ads1220初始化

我目前在用ADS1220,目前有个问题不明白？我测量热电偶，用PT100做冷端补偿。热电偶T+接AIN2，T-接AIN3,PT100一端接AIN0，另一端接AIN1.

目前ADS1220初始化，

第一种情况：第一步测量热电偶的电压，AINP配置T+,AINN配置T-，正常模式，单次测量，使用PGA,增益32，数据更新20sps,试用内部基准，内部温度传感器关闭。像其他的AIN0，AIN1，恒流源灯还需要配置吗？第二步测量PT100，除了配置和PT100相关的，不相关的是否还需要配置？

第二种情况：还是一次性配置完ADS1220热电偶和PT100通道所有参数，然后切换通道读取每个通道测量数据？

我看了咱们的DEMO例程，每次读取数据前都是重新初始化，我不是很明白这是什么意思？咱们这样做有什么好处吗？希望给解释一下谢谢

还有一个问题：就是关于DRDY的。我使用查询的方法判断，比如如果一直是高电平。我不应该一直在这里死等，我应该有个超时判断。咱们这里的这个超时时间是怎么设定的？你看是不是这样的，1*数据更新速率相对应的时钟数目/256KHZ，是这样的吗？

user151383853：

这样 DEMO 程序稳定性不错, 但效率并不高.

其实推荐的是用中断去捕捉 DRDY 信号,   而超时判断是个好思路.  时间设置应该不小于 正常 DRDY 周期

tao wang16：

回复 user151383853:

1.超时时间是怎么设定的？你看是不是这样的，1*数据更新速率相对应的时钟数目/256KHZ，是这样的吗？比如我设置正常模式，数据采集是20sps,DRDY转换完时

钟是204850超时时间是不是1*204850/256。

2.ADS1220初始化两种情况：

A.采集热电偶，冷端是PT100,ADS1220初始化是我一次性配置完所有参数，然后切换通道读取通道数据.

B.第一步测量热电偶的电压，配置和热电偶相关的，不配置关于PT100的,然后采集读取数据。第二步配置和PT100相关的，不配置和热电偶相关的，然后采集读取数据。通过两次的采集计算温度。

这两种采用哪种配置呀？看DEMO都糊涂了。TI 的DEMO和我前面说的都不一样，TI的DEMO为什么这样，有什么好处吗？

void main (void){ Setup_SPI_Master (); ADS1220_Reset(); Setup_ADS1220 (ADS1220_MUX_AIN3_AIN2, ADS1220_OP_MODE_NORMAL, ADS1220_CONVERSION_SINGLE_SHOT, ADS1220_DATA_RATE_20SPS, ADS1220_GAIN_32, ADS1220_USE_PGA, ADS1220_IDAC1_AIN3, ADS1220_IDAC2_DISABLED, ADS1220_IDAC_CURRENT_250_UA, ADS1220_VREF_EXT_REF0_PINS);

__delay_cycles(CPU_CLK/2);

while (1) { // Configure ADS1220 for first RTD measurement Setup_ADS1220 (ADS1220_MUX_AIN3_AIN2, ADS1220_OP_MODE_NORMAL, ADS1220_CONVERSION_SINGLE_SHOT, ADS1220_DATA_RATE_20SPS, ADS1220_GAIN_32, ADS1220_USE_PGA, ADS1220_IDAC1_AIN3, ADS1220_IDAC2_DISABLED, ADS1220_IDAC_CURRENT_250_UA, ADS1220_VREF_EXT_REF0_PINS); __delay_cycles(CPU_CLK/1000); ReadConversionData = 0; ADS1220_Start (); while (!ReadConversionData); // Wait for Data Ready interrupt ADS1220_Get_RTD_Conversion_Data_Calibrated (&ADS1220RTDdata); // Get the temperature data with the calibration value subtracted // Configure ADS1220 for second chopped RTD measurement Setup_ADS1220 (ADS1220_MUX_AIN2_AIN3, ADS1220_OP_MODE_NORMAL, ADS1220_CONVERSION_SINGLE_SHOT, ADS1220_DATA_RATE_20SPS, ADS1220_GAIN_32, ADS1220_USE_PGA, ADS1220_IDAC1_AIN3, ADS1220_IDAC2_DISABLED, ADS1220_IDAC_CURRENT_250_UA, ADS1220_VREF_EXT_REF0_PINS); RTDtemperature = ADS1220RTDdata; __delay_cycles(CPU_CLK/1000); // ReadConversionData = 0; ADS1220_Start (); // Only one start needed for Continuous Mode while (!ReadConversionData); // Wait for Data Ready interrupt ADS1220_Get_RTD_Conversion_Data_Calibrated (&ADS1220RTDdata); // Get the temperature data with the calibration value subtracted

// Configure ADS1220 for first Thermocouple measurements Setup_ADS1220 (ADS1220_MUX_AIN0_AIN1, ADS1220_OP_MODE_NORMAL, ADS1220_CONVERSION_SINGLE_SHOT, ADS1220_DATA_RATE_20SPS, ADS1220_GAIN_32, ADS1220_USE_PGA, ADS1220_IDAC1_AIN3, ADS1220_IDAC2_DISABLED, ADS1220_IDAC_CURRENT_250_UA, ADS1220_VREF_INTERNAL); RTDtemperature += ADS1220RTDdata; //now averaging RTD results RTDtemperature = RTDtemperature/2; RTDtemperature = interpolateRTDTemperatureValue (RTDtemperature); // Get the RTD temperature and convert into millidegrees C //cold junction compensation CJCcode = calc_CJC(RTDtemperature); // convert RTD temperature into thermocouple voltage

__delay_cycles(CPU_CLK/1000); //

ReadConversionData = 0; ADS1220_Start (); while (!ReadConversionData); // Wait for Data Ready interrupt ADS1220_Get_TC_Conversion_Data_Calibrated (&ADS1220TCdata); // Get the temperature data with the calibration value subtracted TCtemperature = ADS1220TCdata/2;

// Configure ADS1220 for second chopped Thermocouple measurements Setup_ADS1220 (ADS1220_MUX_AIN1_AIN0, ADS1220_OP_MODE_NORMAL, ADS1220_CONVERSION_SINGLE_SHOT, ADS1220_DATA_RATE_20SPS, ADS1220_GAIN_32, ADS1220_USE_PGA, ADS1220_IDAC1_AIN3, ADS1220_IDAC2_DISABLED, ADS1220_IDAC_CURRENT_250_UA, ADS1220_VREF_INTERNAL);

__delay_cycles(CPU_CLK/1000);

ReadConversionData = 0; ADS1220_Start (); // Only one start needed for Continuous Mode while (!ReadConversionData); // Wait for Data Ready interrupt ADS1220_Get_TC_Conversion_Data_Calibrated (&ADS1220TCdata); // Get the temperature data with the calibration value subtracted ADS1220TCdata = ADS1220TCdata/2; TCtemperature -= ADS1220TCdata; TCtemperature += CJCcode; //CJC TCtemperature = interpolateTCTemperatureValue (TCtemperature); // Get the temperature and convert into millidegrees C}

这是TI的DEMO 也是做热电偶采集，冷端补偿是PT100.这里面的初始化参数，有一样的也有不一样的，我看了它的初始化糊涂了。希望大家给解释一下

tao wang16：

回复 tao wang16:

TI的技术支持做什么呢？我问了好久了都没有答复？是不愿意解答还是怎么回事？还有我之前的一个帖子，TI的技术支持都没有给解决，比较失望？