Is there a table somewhere of which devices support which traits? I'm particularly interested in humidity:
https://developers.google.com/nest/device-access/traits/device/humidity
But temp would be cool too, and I can convince myself ~most smart devices would have some awareness of temperature to shut down before they overheat etc.
I suspect humidity is just in the thermostats (not suitable for how we do HVAC here in AU) but I'm holding out hope it might also be in the smoke detectors... although they're not listed on the devices page. Even under the old API it looks like they didn't offer much (for example, it'd be awesome if you could get the motion detector state, or last motion detector trigger event from the nightlight feature).
Has anyone played around with the API enough to know? I'm only really interested in temp and humidity on the current list, so don't want to shell out the registration fee if they're not going to be available on my doorbell + smoke detectors + home hub.
The Device Access docs don't list devices per trait, but they do list traits per device:
Camera
Thermostat
Doorbell
Display
Today the only device type supporting the Humidity trait is Thermostats.
Related
My professor recently approved our research paper which will also be used in our final year thesis. Basically our main purpose is to create a system for location tracking and attendance automation for students and staffs. We would like to use the power of bluetooth low energy modules for this project.
I have actually done quite few research about this but I am having trouble which keywords to use in order for me to filter the right answers for my question. So instead, I'll just put all my questions here.
I provided an image to further understand the concept I am talking about.
Basically, the broadcaster/advertisement mode modules are for students and staffs. While the observer mode modules are initially installed in every rooms or spaces in our building/campus.
Broadcast and Observer mode
I would like to clarify first that the location tracking is only basic, it only detects which rooms are the students and staffs located.
Here are my questions:
What is the maximum advertisement/broadcaster module can the observer module detects at the same time?
Our target is about 50 students per room, 300 students in cafeteria, will the observer module have a large amount of latency upon scanning advertisement packets?
Do we have to use different module for observer mode, or will the same module for broadcaster mode be just fine?
Since this is supposedly embedded to school IDs, we would like to use a coin cell battery, how long will it last?
According to my research, BLE range is about 100 meters, but we will be using coin cell battery, is it really possible to achieve 100m for broadcasting and observing? If it is, can we perhaps decrease it by programming?
My apologies for too much question, as this is actually our first time doing applied hardware stuffs due to pandemic. Most of our laboratories are basically tinkercad base. Face-to-face classes are allowed for only medical students for now.
A few answers:
BLE scanners can detect hundreds of distinct broadcasters at the same time. There is no hard limit, but the more broadcasters the longer it will take the scanners to detect each broadcaster.
Most BLE modules support both peripheral mode (broadcaster) and central mode (scanner) simultaneously.
Scanning 50 broadcasters in a single room will easily detect 90% of packets, so if the advertiser is going at 1 Hz it will usually take one second to detect, but sometimes 2-3 seconds of packets are missed.
The indoor range is closer to 40 meters with no walls obstructing the signal. Outdoors with clear line of sight the range is higher. Walls often block signals almost entirely, depending on materials.
A CR2032 coin cell can power a BLE broadcast at 1 Hz and max power for about 30 days.
Creating an embedded solution is cool and valid but just remember that broadcasters already exists as each and every student carries a smartphone with BLE embedded into it and your observer can be any BLE capable device from smartphone through PC with BLE dongle all the way to Arduino and alike.
Your broadcasters (or BLE peripherals as they should be called) will need an Android / iOS app and you will have to deal with working in the background without the operating system stopping your app.
Your observer (or Central in BLE language) can be any stationary PC if such exists in the class which can make development and deployment a lot easier.
Is there an off-the-shelf beacon I can just buy that also has support for triggering Vibration / Haptic Motor over BLE? Amazon / whatever links are welcome.
Context: I'd like to trigger vibration from iOS in a small independent device. BLE seems ideal as I need to support more than one and all devices should be within range. I'm trying to rapidly prototype something instead of cranking out my own HW.
For prototyping you may be able to use a few sub-$20 Xiaomi Mi Band devices (or Band 2 which should be under $30 and has a screen). And then use API like this to trigger vibration: https://github.com/betomaluje/Mi-Band
They both can be removed from the wristband and look like a 2 cm long pill, and last weeks on a charge with normal use, maybe months when not counting steps.
I have several Microsoft bands, to be used as part of a group health initiative. I intend to develop a single app on a tablet which will pull the data from the bands. This will be a manual process, there will not be a constant connection to the tablet and no connection to Microsoft Health.
Does anyone know if this is possible?
Thanks
Emma
The general answer is no: Historical sensor values are not stored or buffered on the Band itself.
It does however depend on what sensors you are interested in. The sensor values are not buffered, so you can only read the current (realtime) value of the sensors.
But sensors such as pedometer and distance are incrementing over time, so these values will make sense even though you are only connected once in a while. Whereas for, e.g., the heart rate and skin temperature, you will only get the current (realtime) value.
So it depends on your use case.
Can anyone tell me what major and minor (contained within the advertisement packet of BLE signals) are used for? I've heard that it's used for differentiating signals with the same UUID, but that raises questions like "why use two" and "is that just how certain receivers use it". It would be useful to have a decent explanation of it.
As per #Larme's comment, I presume you are asking about iBeacon advertisements - these are a special use of BLE. Bluetooth Low Energy service advertisements have a different format and don't include the major/minor.
The iBeacon specification doesn't say how to use major and minor - this is defined by the people that implement solutions using iBeacon. Two numbers just gives more flexibility.
A lot of effort went into making BLE use very little power. Accordingly the iBeacon advertisement has to be quite small in order to minimise the transmission time. I guess the designers decided two 16 bit numbers was a reasonable compromise between power consumption and a useable amount of information.
A typical retail use case could use the major to indicate a store (New York, Chicago, London etc) and the minor to indicate the department (shoes, menswear etc). The app that detects a beacon can then pass this information to a server which can send back relevant information - the user's location on a map or specials for that department etc. This was discussed in the guide that #Larme linked to.
A solution that presented information on museum exhibits might just use the major number to determine which exhibit the person was near and ignore the minor number. The minor number would still be in the advertisement, of course, the app just wouldn't use it for anything.
I have a friend who is working on a project where they need to deploy a large number of devices over the midwest. For simplicity let's say these are temperature gauges - they read the current temperature and transmit that information to a server. The server would just need to know what device is reporting what temperature (412X|10c).
These devices will be in forests, near highways, in cities and swamps. All other technology is prototyped and working (ability to read the temperature, the hardware for the device) the open question they have right now is 'what is the cheapest way we can send this information to the primary server'?
I think they'll need to go with a wireless carrier (verizon/sprint/at&t) and use something similar to mobile broadband. Is there really any other option?
You could do it with ham radio and something like APRS, assuming they don't care about encryption and don't have a pecuniary interest in the project.
You wouldn't need full mobile broadband, as your data would fit in a text message. You can get cellular shields for arduino that would probably fit your needs.