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ADC 16f877 from 8 to 10 bit

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maria258

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I have already done an 8 bit mode adc but would like to change it to 10 bit. How can this code be altered to make it a 10 bit?

thanks
maria

Code: 
#include<htc.h>

__CONFIG (0x3F72); //configured fuses
//define ports for easier reading
#define LEDS PORTB

void delay(unsigned char itime);

void main(void)
{
//8bit data-type variables
unsigned char x;	//ADC low byte
unsigned char y;	//ADC high byte
unsigned int z;	//final result

TRISB=0x00; //output
TRISA=0xFF;	//inputs
LEDS=0xFF;	//clear/switch off LEDS

while(1)
{
//ADFM=1, all i/ps analog, +VREF enabled
//Configure the functions of the Port bits
ADCON1=0b10000001;
//clock/channel select & enable bits
//controls the operation of the A/D module
ADCON0=0b11000001;


delay(1);
//Start a2d conversion
//Set GO bit (ADCON0=ADCON0|1;)
GODONE=1;
//wait end-of-conversion (conversion complete)
while(GODONE==1);
x=ADRESL; //store low byte
x=x>>1;	//shift 1 bit to the right
y=ADRESH;	//store high byte
y=y<<7;	//shift left 7 bit position
z=x|y; //combine together
LEDS=~z; //output on leds
}
}

void delay(unsigned char itime)
{
unsigned char i,j;
for(i=0;i<itime;i++)
for(j=0;j<1;j++);
}
 

Code: 
/*--- Initialise A/D convertor ---*/

void init_ad(void)
  {
  ADCON1 = 0x20U;   /* Conversion clock Fosc/32 */
  ADCON0 = 0x80U;   /* 10 bit Right justified result, Vdd as ref */    
  }
 
/*--- Read A/D conversion ---*/

int read_ad(unsigned char channel)
  {
  int result;
  unsigned char acquisition_time = 3U;

  ADCON0 = 0x01U;             /* Turn on A/D */
  ADCON0 |= (channel << 2U);  /* Select channel */ 
        
  while(acquisition_time--){ /* Sample channel */
    ;
    }
    
  GODONE = 1U;    /* Start conversion */
  
  while(GODONE){  /* Wait for conversion end */
    ;
    }
    
  result = ADRESH;
  result <<= 8U;
  result += ADRESL;
  return result;
  }
 

but the problem is since it is 10 bit and they are shown on leds, there will be another 2 leds that need to be shown on another port and dont know how to do that.
thanks
 

Code: 
#define LEDS_8 LATB
#define LEDS_2 LATC

/*--- Read A/D conversion ---*/

void read_ad(unsigned char channel)
  {
  unsigned char acquisition_time = 3U;

  ADCON0 = 0x01U;             /* Turn on A/D */
  ADCON0 |= (channel << 2U);  /* Select channel */ 
        
  while(acquisition_time--){ /* Sample channel */
    ;
    }
    
  GODONE = 1U;    /* Start conversion */
  
  while(GODONE){  /* Wait for conversion end */
    ;
    }
    

  LEDS_8 = ADRESL;

  LEDS_2 &= 0xfc;
  LEDS_2 |= ADRESH;
  }
 
Last edited:

Hi Sir btbass,
I am new in pic and I use 16F877A ,MPLAB and Hi-tech C compiler,
I read about ADC for one month plus & try those who master in this code but does not work for me. Especially ADGO or GODONE always give me compiler error.
---
undefined identifier "ADGO"--
Any advice form you Sir, Thanks a lot.

---------- Post added at 04:01 ---------- Previous post was at 03:52 ----------

Sorry still not finish,

I am using sharp sensor GP2d120 and I connect to RA1 pin as analog input.
Physically I can measure the voltage when I play around with object distance.
But soft code I still having problem how to get the ADC results.my flow is..

if object < 10cm, Red LED blink ( connect at RC5)
else if ( 10cm < object < 20cm) , Green LED blink (connect at RC6 )
else if Blue LED blink ( connect at RC7)

Look like very simple for outputs but how can I get the input from RA1??
Please kindly help to explain how can I write the code.Thanks.

