main.c

NTC热敏电阻测温

//***************************************************
//*功能：NTC测温									*
//*硬件：AtemlMega16L 	LCM1286*64 ST7920 			*
//*		 NTC MF58502F327 R=5K B=3270K				*
//*编译：WinAVR-20050214							*	
//*作者：陈崇 QQ:86395850 EMAIL:[e-mail]   *
//*日期：2007.5.29									*
//***************************************************

#include <avr/io.h>
#include <avr/delay.h> 
#include <avr/interrupt.h>
#include <avr/signal.h>
#include <avr/pgmspace.h>
#include <lcm12864.h>

#define	 VREF 4740										//	实测的Vref引脚电压@4.74V供电
#define  R	  5020										//	分压电阻
#define  VCC  4740	 									//	电源电压mV
const unsigned char  icon_rt[] PROGMEM=				//	热敏电阻
	{
		0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x1C,0x00,0x02,0x00,0x1F,0xF8,0xF1,0x0F,
		0x10,0x88,0x1F,0xF8,0x00,0x40,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
	};
const unsigned char  icon_volt[] PROGMEM=				//	电压表
	{
		0x00,0x00,0x00,0x00,0x00,0x00,0x1F,0xFC,0x10,0x04,0x12,0x24,0x12,0x24,0x11,0x44,
		0x10,0x84,0x1F,0xFC,0x10,0x04,0x12,0x24,0x10,0x04,0x1F,0xFC,0x00,0x00,0x00,0x00,
	};
const unsigned char  icon_temp[] PROGMEM=				//	温度计
	{
		0x00,0x00,0x03,0xD0,0x02,0x46,0x03,0x48,0x02,0x48,0x03,0x46,0x02,0x40,0x03,0x40,
		0x02,0x40,0x03,0x40,0x02,0x40,0x02,0x40,0x04,0x20,0x04,0x20,0x02,0x40,0x01,0x80,
	};
const unsigned int  vt_table[] PROGMEM=				// 电压温度对照表
	{
		4132,4098,4063,4026,3988,3949,3908,3866,3823,3779,
		3733,3686,3639,3590,3540,3489,3437,3385,3331,3277,
		3222,3166,3110,3054,2997,2940,2882,2824,2767,2709,
		2651,2593,2536,2478,2421,2365,2309,2253,2198,2143,
		2089,2036,1984,1932,1881,1831,1782,1734,1686,1640,
		1594,1550,1506,1464,1422,1381,1341,1303,1265,1228,
		1192
	
	};
	
unsigned int temp;				//	温度
unsigned int adc_volt;			//	测试点电压
unsigned int rt;				//	热敏电阻
//***********************************************************************
//*名称: unsigned int GetADC(unsigned char adc_channel)					*	 
//*功能: 获取ADC转换值程序												*
//*参数: adc_channel 转换通道                  							*
//*返回: ADC值                             								*
//***********************************************************************
unsigned int GetADC(unsigned char adc_channel)
   {
		unsigned char i;
		unsigned int adc_value[8];					// AD转换缓冲区	
		unsigned int adc_value_ave=0;
		unsigned int max_value=0,min_value=0,max_index=1,min_index=1;
		ADMUX=((1<<REFS0)|adc_channel); 				// 选择ACC参考电压和测试转换通道
		for(i=0;i<8;i++)								// 连续AD转换8次	
			{
				ADCSRA|=(1<<ADSC);						// 启动AD转换
				loop_until_bit_is_set(ADCSRA,ADIF); 	// 等待AD转换结束
				ADCSRA|=(1<<ADIF); 					// 写1清除标志位
				adc_value[i]=ADC;   					// 将单次ADC转换结果=ADCH:ADCL放入缓冲区									
				
