ADC of Xc167

 ADC of Xc167

Hello

Port 5 is not responding.
I have set the compatibility mode for regiseter.
at P5.6 and P5.8 is a voltage of 2.5 V created
I read from P5.6 and P5.8 a voltage.
The function does not work as I expect.
I expect to P5.6 ADC_DAT = 0x63FF read at 5V
or ADC_DAT = 0x6000 at 0V
But, I get at 5V or 0V the same result ADC_DAT = 0x6202
And I dont know how I read the voltage from the P5.6 or P5.8
I must set other register when I chose compatibilty mode ??

Thanks for Your Help

#include <xc167.h>
#include <intrins.h>
#include <XC16X.h>


void init ();
int AD_Strom_messung (int kanal);

unsigned int Strom_Wert,Strom1,Strom2;
int kanal;
.
.
.

void main (){      {
init ();
.
.
.
while(1)
 {
Strom2 = AD_Strom_messung (6); // read P5.6 ====> 15F
Strom1 = AD_Strom_messung (8); // read der P5.5 ====> 15E

}//end of while
}//end of main
.
.
int AD_Strom_messung (int kanal){

 ADC_CON = kanal + 0x0080 ;      // Select Channel und start Conversion


 do {

 }while (ADC_CON & 0x0100);// wait of end Conversion
Strom_Wert = ADC_DAT & 1023 ;//read ADRES of ADC_DAT
return Strom_Wert;
 }


void init ()
   {
ADC_CON1 = 0x0104 ;
P5DIDIS  = 0xFFFF ;
   }

 RE: ADC of Xc167

Perhaps you are running into this issue that is described as a hint in the errata sheet.

ADC_X.H1 Polling of Bit ADBSY
After an A/D conversion is started (standard conversion by setting bit ADST = 1, injected conversion by setting ADCRQ = 1), flag ADBSY is set 5 clock cycles later. When polling for the end of a conversion, it is therefore recommended to check e.g. the interrupt request flags ADC_CIC_IR (for standard conversions) or ADC_EIC_IR (for injected conversions) instead of ADBSY.

Perhaps you could change your code to something like this and see if you have the same result?

#include <xc167.h>

unsigned int Strom_Wert;
unsigned int Strom1;
unsigned int Strom2;

void init () {
  ADC_CON1 = 0x0104 ;
  P5DIDIS  = 0xFFFF ;
}

int AD_Strom_messung (int kanal){
  ADC_CIC_IR = 0;
  ADC_CON = kanal + 0x0080 ;    // Select Channel und start Conversion

  do {
  }while (ADC_CIC_IR == 0);     // wait of end Conversion
  Strom_Wert = ADC_DAT & 1023;  // read ADRES of ADC_DAT
  return Strom_Wert;
 }

void main(void) {
  init();

  while(1)
  {
    Strom2 = AD_Strom_messung (6); // read P5.6 ====> 15F
    Strom1 = AD_Strom_messung (8); // read der P5.5 ====> 15E
  }//end of while
}//end of main

 RE: ADC of Xc167

Thank you for your quick response
I've changed my code and I have
P5.6 to a voltage applied 3v
and P5.8 nothing
I still get:
Strom1 = 0x02AA
Strom2 = 0x0292

this is not correct
what could be the reason !!!!!

int AD_Strom_messung (int kanal){
  ADC_CIC_IR = 0;
  ADC_CON = kanal + 0x0080 ;    // Select Channel und start Conversion

  do {
  }while (ADC_CIC_IR == 0);     // wait of end Conversion
  Strom_Wert = ADC_DAT & 1023;  // read ADRES of ADC_DAT
  return Strom_Wert;
 }

void main(void) {
  init();

  while(1)
  {
    Strom2 = AD_Strom_messung (6); // read P5.6 ====> 15F
    Strom1 = AD_Strom_messung (8); // read der P5.5 ====> 15E
  }//end of while
}//end of main

 RE: ADC of Xc167

Not sure.

If the ADC is working for one channel but not the other then chances are that it is not the ADC setup.

When you perform the conversion on channel 8 do you see 8 in the upper nibble of the ADC_DAT register indicating that the converter did indeed convert this channel? Are you sure you are on channel 8's input of the device and its connection is good? If the input of the ADC channel 8 is open (not connected) you should get a result around 2.5V (since the ADC charges the internal sample capacitor to half the voltage before a conversion is performed).

Strom1 = 0x02AA = 3.333V
Strom2 = 0x0292 = 3.216V

 RE: ADC of Xc167

hello
what do you mean about (is not the ADC setup !!!)
yes when i debug .,i see 8 in the upper nibble or 6 .
i have cheked the connection .its good
the Problem is
i change the voltage (0V.......4,5V) in P5.8 or P5.6
und i got same Result .
hier is what i see in debugg with voltage und without

ADC_CON    =   0x0006
ADC_CON1   =   0x0104
ADC_DAT    =   0x6292
Strom1     =   0x0292
Strom2     =   0x0295
Strom_Wert =   0x0292
ADC_CIC    =   0x0080

thanks for your help