16 bit SD_ADC P24FJ128GC006

SD1CON1				= 0;
	SD1CON2				= 0;
	SD1CON3				= 0;	// Reset Adc.

	SD1CON1bits.SDRST	= 0;	// Release from Reset
	SD1CON1bits.SDGAIN	= 5;	// Gain is 32:1 for offset measurement and application
	SD1CON1bits.DITHER	= 1;	// Low Dither, because using SVDD as reference
	SD1CON1bits.VOSCAL	= 1;	// Internal Offset Measurement Enable
	SD1CON1bits.SDREFP 	= 0;	// Positive Voltage Reference is SVDD
	SD1CON1bits.SDREFN 	= 0;	// Negative Voltage Reference is SVSS
	SD1CON1bits.PWRLVL	= 1;	// High power mode

	SD1CON2bits.CHOP	= 3;	// Chopping should be enabled always
	SD1CON2bits.SDINT	= 3;	// Interrupt on every data output
	SD1CON2bits.SDWM	= 1;	// SDxRESH/SDxRESL updated on every Interrupt
	SD1CON2bits.RNDRES	= 2;	// Round result to 16-bit

	SD1CON3bits.SDDIV	= 1;	// Input Clock Divider is 2 (SD ADC clock is 4MHz)
	SD1CON3bits.SDOSR	= 0;	// Oversampling Ratio (OSR) is 1024 (best quality)
	SD1CON3bits.SDCS	= 1;	// Clock Source is 8MHz FRC
	SD1CON3bits.SDCH	= 1;	// Channel 1 is used for this demo code

	SD1CON1bits.SDON 	= 1;	// Enable the ADC module now that it is configured

       	for (i = 0; i<6; i++) // (value must be >= 5)
	{
		IFS6bits.SDA1IF = 0; 	//Clear interrupt flag
		while(IFS6bits.SDA1IF == 0); //Wait until hardware says we have a result ready.
		IFS6bits.SDA1IF = 0; 	//Clear interrupt flag
	}

	while(IFS6bits.SDA1IF == 0);//Wait until hardware says we have a result ready.
	IFS6bits.SDA1IF 	= 0;	//Clear interrupt flag
	offset 				= (signed short int)SD1RESH; // cast to accommodate the sign bit extend

      	// Switch off offset measurement mode, now that we have the value
	SD1CON1bits.SDON 	= 0;
	SD1CON1bits.VOSCAL 	= 0;
       SD1CON3bits.SDCH      = 1; // point to the input voltage
	SD1CON1bits.SDON      = 1; // SD_ADC back on to make next measurement
	// Wait for a minimum of five interrupts to be generated.
	for(count=0; count<6; count++)
	{
		// Clear interrupt flag.
		IFS6bits.SDA1IF = 0;
		// Wait for the result ready.
		while(IFS6bits.SDA1IF == 0);
	}
	// Save the maximum value to calculate the gain.
	maxValue = (signed short int) SD1RESH; // must cast as signed as is declared unsigned in header
	// Calculate gain.
	SD_gain = EXPECTED_MAX_VALUE/((double)((signed long int)maxValue-offset));

void INIT_ADC(void)
{
	SD1CON1				= 0;
	SD1CON2				= 0;
	SD1CON3				= 0;	// Reset Adc.

	SD1CON1bits.SDRST	= 0;	// Release from Reset
	SD1CON1bits.SDGAIN	= 5;	// Gain is 32:1 for offset measurement and application
	SD1CON1bits.DITHER	= 1;	// Low Dither, Vref+ = SVDD
	SD1CON1bits.VOSCAL	= 0;	// No Offset Measurement
//	SD1CON1bits.FILTDIS	= 0;
	SD1CON1bits.SDREFP 	= 0;	// Vref+ = SVDD
	SD1CON1bits.SDREFN 	= 0;	// Vref- = SVSS
	SD1CON1bits.PWRLVL	= 1;	// low power mode

	SD1CON2bits.CHOPSEL	= 3;	// Chopping should be enabled always
	SD1CON2bits.SDINT	= 2;	// Interrupt on every 5 data output
	SD1CON2bits.SDWM	= 0;	// SDxRESH/SDxRESL updated on every Interrupt
	SD1CON2bits.RNDRES	= 2;	// Round result to 16-bit

	SD1CON3bits.SDDIV	= 0;	// Input Clock Divider is 1 (SD ADC clock is 8MHz)
	SD1CON3bits.SDOSR	= 0;	// Oversampling Ratio (OSR) is 1024
	SD1CON3bits.SDCS	= 1;	// Clock Source is 8MHz FRC
	SD1CON3bits.SDCH	= 2;	// Channel 0 is used for this

	IFS6bits.SDA1IF		= 0;
	IEC6bits.SDA1IE		= 1;
	IPC26bits.SDA1IP	= 7;	// Highest Priority .

	SD1CON1bits.SDON 	= 1;	// Enable the ADC module now that it is configured
}

void __attribute__((__interrupt__,auto_psv)) _SDA1Interrupt(void)
{
//	if(SD1CON2bits.SDRESRDY)
	{
		SD1CON2bits.SDRESRDY = 0;
		printf("adc H %x, adc L %x\n", SD1RESH, SD1RESL);
	}
	IFS6bits.SDA1IF = 0; //Clear interrupt flag
}

result32 = (long)SD1RESH<< 16 | SD1RESL; 
or
result24 = (long)SD1RESH<< 8 | SD1RESL >> 8;