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Problem with adc in 18F458

 
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ADC_18F458
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Problem with adc in 18F458
PostPosted: Mon May 23, 2005 9:15 pm     Reply with quote
I am using five adc channels in a pic18F458 and I use for testing ANO and the others connected to ground (AN1, AN2, AN3, AN4) and I get a lot of garbage in Hyperterminal:

Code:

  0,  0,  0, 64,  0
  0,  0,  0,  0, 64
  0,  0, 64,  0,  0
  0,  0,  0,  0,  0
  0,  0,  0,  0, 64
  0,  0, 64,  0,  0
 64,  0, 64,  0,  0
  0,  0, 64,  0,  0
  0,  0,  0,  0,  0
 64,  0, 64,  0,  0
  0,  0,  0,  0,  0
 64,  0,  0,  0,  0
  0,  0,  0,  0,  0
 64,  0, 64,  0,  0
 64,  0,  0,  0, 64
 64,  0, 64, 64,  0
 64,  0, 64, 64,  0
128,  0,  0,  0,  0
 64,  0, 64, 64,  0
  0, 64, 64, 64,  0
 64,  0, 64, 64,  0
128, 64,  0,  0, 64
  0,  0,  0,  0,  0
  0,  0,  0, 64,  0
 64,  0,  0,  0,  0


Here is only working AN0, and the others are connected to ground

Code:

#if defined(__PCH__)
#include <18F458.h>
#device ADC=16
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=10000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#endif

void main() {

   int ch0,ch1,ch2,ch3,ch4;
   char coma;

   setup_port_a( ALL_ANALOG );
   setup_adc( ADC_CLOCK_INTERNAL );
   coma = ',';
   

   while (TRUE)
       {
         set_adc_channel(0);
         delay_us(10);
         ch0 = Read_ADC();
         printf("%3U%C",ch0,coma);
         delay_ms(10);
         set_adc_channel(1);
         delay_us(10);
         ch1 = Read_ADC();
         printf("%3U%C",ch1,coma);
         delay_ms(10);
         set_adc_channel(2);
         delay_us(10);
         ch2 = Read_ADC();
         printf("%3U%C",ch2,coma);
         delay_ms(10);
         set_adc_channel(3);
         delay_us(10);
         ch3 = Read_ADC();
         printf("%3U%C",ch3,coma);
         delay_ms(10);
         set_adc_channel(4);
         delay_us(10);
         ch4 = Read_ADC();
         printf("%3U\r\n",ch4);
         delay_ms(10);
       }
}


Thanks for your help!!!
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Mon May 23, 2005 10:01 pm     Reply with quote
Make the changes shown in bold below:
Quote:
#include <18F458.h>
#device ADC=10
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=10000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
#endif

void main() {

int16 ch0,ch1,ch2,ch3,ch4;
char coma;

setup_port_a( ALL_ANALOG );
setup_adc(ADC_CLOCK_DIV_16);
coma = ',';


while (TRUE)
{
set_adc_channel(0);
delay_us(10);
ch0 = Read_ADC();
printf("%LU%C",ch0,coma);
delay_ms(10);
set_adc_channel(1);
delay_us(10);
ch1 = Read_ADC();
printf("%LU%C",ch1,coma);
delay_ms(10);
set_adc_channel(2);
delay_us(10);
ch2 = Read_ADC();
printf("%LU%C",ch2,coma);
delay_ms(10);
set_adc_channel(3);
delay_us(10);
ch3 = Read_ADC();
printf("%LU%C",ch3,coma);
delay_ms(10);
set_adc_channel(4);
delay_us(10);
ch4 = Read_ADC();
printf("%LU\r\n",ch4);
delay_ms(10);
}
}
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