dspic30f4011 problema adc

//inizializzazione adc ADCON1bits.ADON=0; ADCON1bits.ADSIDL=0; // 0 = Continue module operation in Idle mode ADCON1bits.FORM=0b00; // 00 = Integer (DOUT = 0000 00dd dddd dddd) ADCON1bits.SSRC=0b111; // 111 = Internal counter ends sampling and starts conversion (auto convert) ADCON1bits.SIMSAM=1; // 1 = Samples CH0, CH1, CH2, CH3 simultaneously (when CHPS = 1x) ADCON1bits.ASAM=1; // 0 = Sampling begins when SAMP bit set ADCON1bits.SAMP=0; // When ASAM = 0, writing ‘1’ to this bit will start sampling ADCON2bits.VCFG=0b000; // AVSS AVDD selected ADCON2bits.CSCNA=0; // do not scan imputs ADCON2bits.CHPS=0b10; // 1x = Converts CH0, CH1, CH2 and CH3 ADCON2bits.SMPI=0b1111; // 1111 = Interrupts at the completion of conversion for each 16th sample/convert sequence ADCON2bits.BUFM=0; // 0 = Buffer configured as one 16-word buffer ADCBUF(15...0) ADCON2bits.ALTS=0; // 0 = Always use MUX A input multiplexer settings ADCON3bits.SAMC=0b01000; // 01000 = 8 TAD max = 11111 0 32 TAD ADCON3bits.ADRC=0; // 0 = Clock derived from system clock ADCON3bits.ADCS=0b001011;// = TCY/2 • (ADCS<5:0> + 11) ADCHSbits.CH123NB=0b00; // come sotto ADCHSbits.CH123SB=0; // ADCHSbits.CH0NB=0; // ADCHSbits.CH0SB=0b0011; // ADCHSbits.CH123NA=0b00; // CH1, CH2, CH3 negative input is VREF- ADCHSbits.CH123SA=0; // CH1 positive input is AN0, CH2 positive input is AN1, CH3 positive input is AN2 ADCHSbits.CH0NA=0; // Channel 0 negative input is VREF- ADCHSbits.CH0SA=0b0011; // Channel 0 Positive Input Select for MUX A Multiplexer Setting bits Channel 0 positive input is AN3 ADPCFGbits.PCFG0=0; // 0 = Analog input pin in Analog mode AN0/RB0 ADPCFGbits.PCFG1=0; // 0 = Analog input pin in Analog mode AN1/RB1 ADPCFGbits.PCFG2=0; // 0 = Analog input pin in Analog mode AN2/RB2 ADPCFGbits.PCFG3=0; // 0 = Analog input pin in Analog mode AN3/RB3 ADPCFGbits.PCFG4=1; // 0 = Analog input pin in DIGITAL mode AN4/RB4 ADPCFGbits.PCFG5=1; // 0 = Analog input pin in DIGITAL mode AN5/RB5