How to convert MAX31865

sky999

How to convert MAX31865 [Copy link]

The default resistor for MAX31865 is 400R. The conversion is as shown in the table below. However, there is no 400R resistor, so a 430 resistor is used. How can I adjust it?

My room temperature is around 30 degrees, and the measured value is 421Ah

MAX31865.pdf (713.65 KB, downloads: 7)

2020-9-12 19:34 上传

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littleshrimp

Use ADC CODE to calculate the resistance of the RTD according to this formula, and then calculate the temperature

chunyang

The output remains unchanged, indicating that there must be something wrong with the original poster's programming or circuit. The reference resistor can have a wide range of values, from 350 ohms to 10k, and there is a conversion formula.

sky999

littleshrimp posted on 2020-9-12 20:52 Use ADC CODE to calculate the resistance of the RTD according to this formula, and then calculate the temperature

I calculated RTD≈111, and looked up the table to get about 30 degrees, which is correct. My room temperature should be around 30 degrees, but how can I use the formula to calculate the actual temperature? It seems that there is no such formula.

littleshrimp

sky999 posted on 2020-9-12 22:26 Calculate RTD≈111, and look up the table to get about 30 degrees, which is correct. My room temperature should be around 30 degrees, but how can I use the formula to calculate the actual temperature? ...

See if this post helps you https://m.eeworld.com.cn/bbs_thread-553748-1-1.html

sky999

littleshrimp posted on 2020-9-12 22:53 See if this post helps you https://m.eeworld.com.cn/bbs_thread-553748-1-1.html

His table lookup is useless and wastes memory. I have already figured out the formula. Thank you very much.

littleshrimp

sky999 posted on 2020-9-12 22:56 His table lookup is useless and wastes memory. I have already thought of the formula. Thank you very much

The change of RTD resistance with temperature is not linear, so a scale is needed.