我跟着this Tutorial并更改了我的微控制器16f1827的代码。我也改变了代码的功能。如果ADC值超过最大值的一半,它应该打开LED。 ADC值如果不到一半则关闭LED。
// CONFIG
#pragma config FOSC = HS // Oscillator Selection bits (HS oscillator)
#pragma config WDTE = OFF // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = OFF // Brown-out Reset Enable bit (BOR disabled)
#pragma config LVP = OFF // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3 is digital I/O, HV on MCLR must be used for programming)
#pragma config CPD = OFF // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)
#pragma config WRT = OFF // Flash Program Memory Write Enable bits (Write protection off; all program memory may be written to by EECON control)
#pragma config CP = OFF // Flash Program Memory Code Protection bit (Code protection off)
#include <xc.h>
#include <pic16f1827.h>
#define _XTAL_FREQ 8000000
void ADC_Init()
{
ADCON0 = 0x81; //Turn ON ADC and Clock Selection
ADCON1 = 0x00; //All pins as Analog Input and setting Reference Voltages
}
unsigned int ADC_Read(unsigned char channel)
{
if(channel > 7) //Channel range is 0 ~ 7
return 0;
ADCON0 &= 0xC5; //Clearing channel selection bits
ADCON0 |= channel<<3; //Setting channel selection bits
__delay_ms(2); //Acquisition time to charge hold capacitor
GO_nDONE = 1; //Initializes A/D conversion
while(GO_nDONE); //Waiting for conversion to complete
return ((ADRESH<<8)+ADRESL); //Return result
}
void main()
{
unsigned int a;
TRISA = 0xFF; //Analog pins as Input
TRISB = 0x00; //Port B as Output
//TRISC = 0x00; //Port C as Output
ADC_Init(); //Initialize ADC
do
{
a = ADC_Read(0); //Read Analog Channel 0
//PORTB = a; //Write Lower bits to PORTB
//PORTC = a>>8; //Write Higher 2 bits to PORTC
if(a > 512){
PORTBbits.RB7 = 1;
}else{
PORTBbits.RB7 = 0;
}
__delay_ms(100); //Delay
}while(1); //Infinite Loop
}
代码在XC8中编译时没有错误。问题是PIC检测到ADC变化太慢。如果我将输入引脚连接到正参考值,它会打开LED,延迟可能为2秒。当我将ADC输入更改为0v时也会发生同样的情况。检测到的所有更改都非常慢。为什么ADC工作这么慢?
答案 0 :(得分:2)
您链接的教程使用带有8MHz晶体振荡器的PIC16F877A,而您似乎尝试使用PIC16F1827及其内部振荡器而不是外部振荡器。仅像您一样更改PIC头文件是不够的。您还必须设置所需的振荡器模式,并处理两个部分之间不同的任何其他配置选项。我不确定,但我认为16F1827的默认内部振荡器频率是1MHz,而不是8MHz。这可能会解释您遇到的问题。
顺便说一句:不要试图捏造你的代码。确保正确配置微控制器,否则他们迟早会咬你的屁股。