[OpenTRV-dev] I just added this to the data sets doc...

[Bo Herrmannsen]

btw... and not related to JSON... but could a time stamp of some sorts be
put in so that one unit can be the master clock for the others?

Since my unit at the hotwater cylinder is mains powered and the rest on
battery it would be nice to just replace battery and they listen for the
time from the DHW unit...

just a quick thought

2015-06-23 10:12 GMT+02:00 Damon Hart-Davis <dhd at exnet.com>:

> Hi Y’All,
>
> Bruno and I were having a discussion yesterday afternoon about how
> properly to represent for *JSON* transmission values with units that can be
> automatically translated to SenML/UCUM units, that are easy for an MCU to
> generate (eg no floating point if possible), that remain human readable and
> reasonably compact, and that deal with values whose natural representation
> is with some power-of-2 multiplier to capture all the significant (binary)
> digits with minimal bloat in the decimal int expansion.
>
>
> http://www.earth.org.uk/note-on-IoT-data-sets-and-processing.html#binshiftrep
>
> Any thoughts?
>
> Rgds
>
> Damon
>
>
> 2015/06/22:
> Bruno and Damon discussed the desirability of completely mechanical
> conversions
> from JSON sensor units to UCUM/SenML units to minimise or eliminate magic
> 'mappings' that require sophisticated developer time (in line with IBM
> suggestions).  One particular issue that cam eup is being able to represent
> value as integers (for brevity and to keep code small on the sensors)
> and scale to integers for transit, when the natural scaling is a power of
> two,
> eg temperatures from common sensors with four significant bits after the
> binary
> point, ie that are currently being sent with units <code>|C16</code> for
> "Celsius times 16".  Bruno was going to investigate.  One possible escape
> hatch is with the Ki/Mi/Gi/Ti "special prefix symbols for powers of 2".
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