【PT100】电阻探头温度传感器

float temp_value;										//温度变量

float code RTD_TAB_PT100[211] =   		// 表格是以5度为一步，即-200, -195, - 190.....
{
18.52,20.68,22.83,24.97,27.10,29.22,31.34,33.44,35.54,37.64,                  // -200 ~ -155   10
39.72,41.80,43.88,45.94,48.00,50.06,52.11,54.15,56.19,58.23,                  // -150 ~ -105
60.26,62.28,64.30,66.31,68.33,70.33,72.33,74.33,76.33,78.32,                  // -100 ~ -55
80.31,82.29,84.27,86.25,88.22,90.19,92.16,94.12,96.09,98.04,                  //        -50 ~ -5
100.00,101.95,103.90,105.85,107.79,109.73,111.67,113.61,115.54,117.47,        // 0   ~ 45
119.40,121.32,123.24,125.16,127.08,128.99,130.90,132.80,134.71,136.61,        // 50  ~ 95
138.51,140.40,142.29,144.18,146.07,147.95,149.83,151.71,153.58,155.46,        // 100 ~ 145
157.33,159.19,161.05,162.91,164.77,166.63,168.48,170.33,172.17,174.02,        // 150 ~ 195
175.86,177.69,179.53,181.36,183.19,185.01,186.84,188.66,190.47,192.29,        // 200 ~ 245
194.10,195.91,197.71,199.51,201.31,203.11,204.90,206.70,208.48,210.27,        // 250 ~ 295
212.05,213.83,215.61,217.38,219.15,220.92,222.68,224.45,226.21,227.96,        // 300 ~ 345
229.72,231.47,233.21,234.96,236.70,238.44,240.18,241.91,243.64,245.37,        // 350 ~ 395
247.09,248.81,250.53,252.25,253.96,255.67,257.38,259.08,260.78,262.48,        // 400 ~ 445
264.18,265.87,267.56,269.25,270.93,272.61,274.29,275.97,277.64,279.31,        // 450 ~ 495
280.98,282.64,284.30,285.96,287.62,289.27,290.92,292.56,294.21,295.85,        // 500 ~ 545
297.49,299.12,300.75,302.38,304.01,305.63,307.25,308.87,310.49,312.10,        // 550 ~ 595
313.71,315.31,316.92,318.52,320.12,321.71,323.30,324.89,326.48,328.06,        // 600 ~ 645
329.64,331.22,332.79,334.36,335.93,337.50,339.06,340.62,342.18,343.73,        // 650 ~ 695
345.28,346.83,348.38,349.92,351.46,353.00,354.53,356.06,357.59,359.12,        // 700 ~ 745
360.64,362.16,363.67,365.19,366.70,368.21,369.71,371.21,372.71,374.21,        // 750 ~ 795
375.70,377.19,378.68,380.17,381.65,383.13,384.60,386.08,387.55,389.02,        // 800 ~ 845
390.48        // 850
};

函数声明
float CalculateTemperature(float fR);

获取温度
		temp_value = (Adc0832_Get_Value(0)/256.0)*5.0;		//计算通道0的输出电压
		temp_value = ((temp_value/100)+0.195047)/((4.096-((temp_value/100)+0.195047))/2000);//计算PT100阻值
		temp_value = CalculateTemperature(temp_value);		//通过阻值计算温度

声明的函数

/***********************************************************************
*FunName:        float CalculateTemperature(float fR)
*
*In:                fR -> PT100的电阻值。
*                        
*Out:                fTem -> 测得的温度值。               
*
*Discription: 将电阻值查表算出温度值。
*
*Notes:         采用2分查找法。          ************************************************************************/
float CalculateTemperature(float fR)
{
	float fTem;
	float fLowRValue;
	float fHighRValue;        
	int   iTem;
	uchar i;
	uchar cBottom, cTop;

//			 if (fR < RTD_TAB_PT100[0])                // 电阻值小于表格最值低于量程下限。
//			 {
//							 return BELOW_LOW_LIMITE;
//		 }
//			if (fR > RTD_TAB_PT100[210])        // 电阻值大于表格最大值，超出量程上限 。
//			{
//							 return EXCESS_UP_LIMITE;
//			}

	cBottom = 0; 
	cTop    = 210;

	for (i=105; (cTop-cBottom)!=1; )        // 2分法查表。
	{
		if (fR < RTD_TAB_PT100[i])
		{
			cTop = i;
			i = (cTop + cBottom) / 2;
		}
		else if (fR > RTD_TAB_PT100[i])
		{
			cBottom = i;
			i = (cTop + cBottom) / 2;
		}
		else
		{
			iTem = (uint)i * 5 - 200;
			fTem = (float)iTem;
			return fTem;
		}
	}

	iTem = (uint)i * 5 - 200;
	fLowRValue  = RTD_TAB_PT100[cBottom];
	fHighRValue = RTD_TAB_PT100[cTop];
	fTem = ( ((fR - fLowRValue)*5) / (fHighRValue - fLowRValue) ) + iTem;        // 表格是以5度为一步的。
	return fTem;
}

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