---------- Post added at 04:07 ---------- Previous post was at 04:01 ----------

I did try with below code but does not work in hardware.my code start here-

#include <pic.h>

__CONFIG ( 0x3F32 );

#define PORTBIT(adr,bit) ((unsigned)(&adr)*8+(bit)) //no modify this line

static bit led @ PORTBIT(PORTC,5);


void timer1init(void)
{
/* initialisation of timer1; */

T1CKPS1=1; T1CKPS0=1; /* select prescaler by 8 */
T1OSCEN=0; /* secondary oscillator disabled */
T1SYNC=0;
TMR1CS=0; /* clock source - internal clock */
TMR1ON=1; /* enable timer 1 */
}

void delayus(unsigned char us)
{
for (;us--;);
}

void adcinit(void)
{
/* initialisation of AD converter */
TRISA = 0xFF; /* all pin of portA are inputs */
ADCON1 = 0x00; /* pin RA1 is analog input */
ADCON0 = 0x49; /* config the converter */
delayus(100);
}

void settimer1(unsigned int val)
{
TMR1ON=0;
TMR1IF=0;
TMR1L=val&0xFF;
TMR1H=val>>8;
TMR1ON=1;
}

unsigned int adcsample(void)
{

for (ADCON0|=0x04; ADCON0&0x04; ); /* start and wait for done */

return ADRESL|(ADRESH<<8);
}


void main(void)
{
unsigned int speed;

TRISC=0x00;
timer1init();
adcinit();

for(;;) {
speed=adcsample();
settimer1(speed);
for(;!TMR1IF;); /* wait for timer1 overflow */
led=!led;
}
}

//code end here
 

I can not see any problems with your code other than

ADCON1 = 0x00;

You need to set bit 7 to right justify the result otherwise the 6 Least Significant bits of ADRESL will always are read as 0.

ADCON1 = 0x80;
 
  • Like
Reactions: mncp

    M

    mncp

    Points: 2
    Helpful Answer Positive Rating
Hi Sir btbass,

I will change and tried.But my Blue , Red and Green LED all OFF.
Is there any things wrong with my value? I just want to measure the distance.
Please advice. Thanks.


/*============================================================================

INCLUDE

============================================================================*/
#include <pic.h>


/*============================================================================

Configuration Bits

============================================================================*/
__CONFIG ( 0x3F32 );


/*============================================================================

User definition

============================================================================*/
#define PORTBIT(adr,bit) ((unsigned)(&adr)*8+(bit)) //no modify this line

static bit ledR @ PORTBIT(PORTC,5);
static bit ledG @ PORTBIT(PORTC,6);
static bit ledB @ PORTBIT(PORTC,7);


/*============================================================================

Program

============================================================================*/

void timer1init(void)
{
/* initialisation of timer1; */

T1CKPS1=1; T1CKPS0=1; /* select prescaler by 8 */
T1OSCEN=0; /* secondary oscillator disabled */
T1SYNC=0;
TMR1CS=0; /* clock source - internal clock */
TMR1ON=1; /* enable timer 1 */
}

void delayus(unsigned char us)
{
for (;us--;);
}

void adcinit(void)
{
/* initialisation of AD converter */
TRISA = 0xE3; /* all pin of portA are inputs */
TRISC = 0X00;
ADCON1 = 0x08; /* pin RA1 is analog input */
ADCON0 = 0x49; /* config the converter */
ADON =1;
delayus(100);
}

void settimer1(unsigned int val)
{
TMR1ON=0;
TMR1IF=0;
TMR1L=val&0xFF;
TMR1H=val>>8;
TMR1ON=1;
}

unsigned int adcsample(void)
{

for (ADCON0|=0x04; ADCON0&0x04; ); /* start and wait for done */

return ADRESL|(ADRESH<<8);
}


void main(void)
{
unsigned int value;

TRISA=0xE3;
timer1init();
adcinit();

for(;;) {
value=adcsample();
settimer1(value);
for(;!TMR1IF;); /* wait for timer1 overflow */
if (value == 1)
{
ledG=1;
ledR=1;
ledB=1;

// delayus(100);
}
else {
ledR=0;
ledG=0;
ledB=0;
}
}
}


Clovis
 

if (value == 1)

It is very unlikely that the result will be exactly 1?

