I love sensors, and want to have tons of them spread throughout my house. I want them to all be accessible via single ui, and for my house not to be an eyesore because of them. This set of notes is me doing research into different areas of this project.
For now it’s free form, but will slowly become a more organized project over time.
Internet Of Things Protocols
Zigbee
From the wikipedia, “individual devices must have a battery life of a least 2 years to pass certification”.
There are a bunch of Zigbee libraries. It looks like the most recent, from 2017, is “Dotdot”. There’s also “Zigbee Pro” which is a differnet protocol entirely, although it can fall back to “legacy Zigbee” if needed.
- 250 kbit / s per channel in 2.4GHz band
- 40 kbit / s per channel in the 915 MHz band
- 20 kbit / s per channel in the 868 MHz band
Radio output power is typically 0-20dBm (aka 1-100mW). LoRa —- Lora.
IEEE 802.15.4
This is the physical layer and media access control layer for a lot of the IOT specifications (Zigbee, ISA100.11a, WirelessHART, MiWi, 6LoWPAN, Thread, Matter, SNAP). See the wikipedia page.
Focuses on low cost, low speed, low power.
“10-meter communications with line of sight transfer rate of 250kbit/s”.
This seems like the basis for most of IOT so I should read and understand this!
DDS
The DDS people seem to pitch it as a possible excellent solution for the internet of things. Here’s an RTI whitepaper, here’s a page from the DDS Foundation.
There’s a lot of mention of “Fog computing” which is, I guess, the layer of computers between IOT and the cloud. EG this eprosima article.
Sensors
Environment
This sensiron SEN5x is awesome. ~$35 for PM, NOx, VOC, RH, and T sensing.