			}
		for(i=1;i<8;i++)								// 去掉第一次测量值
			{
				adc_value_ave+=adc_value[i];	
			}
		adc_value_ave/=7;								// 去掉一个值外的平均值							
		for(i=1;i<8;i++)								// 计算最大值和最小值索引号
			{
				if(adc_value[i]>adc_value_ave)
					{
						if((adc_value[i]-adc_value_ave)>max_value)
							{
								max_value=adc_value[i];
								max_index=1;
							}
					}		
				else
					{
						if((adc_value_ave-adc_value[i])>min_value)
							{
								min_value=adc_value_ave-adc_value[i];
								min_index=i;
							}
					}
			}
		adc_value_ave=0;	
		for(i=1;i<8;i++)						// 计算去掉最大值和最小值后的总和
			{
				if((i!=max_index)&&(i!=min_index))
					{
						adc_value_ave+=adc_value[i];	
					}
			}
		if(max_index!=min_index)				// 如果测量值不同
			{
				adc_value_ave/=5;				// 计算平均值
			}
		else									// 如果测量值相同
			{
				adc_value_ave/=6;				// 计算平均值
			}
		ADCSRA&=~(1<<ADSC);					// 停止AD转换
		return adc_value_ave;
   }
//***********************************************************************
//*名称: unsigned char GetTemp(unsigned int adc_volt)  					*	 
//*功能: 获取温度值	程序												*
//*参数: adc_channel ADC电压                  							*
//*返回: 温度值                            								*
//***********************************************************************   
unsigned char GetTemp(unsigned int adc_volt)
	{
		unsigned char i;
		unsigned char temp=0;
		for(i=0;i<61;i++)
			{
				if(adc_volt>=pgm_read_word(vt_table+i))	//	查表计算温度
					{
						temp=i;
						if(temp<10)				//	-10~-1
							{
								temp|=0x80;		//	加负温度标志
							}
						else					//	0~50
							{
								temp-=10;
							}
						return temp;	
					}
			}
		temp=255;			//	如果超出范围返回255			
		return temp;
	}
int main(void)
	{
		PORTA=(1<<PA7)|(1<<PA6)|(1<<PA5);					//	PA7-PA5输出高电平
		DDRA|=(1<<PA7)|(1<<PA6)|(1<<PA5);					//	PA7-PA5设置为输出
		PORTD|=(1<<PD7)|(1<<PD0);							//	PD7 PD1 PD0输出高电平
		DDRD=(1<<PD7)|(1<<PD6)|(1<<PD1)|(1<<PD0);			//	PD7 PD6 PD1 PD0设置为输出
		ADCSRA|=(1<<ADEN);									// 使能ADC
		lcm12864_init();
		lcm12864_clear();
		lcm12864_cls_gdram();
		lcm12864_dis_string(2,0,"NTC 测温",0);
		lcm12864_dis_string(6,1,"Ω",0);
		lcm12864_dis_string(6,2,"mV",0);
		lcm12864_dis_string(6,3,"℃",0);
		lcm12864_dis_dot(2,1,icon_rt);
		lcm12864_dis_dot(2,2,icon_volt);
		lcm12864_dis_dot(2,3,icon_temp);
		while(1)
			{	

					adc_volt=(int)((long)GetADC(0)*VREF/1024);
					rt=(int)(((long)adc_volt*R)/(VCC-adc_volt));	
					temp=GetTemp(adc_volt);
					lcm12864_char_locate(4,1);
					lcm12864_dis_ascii(0x30+rt/1000);
					lcm12864_dis_ascii(0x30+rt%1000/100);
					lcm12864_dis_ascii(0x30+rt%100/10);
					lcm12864_dis_ascii(0x30+rt%10);						
					lcm12864_char_locate(4,2);
					lcm12864_dis_ascii(0x30+adc_volt/1000);
					lcm12864_dis_ascii(0x30+adc_volt%1000/100);
					lcm12864_dis_ascii(0x30+adc_volt%100/10);
					lcm12864_dis_ascii(0x30+adc_volt%10);					
					lcm12864_char_locate(4,3);
					if(temp&0x80)
						{
							lcm12864_dis_ascii('-');	
						}
					else
						{
							lcm12864_dis_ascii('+');
						}

					lcm12864_dis_ascii(0x30+temp%100/10);
					lcm12864_dis_ascii(0x30+temp%10);
			}	

	}