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ADC on 16f690 using CCS

 
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brianm



Joined: 08 Mar 2008
Posts: 17

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ADC on 16f690 using CCS
PostPosted: Wed Oct 15, 2008 9:31 am     Reply with quote
I am using the following code to read 3 temperature sensors attached to a 16F690 .... I use 3 of the ADCs at a0, a1, a2.

Now my problem is that I have tried to use b4 and b5 and I get very erratic reading from those pins....same program just changing the read ADC ports.

Is there something special about the b4 & b5 pins that my code doesn't take into account or maybe my code is not taking something into account period.

Any thoughts

Thanks
Code:

//   version1.01
//
#include <16F690.h>
#device adc=10
#fuses INTRC_IO, NOWDT, BROWNOUT, PUT , NOMCLR
#use delay(clock=4000000)
#use rs232(baud=4800, xmit=PIN_B7, rcv=PIN_B6)


#include <MATH.H>
#include <stdlib.h>
 
#define pc3 pin_c3
#define pc0 pin_c0

int digit1;
int digit2;
int digit3;
int digit4;
int i;
int y;
int adcchannel;

int rem2;
int rem3;
long rem4;

int var1;
int var2;
int var3;
int var4[12];
long value;
long min;
long max;
//long avg;
long tavg;
long tvalue;
//long adc;
float voltage;
float temperature;
int abstemp;
long absroundtemp;
long ivoltage;
//===============================
void main() {
//setup_comparator(NC_NC_NC_NC);

output_c(0);

var1 = 0;
var2 = 3;
var3 = var1 / var2;

// common anode
//
// segment      pin
// -------      ---
//    a         rc0
//    b         rc1
//    c         rc2
// etc
//    g         rc6
//
// var4 is the decimal equivalent output for the numbers 0 thru 9
//
var4[0] = 64;  /* 1000000 */
var4[1] = 249; /* 1111001 */
var4[2] = 36;  /* 0100100 */
var4[3] = 48;  /* 0110000 */
var4[4] = 25;  /* 0011001 */
var4[5] = 18;  /* 0010010 */
var4[6] = 2;   /* 0000010 */
var4[7] = 120; /* 1111000 */
var4[8] = 0;   /* 0000000 */
var4[9] = 16;  /* 0010000 */
var4[10] = 63; /* 0111111 */


 setup_adc(adc_clock_internal);
 
 setup_adc_ports(sAN0|sAN1|sAN2);
 
//===========================================
while (true){

for(y=1; y<=3; ++y) {
//printf("   For  y = ");
//printf(" %u",y);
//printf("\n\r");
if (y<=1)
adcchannel = 2; // pin a2
if (y==2)
adcchannel = 0;  // pin a0
if (y==3)
adcchannel = 1;  // pin a1

 set_adc_channel(adcchannel);
 delay_us(20);
 //adc = read_adc();
//===================================
//do {
      min=0xffff;
      max=0;
tvalue = 0;
      for(i=0; i<=29; ++i) {
         delay_ms(100);
         value = read_adc();
tvalue=tvalue+value;
//printf(" %5Lu",value);
         if(value<min)
            min=value;
         if(value>max)
            max=value;
      }
tavg = tvalue/30.0;
value=tavg;
//      printf("\n\r Average adc reading is %4Lu",avg);
//     printf("\n\r Total: %5Lu  Average: %5Lu",tvalue,tavg);
//      printf("  Min: %4Lu  Max: %4Lu",min,max);

   


//===================================
voltage = (tavg/1023.0)*(500.0)/100.0;
//voltage = 213.4533434343;
temperature = (voltage-2.73)*100;

//printf("BEFORE ROUNDING Temperature is : ");
//printf("%4.1f",temperature);
//printf(" C\n\r");

abstemp = abs(temperature);

//printf("ABS Temperature is : ");
//printf("%u",abstemp);
//printf(" C\n\r");

//now round the temperature to the nearest integer
if((temperature-abstemp) > 0.5)
   {
          temperature=ceil(temperature);                 
   }       
   else
   {
        temperature=floor(temperature);
     }

absroundtemp = abs(temperature);

//printf(" Temperature is : ");
printf("%Ld",absroundtemp);
printf(" ");
//printf("   y= ");
//printf("%u",y);
if (y == 3)
printf("\n\r");

ivoltage = voltage;
//value = adc;
//value = ivoltage;
//value = 987;

digit4 = absroundtemp/1000;
rem4 = absroundtemp-(digit4*1000);


//rem4 = 654;
digit3 = rem4/100;
rem3 = rem4 -(digit3*100);

digit2 = rem3/10;
rem2 = rem3 -(digit2*10);

digit1 = rem2;

//digit4=0;
//digit3=8;
//digit2=7;
//digit1=6;

//printf("\n\rADC Value:");
//printf("%4Lu",tavg);

//printf("   Voltage:");
//printf("%4.3f",voltage);

//printf("   Temperature is : ");
//printf("%4.1f",temperature);
//printf(" C\n\r");


output_high(pin_b5);
 output_c(var4[y]);
delay_ms(1000);
output_low(pin_b5);
//   output_high(pin_a5);
//output_c(var4[y]);
//   output_c(var4[9]);
//delay_ms(10);
//output_low(pin_a5);
//output_c(0x00);  // All pins low

   delay_ms(500);

   
for(i=0; i<=50; ++i) {
if (digit4 != 0.0)
   {output_high(pin_b5);
   output_c(var4[digit4]);
   delay_ms(10);}
else
{};


   if (digit3 != 0.0)
      {output_high(pin_b5);
      output_c(var4[digit3]);
      delay_ms(10);
      output_low(pin_b5);}
   else
   {};
   

output_high(pin_a4);
output_c(var4[digit2]);
delay_ms(10);
output_low(pin_a4);


output_high(pin_a5);
output_c(var4[digit1]);
delay_ms(10);
output_low(pin_a5);
}

   var1 ++;
   if (var1 == 10){
   var1 = 0;
   }
//} while (TRUE);
}
} //for the y loop
}
ECACE



Joined: 24 Jul 2006
Posts: 94

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PostPosted: Wed Oct 15, 2008 12:39 pm     Reply with quote
Looking at your code...you are touching b5, this will throw off your A/D readings. See below:

Code:
output_high(pin_b5);
 output_c(var4[y]);
delay_ms(1000);
output_low(pin_b5);


You do this a couple times in your code. I would guess this is causing some of your problems.
_________________
A HW Engineer 'trying' to do SW !!! Run!!!
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Oct 15, 2008 12:48 pm     Reply with quote
Quote:
....same program just changing the read ADC ports.

Your setup_adc_ports() and set_adc_channel() code will also affect
the ability to make channels sAN10 and sAN11 work (pins B4 and B5).

As a general rule, post the code that fails. Don't post the good code
that doesn't fail. We need to see the bad code in order to recommend
how to fix it.


Also, use symbolic names for your pins. It's much easier to revise your
program if you do this. Example:
Code:

#define RED_LED  PIN_B5   


void main()
{

output_high(RED_LED);
delay_ms(500);
output_low(RED_LED);

while(1);
}


With this code, if you want to change the pin for the Red LED, you only
need to edit one line at the top of your program, instead of doing tedious
and error-prone edits all over the program. For example, if you want
to move the LED to pin C0, you just do this:
Code:
#define RED_LED   PIN_C0   
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