# EmonTx - use of EEPROM

**URL:** <https://community.openenergymonitor.org/t/emontx-use-of-eeprom/9083>\
**Category:** Labs\
**Tags:** emontx\
**Created:** [6 November 2018 15:05 UTC](https://community.openenergymonitor.org/t/emontx-use-of-eeprom/9083 "2018-11-06T15:05:55Z")\
**Posts on this page:** 1\
**Showing post:** 13

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**Author:** ![Greebo](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/greebo/32/4556_2.png) [@Greebo](https://community.openenergymonitor.org/u/Greebo)\
**Post date:** [6 November 2018 22:47 UTC](https://community.openenergymonitor.org/t/emontx-use-of-eeprom/9083/13 "2018-11-06T22:47:38Z")

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> [@Update to 3-Phase PLL sketch](https://community.openenergymonitor.org/t/update-to-3-phase-pll-sketch/8610/20):
>
> The question here is… What on earth is ‘nan’ representing??

That output comes from the [config.ino file here](https://github.com/openenergymonitor/emontx-3phase/blob/master/src/config.ino#L89-L101)  
So the “nan” you are seeing is a direct result of `Serial.println()` trying to print those float memory locations that do not contain float values. The relevant EEPROM locations may in actual fact contain `0xFF`’s but because the first byte of EEPROM did NOT contain `0xFF`, the remainder of the values were assumed to be appropriate.

The relevant bits of code are line 48 and the section from lines 55 down to 75 here:

> <https://github.com/openenergymonitor/emontx-3phase/blob/fca9f386e72c6cbab6493bb6492cb0634a2ed360/src/config.ino#L48-L77>

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