#include <avr/io.h>
#include <util/delay.h>
#include <avr/signal.h>
#include <avr/interrupt.h>


#define fosc 12000000 //晶振12MHZ
#define baud 9600	 //波特率


unsigned char adcdata_temp[32];
unsigned char currenp;
unsigned char flag_start;


/********************* UART 初始化 ******************************/
void uart_Init(void)
{
	UCSR0A = 0x00;
	UCSR0B = (1<<RXEN0)|(1<<TXEN0)|(1<<RXCIE0);				//允許發(fā)送和接收
	/* 設(shè)置幀格式: 8 個(gè)數(shù)據(jù)位, 1 個(gè)停止位 */
	UCSR0C = (0<<USBS0)|(1<<UCSZ00)|(1<<UCSZ01);

	UBRR0L = (fosc/baud/16 - 1) % 256;
	UBRR0H = (fosc/baud/16 - 1) / 256;
}

/*************** 字符輸出函數(shù) ****************************/
void putchar(unsigned char c)
{	 
	while (!(UCSR0A&(1<<UDRE0)));
	UDR0=c;    
}

/**************** 字符輸入函數(shù) ***************************/	
unsigned char getchar(void)
{
	while(!(UCSR0A& (1<<RXC0)));
	return UDR0;
}

/*************** 字符串輸出函數(shù)	*************************/	
int puts(char *s)
{
	while (*s)
	{
		putchar(*s);
		s++;
	}	
	putchar(0x0a);//回車換行
	putchar(0x0d);

	return 1;
}

/*************** 串口接收中斷	*************************/
SIGNAL(SIG_USART_RECV)
{
	if(getchar()=='s') 
	{
		flag_start = 1;
		puts("ADC Start!");
	}

	if(getchar()=='q')
	{
		flag_start = 0;
		puts("ADC Stop...");
	}
}

/********************* 顯示整數(shù) ***********************/
void putnum(unsigned char  x) 
{ 
 	if(x>10)
		putnum(x/10); 		//判斷是否大于10，大于10則繼續(xù)調(diào)用函數(shù)本身，直到x<10，這里用了遞歸
 	putchar(x%10 + '0'); 	//否則小于10，或已執(zhí)行上一步部，對十求余得個(gè)位數(shù)，然后通過字符"0"內(nèi)碼加一得各個(gè)位數(shù)字的內(nèi)碼
} 

/********************* 讀取AD值 ******************************/
unsigned char ReadADC(void)
{
	unsigned int ADC_value;

	ADCSRA |= (1<<ADEN);                //使能ADC
	ADCSRA |= 0x06;                     //64分頻，6M/64=93.75K

	ADMUX = 0x41;                       //AVCC， AREF 引腳外加濾波電容，左對齊，通道1
	ADMUX |= (1<<ADLAR); 				//左對齊，將讀取ADCH（高8位),ADCL（最低2位）將拋棄

	ADCSRA |= (1<<ADSC);                //啟動(dòng)單次轉(zhuǎn)化
	_delay_us(50);
	while(!(ADCSRA & (1<<ADIF)));       //等待轉(zhuǎn)化結(jié)束
	ADCSRA |= (1<<ADIF);                //清除中斷標(biāo)志
	ADC_value = ADCH;					//只讀高字節(jié)，當(dāng)作8位AD使用
	ADCSRA = 0;                         //關(guān)閉ADC
	return(ADC_value);
}

/********************* 主函數(shù) ******************************/

int main(void)
{
  	unsigned char i;
  	unsigned int adc_average, adc_temp;

	DDRC = 0x01;
	PORTC = 0x01;

	DDRD = 0xFE;
	PORTD = 0xFE;

	sei();

	uart_Init();

	while(1)
	{
		if(flag_start==1)
		{
			adc_temp = ReadADC();

			adcdata_temp[currenp] = adc_temp;
			currenp++;

			if(currenp>=32)
			{
				currenp = 0;
				adc_average = 0;
				for(i=0;i<32;i++)
				{
					adc_average = adc_average + (unsigned int)adcdata_temp[i];
				}
				adc_average = adc_average>>5;
				putnum(adc_average);
				putchar(0x0a);			//回車換行
				putchar(0x0d);
			}
  		}

		_delay_ms(2);

		PORTC ^= 0x01;
	}

  	return 0;
}