************************************************************************/

void Display(const char loc, const char *LCD)

{

LCD_Command(loc); /* Address of location to display string */

while(*LCD!='\0') /* Check for termination character */

{

LCD_Data(*LCD); /* Display the character on LCD */

LCD++; /* Increment the pointer */

}

/*************************************************************************

* Function : Delay_us *

* *

* Description : Function for 1 microsecond delay *

* *

* Parameter : Delay - delay in microseconds *

**************************************************************************/

void Delay_us(char Delay)

{

while((--Delay)!=0);

}

/*************************************************************************

* Function : Delay_100us *

* *

* Description : Function for delay *

* *

* Parameter : Delay - delay interval *

**************************************************************************/

void Delay_100us(unsigned long int Delay)

{

Delay = Delay*15;

while((--Delay)!=0);

}

/*************************** END OF PROGRAM ****************************/

Topics related to PIC16F877A Development Board-Mini

Resources

Softwares

Datasheets
- PIC 16F877A
- MCP9700
- MAX232
- CP2102
- LM7805
- LD1117
- LCD (16×2)

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chandru says:

April 24, 2016 at 6:17 pm

thanks you

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