Getting data produced by IoT sensors into a database is practically a mandatory step before effective visualisation (eg dashboards).
This recipe shows you how to get an MQTT payload into an InfluxDB database using three Node-Red nodes. It makes the following assumptions:
A work in progress collection of proprietary and as of yet undocumented HomeKit characteristics and their UUIDs used by Elgato Eve.
Based on the work by gomfunkel and 0ff. Characteristics and data dump for Door, Motion and Thermo thanks to @NebzHB.
More infos not yet incorporated in the comment section.
This list is not including all Eve accessories available and some services and characteristics still make no sense to me. If you have anything to contribute, please leave a comment. There is no guarantee that the information listed below is correct.
On my RetroPie machine I wanted a hardware volume knob — the games I play use a handful of emulators, and there's no unified software interface for controlling the volume. The speakers I got for my cabinet are great, but don't have their own hardware volume knob. So with a bunch of googling and trial and error, I figured out what I need to pull this off: a rotary encoder and a daemon that listens for the signals it sends.
A rotary encoder is like the standard potentiometer (i.e., analog volume knob) we all know, except (a) you can keep turning it in either direction for as long as you want, and thus (b) it talks to the RPi differently than a potentiometer would.
I picked up this one from Adafruit, but there are plenty others available. This rotary encoder also lets you push the knob in and treats that like a button press, so I figured that would be useful for toggling mute on and off.
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Simple guide for setting up OTG modes on the Raspberry Pi Zero - By Andrew Mulholland (gbaman).
The Raspberry Pi Zero (and model A and A+) support USB On The Go, given the processor is connected directly to the USB port, unlike on the B, B+ or Pi 2 B, which goes via a USB hub.
Because of this, if setup to, the Pi can act as a USB slave instead, providing virtual serial (a terminal), virtual ethernet, virtual mass storage device (pendrive) or even other virtual devices like HID, MIDI, or act as a virtual webcam!
It is important to note that, although the model A and A+ can support being a USB slave, they are missing the ID pin (is tied to ground internally) so are unable to dynamically switch between USB master/slave mode. As such, they default to USB master mode. There is no easy way to change this right now.
It is also important to note, that a USB to UART serial adapter is not needed for any of these guides, as may be documented elsewhere across the int
| # rtl_fm demodulation guide | |
| # based on excerpts from: http://kmkeen.com/rtl-demod-guide/index.html | |
| # requires rtl-sdr (rtl_fm bundled), sox for audio, multimon for pager decoding | |
| # broadcast FM radio | |
| rtl_fm -W -f 89.1M | play -r 32k -t raw -e signed-integer -b 16 -c 1 -V1 - | |
| # police scanner | |
| rtl_fm -N -E -f 154.42M -f 154.75M -f 154.82M -f 154.89M -s 12k -o 4 -g 49.2 -l 70 | play -r 12k ... |