Unable to get 10-bit ADC to work on PIC16F877 - HELP

[cxiong]

I am writting code to do 10-bit ADC on the '877 and it does not do the job. It only do 8-bit (255) inteads of 10-bit (1024). I know that it does not do the job because instead of reading the LED pattern on PortD, I feed it through the RS 232, and use the Hyperterminal to read the max & min.

Please Help:

Here is my code. What did I do wrong?

=========================================
#include <16F877.h>
#fuses XT,NOWDT,NOPUT,NOBROWNOUT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7)
#use fast_io(d)
#bit ADFM_BIT=0X9F.7
// Inhale variables
#define KDI = 0;
#define KII = 0.001;
#define KPI = 1.0;
// Exhale variables
#define KDE = 0;
#define KIE = 0.001;
#define KPE = 1.0;



// ADC to long because it is 10-bit
typedef long uint16;
uint16 adc_result = 0;
//void adc_result( long int data )
int i,min,max;


main()
{
set_tris_a(0x3f); //set port a as input
set_tris_b(0x00); //set port b as output -- > inhale motor
set_tris_c(0x00); //set port c as output -- > exhale motor
set_tris_d(0x00); //set port d as output -- > ADC test pattern

setup_port_a( ALL_ANALOG );
//RA0 Analog pin
setup_adc( ADC_CLOCK_DIV_8 );
set_adc_channel( 0 );
ADFM_BIT=0;
delay_ms(10); // delay 10 mSec.
do
{ //take sample 30 and display min & max
min=1024;
max=0;
for (i=0; i<30; ++i)
{
delay_ms(100);
adc_result = read_adc();
output_d(adc_result);
if(adc_result min=adc_result;
if(adc_result>max);
max=adc_result;
}
printf("\n\rMin: \%4x MAX: \%4x",min,max);

}
while (1);
}
====================================================
___________________________
This message was ported from CCS's old forum
Original Post ID: 144516256

[PCM programmer]

:=I am writting code to do 10-bit ADC on the '877 and it does not do the job. It only do 8-bit (255) inteads of 10-bit (1024). I know that it does not do the job because instead of reading the LED pattern on PortD, I feed it through the RS 232, and use the Hyperterminal to read the max & min.

But your "min" and "max" variables are only 8 bit values.
They cannot hold a 10-bit number.

:=
:=Please Help:
:=
:=Here is my code. What did I do wrong?
:=
:==========================================
:=#include <16F877.h>
:=#fuses XT,NOWDT,NOPUT,NOBROWNOUT,NOPROTECT,NOLVP
:=#use delay(clock=4000000)
:=#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7)
:=#use fast_io(d)
:=#bit ADFM_BIT=0X9F.7
:=// Inhale variables
:=#define KDI = 0;
:=#define KII = 0.001;
:=#define KPI = 1.0;
:=// Exhale variables
:=#define KDE = 0;
:=#define KIE = 0.001;
:=#define KPE = 1.0;
:=
:=
:=
:=// ADC to long because it is 10-bit
:=typedef long uint16;
:=uint16 adc_result = 0;
:=//void adc_result( long int data )

Remember that in CCS, an "int" is only 8 bits.
You should change these variables to be int16.

:=int i,min,max;
:=
:=
:=main()
:={
:= set_tris_a(0x3f); //set port a as input
:= set_tris_b(0x00); //set port b as output -- > inhale motor
:= set_tris_c(0x00); //set port c as output -- > exhale motor
:= set_tris_d(0x00); //set port d as output -- > ADC test pattern
:=
:= setup_port_a( ALL_ANALOG );
:= //RA0 Analog pin
:= setup_adc( ADC_CLOCK_DIV_8 );
:= set_adc_channel( 0 );
:= ADFM_BIT=0;
:= delay_ms(10); // delay 10 mSec.
:= do
:= { //take sample 30 and display min & max
:= min=1024;
:= max=0;
:= for (i=0; i<30; ++i)
:= {
:= delay_ms(100);
:= adc_result = read_adc();
:= output_d(adc_result);
:= if(adc_result
Here, you are putting a 16-bit word into an 8-bit variable.
:= min=adc_result;
:= if(adc_result>max);

Also, here:
:= max=adc_result;
:= }

You will also need to change this statement, so
it uses \%lx, to display the "long" (16-bit) values.
:= printf("\n\rMin: \%4x MAX: \%4x",min,max);
:=
:= }
:= while (1);
:=}
:=====================================================
___________________________
This message was ported from CCS's old forum
Original Post ID: 144516257

[Kenny]

:=I am writting code to do 10-bit ADC on the '877 and it does not do the job. It only do 8-bit (255) inteads of 10-bit (1024). I know that it does not do the job because instead of reading the LED pattern on PortD, I feed it through the RS 232, and use the Hyperterminal to read the max & min.
:=
:=Please Help:
:=
:=Here is my code. What did I do wrong?
:=
:==========================================
:=#include <16F877.h>
:=#fuses XT,NOWDT,NOPUT,NOBROWNOUT,NOPROTECT,NOLVP
:=#use delay(clock=4000000)
:=#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7)
:=#use fast_io(d)
:=#bit ADFM_BIT=0X9F.7
:=// Inhale variables
:=#define KDI = 0;
:=#define KII = 0.001;
:=#define KPI = 1.0;
:=// Exhale variables
:=#define KDE = 0;
:=#define KIE = 0.001;
:=#define KPE = 1.0;
:=
:=
:=
:=// ADC to long because it is 10-bit
:=typedef long uint16;
:=uint16 adc_result = 0;
:=//void adc_result( long int data )
:=int i,min,max;
:=
:=
:=main()
:={
:= set_tris_a(0x3f); //set port a as input
:= set_tris_b(0x00); //set port b as output -- > inhale motor
:= set_tris_c(0x00); //set port c as output -- > exhale motor
:= set_tris_d(0x00); //set port d as output -- > ADC test pattern
:=
:= setup_port_a( ALL_ANALOG );
:= //RA0 Analog pin
:= setup_adc( ADC_CLOCK_DIV_8 );
:= set_adc_channel( 0 );
:= ADFM_BIT=0;
:= delay_ms(10); // delay 10 mSec.
:= do
:= { //take sample 30 and display min & max
:= min=1024;
:= max=0;
:= for (i=0; i<30; ++i)
:= {
:= delay_ms(100);
:= adc_result = read_adc();
:= output_d(adc_result);
:= if(adc_result := min=adc_result;
:= if(adc_result>max);
:= max=adc_result;
:= }
:= printf("\n\rMin: \%4x MAX: \%4x",min,max);
:=
:= }
:= while (1);
:=}
:=====================================================


Another possible problem is that you need to have the following line in 16F877.h to do 10 bit A/D

#device PIC16F877 ADC=10

Regards
Kenny
___________________________
This message was ported from CCS's old forum
Original Post ID: 144516269