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AD7714

 
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bloureiro



Joined: 26 Feb 2007
Posts: 6

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AD7714
PostPosted: Thu Oct 04, 2007 8:43 am     Reply with quote

Hi make this driver for a multi-channel acquisitions and works fine.



Code:

//*************************************************************
// Routines for AD7714
// write_adc_byte()
// adc_init()
// read_adc_word()
// read_adc_value()
//*************************************************************

//configure PIC ports
#define ADC_DRDY  PIN_B1
#define ADC_DO    PIN_B2
#define ADC_DI    PIN_B3
#define ADC_RESET PIN_B4
#define ADC_CS    PIN_B5
#define ADC_CLK   PIN_B0

void write_adc_byte(int data)
{
   int i;
   output_low(ADC_CS);
   for(i=1;i<=8;++i)
   {
      output_low(ADC_CLK);
      output_bit(ADC_DI, shift_left(&data,1,0));
      output_high(ADC_CLK);
   }
   output_high(ADC_CS);
}

void adc_init(int8 filterH,int8 filterL)
{
   output_low(ADC_RESET);
   output_high(ADC_CLK);
   output_high(ADC_CS);       //Set high to AD7714 chip select low pin
   output_high(ADC_RESET);    //Set high to AD7714 reset low pin
   delay_ms(1000);
   write_adc_byte(0x27);      //to com register, channel & filter Hi  antes 24--------27 datasheet
   write_adc_byte(filterH);   //to filter hi register  0xCF  ------------------------ 4F datasheet
   write_adc_byte(0x37);      //to com.register, channel & filter low  antes 30-------37 datasheet
   write_adc_byte(filterL);   //to filter low register  00 antes----------------------A0 datasheet
   
 
   write_adc_byte(0x10);         //to com register, channel & mod register
   write_adc_byte(0x20);         //to mod register, self test
   while ( !input(ADC_DRDY) );
   while ( input(ADC_DRDY) );
   write_adc_byte(0x11);         //to com register, channel & mod register
   write_adc_byte(0x20);         //to mod register, self test
   while ( !input(ADC_DRDY) );
   while ( input(ADC_DRDY) );
   write_adc_byte(0x12);         //to com register, channel & mod register
   write_adc_byte(0x20);         //to mod register, self test
   while ( !input(ADC_DRDY) );
   while ( input(ADC_DRDY) );
}



int32 read_adc_word()
{
   int i;
   int32 data;
   output_low(ADC_CS);
   for(i=1;i<=24;++i)
   {
      output_low(ADC_CLK);
      output_high(ADC_CLK);
      shift_left(&data,3,input(ADC_DO));
   }
   output_high(ADC_CS);
   return data;
}



int32 read_adc_value(int canal)
{
   int32 value;
   
   switch(canal)
   {
      case 1:
      write_adc_byte(0x58);         
      break;

      case 2:
      write_adc_byte(0x59);         
      break;

      case 3:
      write_adc_byte(0x5A);break;

      case 4:
      write_adc_byte(0x5B);break;

      case 5:
      write_adc_byte(0x5E);break;
   }
   
   while ( !input(ADC_DRDY) );
   while ( input(ADC_DRDY) );
   
   value=read_adc_word();

   return value;
}

float convert_to_volts(int32 temp){
   return (float)temp*0.0000000745;//ref 1,25V
}




To chose the sampling frequency you will need write the registers of filter
in the adc_init(int8 filterH,int8 filterL).
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