[chukhivuitinh]

Em xin tách ra cho dễ nhìn nha ^_^ :
ADC:

#define SAMPLINGRATE    1800
#define SAMPCOUNT       (FCY/SAMPLINGRATE)+1	//dung cho TMR3 cho ADC

#define adc_read(pin) 	adc_buf[pin]

unsigned int adc_buf[16];
volatile unsigned int* ADC16Ptr = &ADCBUF0; 		//Pointer to ADC register buffer, 
unsigned int adc_filter_buffer[4][6] = { {0,0,0,0,0,0},{0,0,0,0,0,0},{0,0,0,0,0,0},{0,0,0,0,0,0} };
unsigned int current_buf = 1;

//==== ADC ====
void adc_init()
{
    adc_stop();					// reset adc 
	//====ADCON1====
	ADCON1bits.SIMSAM = 0;  		// SIMSAM = 0 lay mau tung kenh 1 cach tuan tu
							// SIMSAM = 1 lay mau 4 kenh (0,1,2,3) 1 cach dong thoi
        ADCON1bits.FORM = 0b00;  		// output la integer
    	ADCON1bits.SSRC = 0b010;     	// chon bo dem de chuyen doi (3bit) => dung Timer 3 de dem 
    	ADCON1bits.ASAM = 1;      		// 1 : tu dong tiep tuc lay mau khi chuyen doi xong ,bit SAMP tu dong set
							// 0 : chuyen doi xong ,doi bit SAMP set thi moi tiep tuc lay mau
	//====ADCON2====
	ADCON2bits.SMPI = 5;    		// SMPI gom 4bit ,tuong ung uC ngat khi 1->16 lan lay mau 
    	ADCON2bits.CHPS = 0;    		// CHPS = 00 chon kenh 0 de chuyen doi
    							// CHPS = 01 chon kenh 0 va kenh 1 de chuyen doi
							// CHPS = 1x chon tat ca cac kenh de chuyen doi
    	ADCON2bits.BUFM = 0;  		// BUFM = 0 lay 1 lan 16 bit 
							// BUFM = 1 lay 2 lan ,moi lan 8 bit 			
   	ADCON2bits.BUFS = 0;
	ADCON2bits.ALTS = 0;    		// ALTS = 0 luon luon su dung MUX A lam bo don kenh
							// ALTS = 1 ban dau dung Mux A ,sau do xen ke MuxB va Mux A lam bo don kenh
    	ADCON2bits.CSCNA = 1;   		// 1 quet ngo vao 
							// 0 ko quet
    	ADCON2bits.VCFG = 0b000; 		// 3bit : chon nguon tham khao => dung AVdd va AVss
	//====ADCON3====
	ADCON3bits.SAMC = 0b11111;	// dung 31 Tad cho lay mau
	ADCON3bits.ADRC = 0;			// dung clock he thong
	ADCON3bits.ADCS = 0b011111;    	// chon xung chuyen doi (6bit tuong ung 1->32xTcy)
	//====ADCHS====
    	ADCHSbits.CH0SA = 2;    		// CH0SA = 0 chon nguon duong cua kenh A la AN0
							// CH0SA = x chon nguon duong cua kenh A la ANx
	ADCHSbits.CH0NA = 0;   		// CH0NA = 0 chon nguon am cua kenh A la Vref-
							// CH0NA = 1 chon nguon am cua kenh A la AN1
    				// chon nguon am duong cho cac kenh 1,2,3
    	ADCHSbits.CH123SA = 0;  
    	ADCHSbits.CH123NA = 0;  
    
    				// MUX B Input Select
    	ADCHSbits.CH123SB = 0;  
    	ADCHSbits.CH123NB = 0;  
    //====ADCSSL====
	ADCSSL = 0b0000000000111100;   	// Scan AN2..AN5 quet chan nao thi cho chan do len 1
							// adc_buf tinh tu bit2=>5 ,vay adc_buf[0] = quet chan AN2
	//====ADPCFG====
    	ADPCFG = 0xFF00;         		// AN0..AN7 la analog
							// 0 : ngo vao la analog
							// 1 : ngo vao la digital
    //==== khai bao PORTB ====	
	TRISB = 0b11111111;      		// Port B la input
    