Try something like

if (value > 20)
 

Dear btbass,

Thanks for your advice. I tried all possible value 10 to 500 with different sign ( < or > ) but keep blinking Red LED. I do not know what wrongs. I will try to study how to convert analog Voltage to mm/cm (may be there got maths formula) and will let you know and discuss again. Anyway thanks sir.
"""""""
if (value>20)
{
ledR=!ledR;
ledG=0;
ledB=0;
}
//else if ( value < 30)
// {
// ledG=!ledG;
// ledR=0;
// ledB=0;
// }
else
{
// ledB=!ledB;
ledR=0;
// ledG=0;
}
""""""""

Clovis
 

Hi btbass,

I just try with this code , but LED blink alternatively instead of on one only9in terms of distance) although I did not place any object in fornt of sensor.Any advice Sir?
Thanks.
Clovis

---------- Post added at 07:30 ---------- Previous post was at 07:29 ----------

void main(void)
{
unsigned int value;

TRISC=0x00;
timer1init();
adcinit();

for(;;) {
value=adcsample();
settimer1(value);
for(;!TMR1IF;); /* wait for timer1 overflow */
if(value>=200){
ledR=!ledR;
}
else if(value>=400){
ledG=!ledG;
}
else if(value>=600){
ledB=!ledB;
}

}
}
 

This code won't work, it will never get to the last two else if's .

Code: 
if(value>=200){
  ledR=!ledR;
  }
else if(value>=400){
  ledG=!ledG;
  }
else if(value>=600){
  ledB=!ledB;
  }

You could try

Code: 
if((value >= 200) && (value < 400)){
  ledR=!ledR;
  }
else if((value >= 400) && (value < 600)){
  ledG=!ledG;
  }
else if(value >= 600){
  ledB=!ledB;
  }
 

Thanks Sir,I will try it. BTW, i read from this Linearizing Sharp Ranger Data about sharp sensor calculation. R = (2914 / (V + 5)) - 1
But another formula is R = (2194 / (V + 5)) - 1
I do not know which cal data is right. Anyway , I did calculation for 3 V, 2 V and 1V. 3V=313 .., 2v=365 and 1v=438.(base on 2194) and
3V=363 .., 2v=415 and 1v=485.(base on 2914). I try all range.Will get back to you. Thanks.
Clovis

---------- Post added at 02:51 ---------- Previous post was at 01:11 ----------

Hi btbass,

I have tried a lot of code(change here and there for the value),it does not work for me. My programming skill ???? But I did try with blinking LED speed with one LED. It works very good.

I attached the code below. Any idea about how can I change to 3 different LED to output signal depending on distance(voltage)?
Please kindly advice. Thanks in advanced..

#include <pic.h>


/*============================================================================

Configuration Bits

============================================================================*/

__CONFIG ( 0x3F32 );

/*============================================================================

User definition

============================================================================*/
#define PORTBIT(adr,bit) ((unsigned)(&adr)*8+(bit)) //no modify this line

//static bit led @ PORTBIT(PORTC,5);

static bit ledR @ PORTBIT(PORTC,5);
static bit ledG @ PORTBIT(PORTC,6);
static bit ledB @ PORTBIT(PORTC,7);

/*============================================================================

Program

============================================================================*/

void timer1init(void)
{
/* initialisation of timer1; */

T1CKPS1=1; T1CKPS0=1; /* select prescaler by 8 */
T1OSCEN=0; /* secondary oscillator disabled */
T1SYNC=0;
TMR1CS=0; /* clock source - internal clock */
TMR1ON=1; /* enable timer 1 */
}

void delayus(unsigned char us)
{
for (;us--;);
}

void adcinit(void)
{
/* initialisation of AD converter */
TRISA = 0xFF; /* all pin of portA are inputs */
ADCON1 = 0x00; /* pin RA1 is analog input */
ADCON0 = 0x49; /* config the converter */
delayus(100);
}

void settimer1(unsigned int val)
{
TMR1ON=0;
TMR1IF=0;
TMR1L=val&0xFF;
TMR1H=val>>8;
TMR1ON=1;
}

unsigned int adcsample(void)
{

for (ADCON0|=0x04; ADCON0&0x04; ); /* start and wait for done */

return ADRESL|(ADRESH<<8);
}


void main(void)
{
unsigned int blink_speed;

TRISC=0x00;
timer1init();
adcinit();

for(;;) {
blink_speed=adcsample();
settimer1(blink_speed);
for(;!TMR1IF;); /* wait for timer1 overflow */
ledG=!ledG; //nearer blinking speed faster
}
}
//********** Build successful! **********


Clovis.
 

attached my circuit diagram
 

Attachments

  • My_Circuit.zip
    29.9 KB · Views: 103

Hi sir ,
I attached my circuit n the code below. Any idea about how can I change to 3 different LED to output signal depending on distance(voltage)?
Please kindly advice. Thanks in advanced..
 

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