B4R Question Sensor ds18b20 strange readings

Cesar_Morisco

Active Member
Hello everyone, everything good
I am using ds18b20 sensor on esp8266
When the Temperature exceeds 128 degrees it starts showing Negative Temperature - 123 degrees. Can anyone tell me. Thanks.
Using this example

 

hatzisn

Well-Known Member
Licensed User
Longtime User
Hello everyone, everything good
I am using ds18b20 sensor on esp8266
When the Temperature exceeds 128 degrees it starts showing Negative Temperature - 123 degrees. Can anyone tell me. Thanks.
Using this example


I have never used it but what you have mentioned forces me to think that it presents the temperature as signed byte. Try to assign to a ubyte variable the result of Bit.And(temperature, 0xff).
 
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Cesar_Morisco

Active Member
I have never used it but what you have mentioned forces me to think that it presents the temperature as signed byte. Try to assign to a ubyte variable the result of Bit.And(temperature, 0xff).
Hi Hatzis How are you?
I think the ds18b20 limit is -55 to 125, even from the research I did
I need a sensor that reads from 0 to 300 degrees
Thank you from the bottom of my heart for your answer

fotos
When the temperature goes above 128 it becomes negative
 

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rbghongade

Active Member
Licensed User
Longtime User
Hi
You can use MAX31865 with RTD or MAX31855 with thermocouple for measuring high temperatures. Libraries for both are available for Arduino and we can use them with inline C with B4R. I have used RTD successfully.
 
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hatzisn

Well-Known Member
Licensed User
Longtime User
Hi Hatzis How are you?
I think the ds18b20 limit is -55 to 125, even from the research I did
I need a sensor that reads from 0 to 300 degrees
Thank you from the bottom of my heart for your answer

fotos
When the temperature goes above 128 it becomes negative

I was not aware of this. Thanks. I suppose my assumption was completely wrong.
 
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Hi
You can use MAX31865 with RTD or MAX31855 with thermocouple for measuring high temperatures. Libraries for both are available for Arduino and we can use them with inline C with B4R. I have used RTD successfully.

Additionally MAX6675 is also Thermocouple Temperature Measurement IC.
Maybe it compete MAX31855 in some features or price. I use it and have good results. Good luck...
 
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Cesar_Morisco

Active Member
Hi
You can use MAX31865 with RTD or MAX31855 with thermocouple for measuring high temperatures. Libraries for both are available for Arduino and we can use them with inline C with B4R. I have used RTD successfully.
Hello rbghongade how are you?
Thanks for your response.
A hug
 
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