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PIC16F1786 ADC issue

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bandi12

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Hello. I am trying to measure voltage with this PIC, it has a 12 bit ADC because i got wrong voltages displayed i tried to display the ADC reading values and i got a surprise.

At 0V ADC is 64660 and goes up to 65510 meaning 2.1V from then suddenly drops to 0 and starts counting up to 1230 meaning 5V.

I used MikroC for PIC build in functions for ADC:

Code: 
void main() {

C1ON_bit = 0;                       // Disable comparators
C2ON_bit = 0;

TRISA = 0x7;
ANSELA = 0x7;
InitLCD();
ADC_Init();

while(1) {

char txt[10];
unsigned int adcRead = ADC_Get_Sample(2);
WordToStrWithZeros(adcRead, txt);
LCD_Out(1,2,txt);
Delay_ms(500);
}

}
 

Hi,


Reference of your PIC ?
FOSC value ?
Where are LCD variables (config) init ?

better to put variable outside of the main !
Code: 
char txt[10];
unsigned int adcRead;

void main() 
{
C1ON_bit = 0;                       // Disable comparators
C2ON_bit = 0;

TRISA = 0x7;
ANSELA = 0x7;
InitLCD();
ADC_Init();

while(1)
 {
    adcRead = ADC_Get_Sample(2); 
    WordToStrWithZeros(adcRead, txt);
    LCD_Out(1,2,txt);
   Delay_ms(500);
 }
}


try to use MCU register instead of MikroC ADC lib ...
 

I don't posted the LCDInit() it's the standard init and a hello message ( they are in a different .h file)

I don't touched the ADC registers, until now ( with 10bit ADC) mikroC's ADC_Init() did all the configs, but this time i think it has some problems.

I will try to read the datasheet and found out how to use the ADC from registers ( i don't really worked with registers until now, i used the already made functions of mikroC).
 

hello,

i don't have this PIC to test this program , but must be like this..
i suppose reading Chanel RA0 in single end mode.



//see table page 169 of datasheet DS40001637C
Code: 
unsigned int Adc_measure;


void Init_ADC()
{
ADCON0.ADRMD=0;  // 12 bits mode
ADCON2.ADFM=1; // Result format 1= Right justified    
ADCON2.ACQT=1; // Acquisition time 7 = 20TAD 2 = 4TAD 1=2TAD    
ADCON2.ADCS=6; // Clock conversion bits 6= FOSC/64 2=FOSC/32    
 // Set external reference source    
ADCON1.ADPREF =0; //+ Vref = +Vdd    
 ADCON1.ADNREF = 0; // -Vref- =Vss    
 ADCON2.TRIGSEL = 0;  
//   negative is VSS  (single end measure) or select another chanel if differential
  ADCON2.CHS =0x0F; 
  ADCON0.ADON = 1; // Start ADC  
}  
 
unsigned int Get_ADC0()     // <- you can add channel as parameter !
{
unsigned int MSB,LSB;
unsigned int Result;
 ADCON0.GO=1; // And begin A/D conv.    
  while(ADCON0.DONE);    
  ADCON0.ADON = 0; // Stop ADC    
  MSB= ADRESH;
 LSB= ADRESL;   
 Result= MSB <<8 + LSB;
return Result;
}


void main()
{
.. init hardware ..
Init_ADC();
while(1)
{
Adc_measure=Get_ADC0();
.... display 
..
}
 

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