    // INITIALIZE TIMER3 (dung cho bo dem ADC)
    	TMR3 = 0x0000;
    	PR3 = SAMPCOUNT;
    	IFS0bits.ADIF = 0;       			// Clear the A/D interrupt flag bit
    	IEC0bits.ADIE = 1;       			// Set the A/D interrupt enable bit 
}

void adc_start()
{
    ADCON1bits.ADON = 1;

    T3CONbits.TON = 1;	
}

void adc_stop()
{
    ADCON1bits.ADON = 0;

    T3CONbits.TON = 0;
}

void __attribute__((__interrupt__)) _ADCInterrupt(void)
{
	unsigned int i;
	
	for (i=0; i < 6; i++)
  		adc_filter_buffer[current_buf][i] = ADC16Ptr[i];

    for (i=0; i < 6; i++)
     	adc_buf[i] = (adc_filter_buffer[current_buf][i]/6 + 
     	              adc_filter_buffer[(current_buf+1)%4][i]/6 +
     	              adc_filter_buffer[(current_buf+2)%4][i]/3 +
     	              adc_filter_buffer[(current_buf+3)%4][i]/3);
	current_buf = (current_buf+1) % 4;
	
	IFS0bits.ADIF = 0;
}

típ UART :

#define BAUDRATE 		9600   
#define U1BRG    		FCY/16/BAUDRATE -1		//dung cho UART

//==== UART1 ====

void uart1_close()
{
	CloseUART1();					// co san trong uart.h cua microchip	
}

void uart1_open()
{
	unsigned int baudvalue;   
	unsigned int U1MODEvalue;
	unsigned int U1STAvalue; 

	uart1_close();
	ConfigIntUART1(UART_RX_INT_DIS & UART_TX_INT_DIS);
	baudvalue = U1BRG;

    U1MODEvalue = 0x8000;
				
    U1STAvalue  = 0x0400;
				               
	OpenUART1(U1MODEvalue, U1STAvalue, baudvalue);
}

void uart1_puts(char string[])
{
	putsUART1 ((unsigned int *)string);  			// lay gia tri de gui di 
	while (BusyUART1());
}

hàm main :

//==== ham main ===
int main()
{
	float tb;
	
	adc_init();
	adc_start();

	uart1_open();
		
	while(1)
	{						
		float trungbinh_AN0()
			{
				return (((float)adc_read(AN0) / 65500.0*5.)-2.5)/0.002; // gia tri so voi trung binh /don vi
			}
			tb = trungbinh_AN0();
			
			PrintSignedInteger(tb, &uart1_puts); // Send result to uart
			uart1_puts("\n\r");
	}
	
	uart1_close();
	return 0;
}

void PrintSignedInteger(int x, void (*printer)(char[]))
{
	static char tmpChar[2] = "0";
	unsigned int radix, i, converted;
	char emptyChar = ' ';
	
	if (x < 0)
	{
		printer("-");
		x*=-1;
	}
	else if (x == 0)
	{
		printer("0");
		return;	
	}
	converted = (unsigned int) x;
	

	// auto-align on 16bit size (655.. = 5 positions)
	for (radix=10000, i=0; i < 5; radix/=10, i++)
	{
		if (converted > radix-1) 
		{
			tmpChar[0] =  '0' + (converted/radix);
			printer(tmpChar);
			converted = converted % radix;
			emptyChar = '0';
		} 
		else if (emptyChar == '0') 
		{
			printer("0");
		}
	}
}

Mấy bác giúp em với nha ,em vẫn chưa tìm được lỗi ở đâu ,ban đầu nghĩ ở chỗ ngắt AD ,rùi chỗ lấy adc_buf ,rùi hàm truyền lên pc ,nhưng đều ko fải ,hihixhix