[GTALUG] Serial logging: best practice, pitfalls, advice?

[Bill Thanis]

I would make the logging as easy for a computer program to parse while
still making it readable.

Bill


On Mon, Sep 15, 2014 at 11:25 PM, Stewart C. Russell <scruss at gmail.com>
wrote:

>  Hi,
>
> Since there are some really experienced system people here, I'd like to
> ask some advice on designing logging parameters for a serial device. I'd
> like to design the output log so it's most obvious to users what's coming
> out the thing, and so it's easy to stuff readings into a database for later
> analysis. I have complete freedom to redesign the log coming out of this
> embedded device.
>
> Here's what I get from the device:
>
>    1. Approximately twice a minute, I get a cumulative energy reading and
>    the average power for the last 30s or so
>    2. About once every five minutes, I get a packet which contains an
>    approximate (±1°C or so) ambient temperature
>
> I can also report:
>
>    - a fairly accurate (at least over the short term) elapsed time stamp
>    in milliseconds - but not real time, as there is no RTC. The time stamp
>    rolls over slightly more than once a month.
>     - the received signal strength in dBm
>
> This device is decoding the RF packets from the BlueLine Power Cost Meter
> that the OPA and local utilities give out to hydro consumers in Ontario.
> It's also the same as the Black & Decker Power Meter. The device would
> allow you to track real-time energy consumption without fiddling around
> with Toronto Hydro's time-of-use website (or, gulp, having to mess with
> Green Button energy files - eek!). As it counts the hydro meter's watt-hour
> pulses, it's pretty accurate.
>
> So - I'm currently logging something like this
>
>     [105874810] Energy: 63856 Wh, Power: 613 W, Temp: 14 C (Rssi -81 dBm)
>
> where the first number's the timestamp.
>
>    - Would this format cause hiccups in typical logging applications?
>    - Is 9600 baud still the gold standard serial speed? I can use pretty
>    much any speed, and there's never much data to transmit.
>
> Any suggestions/questions greatly appreciated.
>  If anyone has one of these OPA Power Cost Meters, and wants to have a
> play with it, you'll need:
>
>    - a 3.3 V Arduino (or a standard 5V one and some level converters that
>    can do SPI)
>    - an RFM69 433.92 MHz transceiver board (caution: it uses 2 mm pin
>    spacing, so won't fit a standard breadboard)
>    - this code: https://github.com/CapnBry/Powermon433
>
> The output is rough, but I've successfully tracked several days' power use
> so far with far higher resolution than is available from smart meter
> website.
>
> cheers,
>  Stewart
>
>
>
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