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"temp" command seems to read high

PostPosted: Thu Nov 26, 2015 12:48 pm
by heckler
I am running the thermostat example program on an esp8266-01 and it seems to me that the displayed temperature is around 10 degrees high.

I have tried a couple of different ds18b20 sensors and then read them from a separate PIC microcontroller sitting right next to the esp module and they are different by around 10 degrees

could there be a math "bug" in the 'temp' command??

thanks
dwight

Re: "temp" command seems to read high

PostPosted: Thu Nov 26, 2015 2:21 pm
by matherp
Works OK for me but it is sensitive to the electrical environment.

I use a 4K7 pullup on the data pin and a 0.1uF capacitor directly across the power pins. Without the capacitor I get some randomness in the readings

Re: "temp" command seems to read high

PostPosted: Thu Nov 26, 2015 10:37 pm
by Rotohammer
I think you're on to something, I have two units and one was about 10 degrees too high, but I thought it had to do with the short leads causing it to pull heat from the ESP12 clocked at 160Mhz. I will dig into this.

Re: "temp" command seems to read high

PostPosted: Thu Nov 26, 2015 10:46 pm
by heckler
Thanks Rotohammer,

I have tried a few sensors and they are all 10 deg C higher as compared to a PIC microcontroller reading the same tested sensors sitting on the table next to each other.

dwight