Rounding errors in statusvalues about ithowifi HOT 11 OPEN

that's interesting and unexpected! The change from doubles to floats cause these rounding issues? (I cannot check this because I do not have any devices with these kind of values)

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Yep sure it can as there are some values which can't be exactly represented as float (or as double)
Only when printing a double, the print function often stops at less decimals than the resolution you can store in a double.
I think the default is 10 decimals for most string conversion functions if no nr of decimals is set.
Given you can store about 18 decimal values in a double, you need to have double values of over 1E9 (and some binary repeating fraction) before you ever encounter these issues.
With floats you can only store ~6 decimals (slightly more).

So you must do the formatting to N decimals yourself.

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The problem seems to arise because ArduinoJson uses doubles internally. Set ‘’ARDUINOJSON_USE_DOUBLE’ to 0

bblanchon/ArduinoJson#1724 (comment)

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Ok, cool stuff, I vaguely remembered something so I went to my release notes and found this:
"fix: correct rounding issues since ArduinoJSON library update"

history repeating itself but then with a different part of the code...

Ok, I would propose the following:

1. to keep the structs ithoDeviceStatus and ithoDeviceMeasurements to floats and round the values using the existing round() function to 2 (?) decimals?
   That saves 4 bytes memory per instance of the struct, which on some devies with a lot of status labels can make a substantial difference.

to change these lines:

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Statusvalues I could just round in HomeAssistant, but in settings it is quite annoying:

from ithowifi.

Also if you have similar code like this, you should add a f next to the "magic" value.

 float max = 0.0f; 

Or else there will be an extra double to float conversion in the code. (not always as the compiler sometimes can detect this behavior and optimize for it)

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I just tried master 6f5a113, sadly, it does not work as expected:

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Thanks for trying! Will look into further

from ithowifi.

Ok, cool stuff, I vaguely remembered something so I went to my release notes and found this: "fix: correct rounding issues since ArduinoJSON library update"

history repeating itself but then with a different part of the code...

Ok, I would propose the following:

1. to keep the structs ithoDeviceStatus and ithoDeviceMeasurements to floats and round the values using the existing round() function to 2 (?) decimals?
   That saves 4 bytes memory per instance of the struct, which on some devies with a lot of status labels can make a substantial difference.

to change these lines:

ithowifi/software/NRG_itho_wifi/main/IthoSystem.cpp

Lines 301 to 303 in 8ce7b87

	float cur = 0.0;
	float min = 0.0;
	float max = 0.0;

to doubles again. These would bring back the settings values to the correct values again.

my oh my @tomkooij, its even worse, sorry:
#142 (comment)

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I just tried master 6f5a113, sadly, it does not work as expected:

and I think I now what causes it:

this has to be changed to double again also of course!!

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