請問版主的意思是
直接把
PSPMODE=0;
這樣設定嗎?
我是直接這樣設定,但是RE2那支接腳還是不能使用耶
而ADCON1沒有設錯

檢查一下 TRISE 裡的 PAPMODE 位元是否被設為 1。

檢查 ADCON1 裡的 PCFG0~PCFG3 的設定。

哈~~萬分感謝版主的回答..
我之前以為那個DELAY是要加在切channel之間~~~
原來如此~~
還有一個問題可以請教一下嗎?

就是為啥我RE2這個輸入接腳在A/D時不能使用呢?

謝謝!

採樣 (充電) 時間不足造成。

正確的AD使用法為：切到新的通道後，要延遲一下，讓內部的SAMPLE&HOLD電容充份充/放電 (即和外部的類比電位一樣高)，才能將GO設為1 (即斷開SAMPLE&HOLD電容和外界的連線)，開始做ADC的轉換。

各位前輩:
小弟最近想用PIC16F877取多個通道的A/D轉換,我是參考此網站右邊"教材及講義區 ==> WORKSHOP ==> HI-TECH C 講義及實作裡面的lab3";但是此範例是PIC16F877A的範例,且此範例只取一個channel,因此小弟將程式修改如下:

希望各位前輩能夠撥空幫我看看為何,我取單一channel時不會有問題,但是取多channel時卻會有互相干擾的問題?
另外,為何我第8個channel(RE2)不能使用?

拜託各位前輩能給我這個初入門的人解答,萬分感謝!!

#include <pic.h>
#include "MID_LCD.h"


void A2D_0( unsigned char );
void A2D_1( unsigned char );
void A2D_2( unsigned char );
void LCD_ItoA(unsigned int);
unsigned char Set_BCD_ASCII(unsigned char);




unsigned int AD_Temp;
unsigned int AD_Temp_1;
unsigned int AD_Temp_2;
bit DS_Zero_Flag;

union {
int AD_10bit;
struct {
char AD_LSB;
char AD_MSB;
}AD_Byte;
}AD_Int;

union {
int AD_10bit_1;
struct {
char AD_LSB_1;
char AD_MSB_1;
}AD_Byte_1;
}AD_Int_1;

union {
int AD_10bit_2;
struct {
char AD_LSB_2;
char AD_MSB_2;
}AD_Byte_2;
}AD_Int_2;
/*****************************
DELAY FUNCTION
*****************************/

void delay_x_ms(int);
void del_1ms(void);

void delay_x_ms(int N_ms)
{
int Loop_ms;

for(Loop_ms = 0;Loop_ms<N_ms;Loop_ms++)
{
del_1ms();
}
}

void del_1ms(void)
{
int del_1ms;
for(del_1ms = 0;del_1ms<199;del_1ms++)
{
asm("nop");
asm("nop");
}
}

/***********************************
Convert A/D Channel
************************************/

void A2D_0( unsigned char channel )
{
unsigned char temp; // Temp storage
ADCON0=0b10000001;

temp = channel << 3; // Shift channel value three bits left
ADCON0 &= 0b11000111; // Clear channel select bits in ADCON0
ADCON0 |= temp; // Logically OR shifted channel value into place in ADCON0

ADGO = 1; // Initiate conversion on selected channel
while (ADGO) ; // Poll ADGO bit until it clears, indicating conv. done
AD_Int.AD_Byte.AD_MSB=ADRESH;
AD_Int.AD_Byte.AD_LSB=ADRESL;
}

void A2D_1( unsigned char channel_1)
{
unsigned char temp; // Temp storage
ADCON0=0b10001001;

temp = channel_1 << 3; // Shift channel value three bits left
ADCON0 &= 0b11000111; // Clear channel select bits in ADCON0
ADCON0 |= temp; // Logically OR shifted channel value into place in ADCON0

ADGO = 1; // Initiate conversion on selected channel
while (ADGO) ; // Poll ADGO bit until it clears, indicating conv. done
AD_Int_1.AD_Byte_1.AD_MSB_1=ADRESH;
AD_Int_1.AD_Byte_1.AD_LSB_1=ADRESL;
}

void A2D_2( unsigned char channel_2)
{
unsigned char temp; // Temp storage
ADCON0=0b10010001;

temp = channel_2 << 3; // Shift channel value three bits left
ADCON0 &= 0b11000111; // Clear channel select bits in ADCON0
ADCON0 |= temp; // Logically OR shifted channel value into place in ADCON0

ADGO = 1; // Initiate conversion on selected channel
while (ADGO) ; // Poll ADGO bit until it clears, indicating conv. done
AD_Int_2.AD_Byte_2.AD_MSB_2=ADRESH;
AD_Int_2.AD_Byte_2.AD_LSB_2=ADRESL;
}

//***************************************
//* Program Main ( ) *
//***************************************
void main(void)
{
OpenLCD();
ADCON1=0b10000000; //all channel is A/D input and Right justified
TRISA0=1;
TRISA1=1;
TRISA2=1;
TRISA3=1;
TRISA4=1;
TRISA5=1;
TRISE0=1;
TRISE1=1;
TRISE2=1;
TRISC=0x00; // Set PortC for Output
PORTC=0x80; // Initila LED display = 0x80

while(1)
{
A2D_0(0x00); // Get 10-bit A/D result from CH0
LCD_Set_Cursor(0,0);
LCD_ItoA(AD_Int.AD_10bit);
delay_x_ms(100);
A2D_1(0x01); // Get 10-bit A/D result from CH1
LCD_Set_Cursor(6,0);
LCD_ItoA(AD_Int_1.AD_10bit_1);
delay_x_ms(100);
A2D_2(0x02); // Get 10-bit A/D result from CH2
LCD_Set_Cursor(0,1);
LCD_ItoA(AD_Int_2.AD_10bit_2);
delay_x_ms(100);

}

}

void LCD_ItoA(unsigned int AD_Data)
{
AD_Temp=AD_Data;
DS_Zero_Flag=1;

putcLCD(Set_BCD_ASCII(AD_Data/1000)); // 顯示千位數
AD_Temp=AD_Temp%1000; // 取出百位以後的數

putcLCD(Set_BCD_ASCII(AD_Temp/100)); // 顯示百位數
AD_Temp=AD_Temp%100;

putcLCD(Set_BCD_ASCII(AD_Temp/10)); // 顯示十位數
AD_Temp=AD_Temp%10;

putcLCD(AD_Temp+='0'); // 顯示個位數
}


unsigned char Set_BCD_ASCII(unsigned char BCD_Data)
{
if (BCD_Data==0)
{
if (DS_Zero_Flag) return ' '; // 居先零抑制
else return '0'; // 顯示一般的零
}
else
{
DS_Zero_Flag=0; // 取消居先零的抑制
return (BCD_Data +='0'); // 並傳回 ASCII Code
}
}