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ADUC7020: ADC in mode of continuous software conversation

Question asked by Jul511 on Oct 6, 2010

I need to digitize analog signals from sensors with maximum rating. But the output data i get is incorrect: meanings are decreasing while input signal is constant. I use the following configuration of ADC and core frequency:

     1) POWCON = 0x00

     2) ADCCON = 0x3A4 (16 clocks, max f, continuous software conversation)

     3) internal Vref=2,5 (REFCON = 0x01)

As input chanels ADC 0,1,2,3,4,12,13 are used. The code is:


ADCCP = chanel;    
ADCCON = 0x3A4;

     for (i=0;i<128;i++)

while (!ADCSTA);

ADCdata[i] = (ADCDAT>>16)&0xfff;


ADCCON = 0x324;

The result is: ADCdata[0] = 2055 ... ADCdata[127] = 2042. Real input signal corresponds to ADCdata[0].

How can I get the correct digital signal?