38.3.3 Selecting the Format of the ADC Result

• The integer or fractional data format selection is specified globally for all analog inputs using the Fractional Data Output Format bit, FRACT (ADCCON1[23]).
• The signed or unsigned data format selection can be independently specified for each individual analog input using the SIGNx bits in the ADCIMCONx registers

  .

int main(int argc, char** argv) {
int result[3];

/* Configure ADCCON1 */
ADCCON1bits.FRACT = 1;    // use Fractional output format ADCCON1bits.SELRES = 3;   // ADC resolution is 12 bits ADCCON1bits.STRGSRC = 0;  // No scan trigger.

/* Configure ADCCON2 */
ADCCON2bits.SAMC = 5;         // ADC sampling time = 5 * TAD7
ADCCON2bits.ADCDIV = 1;       // ADC clock freq is half of control clock = TAD7

/* Initialize warm up time register */ ADCANCON = 0;
ADCANCONbits.WKUPCLKCNT = 5;  // Wakeup exponent = 32 * TADx

/* Clock setting */ ADCCON3 = 0;
ADCCON3bits.ADCSEL = 0;       // Select input clock source
ADCCON3bits.CONCLKDIV = 1;    // Control clock frequency is half of input clock
ADCCON3bits.VREFSEL = 0;      // Select AVDD and AVSS as reference source

/* No selection for dedicated ADC modules, no presync trigger, not sync sampling */ ADCTRGMODEbits = 0;

/* Select ADC input mode */
ADCIMCON1bits.SIGN7 = 0;  // unsigned data format ADCIMCON1bits.DIFF7 = 0;  // Single ended mode ADCIMCON1bits.SIGN8 = 0;  // unsigned data format ADCIMCON1bits.DIFF8 = 0;  // Single ended mode ADCIMCON1bits.SIGN9 = 0;  // unsigned data format ADCIMCON1bits.DIFF9 = 0;  // Single ended mode

/* Configure ADCGIRQENx */
ADCGIRQEN1 = 0;           // No interrupts are used
ADCGIRQEN2 = 0;

/* Configure ADCCSSx */
ADCCSS1 = 0;              // No scanning is used
ADCCSS2 = 0;

/* Configure ADCCMPCONx */
ADCCMPCON1 = 0;           // No digital comparators are used. Setting the ADCCMPCONx ADCCMPCON2 = 0;           // register to '0' ensures that the comparator is disabled. ADCCMPCON3 = 0;           // Other registers are “don't care”.
ADCCMPCON4 = 0;
ADCCMPCON5 = 0; ADCCMPCON6 = 0;

/* Configure ADCFLTRx */
ADCFLTR1 = 0;             // No oversampling filters are used. ADCFLTR2 = 0;
ADCFLTR3 = 0; ADCFLTR4 = 0; ADCFLTR5 = 0; ADCFLTR6 = 0;
/* Set up the trigger sources */
ADCTRGSNSbits.LVL7 = 0;   // Edge trigger ADCTRGSNSbits.LVL8 = 0;   // Edge trigger ADCTRGSNSbits.LVL9 = 0;   // Edge trigger
ADC1TRG2bits.TRGSRC7 = 1; // Set AN7 to trigger from software
ADC2TRG3bits.TRGSRC8 = 1; // Set AN8 to trigger from software
ADC2TRG3bits.TRGSRC9 = 1; // Set AN9 to trigger from software 
/* Early interrupt */
ADCEIEN1 = 0;                // No early interrupt
ADCEIEN2 = 0;

/* Turn the ADC on */ ADCCON1bits.ON = 1;

/* Wait for voltage reference to be stable */
while(!ADCCON2bits.BGVRRDY); // Wait until the reference voltage is ready while(ADCCON2bits.REFFLT);   // Wait if there is a fault with the reference voltage

/* Enable clock to analog circuit */
ADCANCONbits.ANEN7 = 1;       // Enable the clock to analog bias

/* Wait for ADC to be ready */
while(!ADCANCONbits.WKRDY7); // Wait until ADC7 is ready

/* Enable the ADC module */ ADCCON3bits.DIGEN7 = 1;       // Enable ADC7

while (1) {
/* Trigger a conversion */ ADCCON3bits.GSWTRG = 1;

/* Wait the conversions to complete */
while (ADCDSTAT1bits.ARDY7 == 0);
/* fetch the result */
result[0] = ADCDATA7;

while (ADCDSTAT1bits.ARDY8 == 0);
/* fetch the result */
result[1] = ADCDATA8;

while (ADCDSTAT1bits.ARDY9 == 0);
/* fetch the result */
result[2] = ADCDATA9;

/*
* Process results here
*
* Note 1: Loop time determines the sampling time since all inputs are Class 2.
* If the loop time happens is small and the next trigger happens before the
* completion of set sample time, the conversion will happen only after the
* sample time has elapsed.
*
* Note 2: Results are in fractional format
*
*/
}
return (1);
}