Post by model on Jan 29, 2023 4:01:13 GMT -8
I am reading PH14.45 with my ph sensor in water and obviously should be around 7, so have been digging around the calculation after showing my sensor as being read correctly by another ESP32. is there a blog post on PH offset as I could only find the test page with all the useful python test routines?
The calculation in pclogging.py is phValue = (rawPh/2048)*3.3*3.5+config.pHOffset
If (major assumption on my part as I can't find any gain change statement) the ADS1015 is in default gain 2 then it can only read up to 2.048 volts, so using the 11bit read (2048) divided into 3.3v looks like it is an error and should be (rawPh/2048) *2.048*3.5
config.py has pHOffset = 3.7, (initial and manually set), sensor accuracy should be better the 1pH.
SGS testHydroponicsLevel.py failed for me with a traceback statement around the location of config.pHoffset even though there is an import config statement. However I commented out pHOffset to move on and help diagnosis.
Doing the math on using 2.048v and no offset gave me the same voltage down to the millivolt as a separate ESP32 reading the PH meter directly through an A to D pin on 12 bit read.
Will make the changes to my code and see if it works, however I am also not convinced that these elements are entirely responsible for reading 14.45 in the first place.
The calculation in pclogging.py is phValue = (rawPh/2048)*3.3*3.5+config.pHOffset
If (major assumption on my part as I can't find any gain change statement) the ADS1015 is in default gain 2 then it can only read up to 2.048 volts, so using the 11bit read (2048) divided into 3.3v looks like it is an error and should be (rawPh/2048) *2.048*3.5
config.py has pHOffset = 3.7, (initial and manually set), sensor accuracy should be better the 1pH.
SGS testHydroponicsLevel.py failed for me with a traceback statement around the location of config.pHoffset even though there is an import config statement. However I commented out pHOffset to move on and help diagnosis.
Doing the math on using 2.048v and no offset gave me the same voltage down to the millivolt as a separate ESP32 reading the PH meter directly through an A to D pin on 12 bit read.
Will make the changes to my code and see if it works, however I am also not convinced that these elements are entirely responsible for reading 14.45 in the first place.
