Best posts made by wallyllama

Finding things to make into cases is fun. Here is my raspberry pi.

@ŕähûł-śïñģh if you are successful you'll be rich. There are simple detectors like pir, and complex like cameras with computer vision software. Im working with amg8832 chips with 8x8 grid of temp sensors, essentially a low res camera. I looked at radar "pir" modules and thought modulating the voltage would give data that can be processed, again complex, combining pir and ir door sensors has been suggested. None of this is my original idea, im just trying to piece something together.

Most important:
Community is helpful and enthusiatic
Open source/hardware
Doesnt use the cloud (unless you choose to)

Nice to have:
Mature enough to be usable
Wide hardware support, with ability add new
Uses inexpensive commodity hardware

Siesmometer?
http://www.instructables.com/id/This-Seismometer-is-no-toy/step2/Seismometer-seismograph-System-Components/

https://www.sparkfun.com/news/2074

https://www.sparkfun.com/tutorials/235

The idea is good, but I have seen posts from at least 3 continents, so getting people online at the same time is difficult. IRC^h^h^hslack has a nice immediate quality, forums are less ephemeral, and easier to search and understand later, and for newcomers.

There is good in both, if you really want a chat like forum, it will take more time and effort. Maybe work with the creator of mysensors (that is @hek, right?) to see if there is a slack plugin for the website, or try some events in slack, etc.

https://www.maximintegrated.com/en/app-notes/index.mvp/id/148

Here is maxim's guide on wiring for 1-wire. There are a few things to note, one is the "weight" of each sensor's cable. Read that section closely. Another is hubs. Hubs are basically a 1 wire switch that connects each segement of the network 1 at a time, so you can essentially walk though each ray of your star. The third is the suggestion above to use multiple pins on the arduino and just make several simpler networks.

Some things about the direction sensor, your magnet/reed switch is exactly what is in the old dallas 1-wire weather station and it worked well giving 16 positions,

the led/photodiode method mentioed by gohan is interesting, if you used analog inputs you could use the value across 3 of them at a time to interpolate a pretty high resolution answer, multiplexing could make it so you dont need 8 analog inputs.

Another thing is a rotary encoder, ive seen them used to measure the angles of telescope mounts, i believe they can be had with good enough resolution for your needs.

I didnt read the whole thread, apologies if i am repeating ideas, or if you have decided on a solution.

In the days of analog tv/radio dead spots and multipath were easy to detect. Digital isnt as susceptable to multipath, but isn't completely immune either. An rf field meter might help. Directional antennas probably will help. If these nrf devices can measure rssi it may be good to hook up and led as a signal quality indicator of some sort. It sounds like you have a strong signal near the problem, could be overloading the receiver, could be IM ( intermodulation, not instant messaging). It could be an rf shield on all but the antenna may help.

My sensors may have some of this already, if so ignore me, Im using rs485.

Note to self, check if "myactuators.org" is available.

Filter caps on the actuators? I think someone mentioned this, they can be a source of noise in the power, or rf hashing.

An rtl_sdr sort of device might be a cheap rf signal analyser.

Is it any 5th temp sensor? In other words could it be a bad temp sensor? Also 1-wire doesnt like 'star' wiring, are all the sensors wired with short connections to the main cable? More like ,, and less |_| and for sure not |/

@Samuel235 here is a link to the video. It was impressive. Im not going to advertise for the company, but you can find them withnsome simple searches.

https://www.thisoldhouse.com/how-to/future-house-smarter-home-electrical-metering

@NeverDie nice! Sparkfun has a breakout that is 20% cheaper than just the omron sensor. This is is getting closer to my price range, the radar modules are cheap and might be fun, but this would likely yield a working solution sooner.

I came across this library that claims collision detection and multiple masters for rs485. It uses hardware serial, which seems to be less favorable among people using rs485 and mysensors.

It seems unlikely I am the first to find this so I'm wondering if anyone tried integrating this with mysensors? Was it rejected? Or found to be too big? Or oherwise inadequate?

https://github.com/MichaelJonker/HardwareSerialRS485/wiki/software-capabilities

Short answer about the additional components is yes. The datasheet has a recommended circuit and about 1/2 the parts listed are noted as required.

@NeverDie no it was an amg8833 breakout and at adafruit not sparkfun sorry, $39us. Mouser and digikey have just the sensor form$22us in small quantities.

https://www.adafruit.com/product/3538

@gohan this is exactly why i brought up j1708, it is a hardware spec(can be any software on top), that uses max485 chips, you drive the de line instead of tx and it allows you to "see" collisions on the line. It would need a layer that does retransmits, but i dont see why the mysensors rs485 code clouldnt ride on top of that. There is an id that is utransmitted first that all nodes have to watch for which is duplicated efforst as the mysensors layer has that.

I see it like this pseudo code:

All nodes listen for an id,
if none, then start transmitting,
watching for dominant bits in between bits that hint someone else is transmitting, if collision back off for random time.
if no collision transmit full message as normal mysensors message
Other nodes must listen until message ends then they can start a transmit after random interval.

The secret is really in tying tx (it looks like) low and control de, re is enables always so you can see other bits. Once a node has the bus, everyone shuts up until it is done. You only decides "who has the floor" and how to know when they relinquish it.

J1708 is 9600 baud, which may be ok, but ill bet it would work at higher speeds.

I think most of the problems could be overcome, but they will take time and effort, which would take away from other projects unless a volunteer comes forward. Im not ready for something like this yet, so I should propbably keep my mouth shut.

The amg8833 has an 8x8 grid, and a 60° field of view, so if you have 8' (2.4m) ceiling that will cover a square with 14' (4m) sides at the floor. One pixel will be about 1' 9" ( 44cm) at the floor. That should be plenty of resolution even without interpolation. I suspect interpolation could give an effective grid of 16x16 at least, maybe more.

Careful planning and mounting in a corner or on a wall would have some trade offs, but might allow for covering a larger area with one sensor.

One trade off is identification. Is that heat blob a person or @gohan 's cat? That might be doable, but is it Mom or Dad, or teenager would probably need supplemental information.

Stationary heat sources, lamps, vents etc, could be filtered out, in probably several different ways. I have some large windows that may blur the data, but this isnwhere situational awareness wouldmc9me in. E.g. if (curtains == open && tod == daytime) then apply filter to pixels x through z, maybe time of year etc.

Other obstacles would probably look like cold spots and unless they are large wouldn't affect detection of people. They might dim a bit, so maybe a filter would be needed here.

This is quite doable. I've been thinking about it for a while and seeing usable sensors for effectivley 1/2 price has me a bit excited. I appologize if I have monopolized the podium a bit.

Is the fact you didnt get it working an OOPic failure? (Not really a comment on what was and probably still is a difficult project, I just cant resist puns)

@NeverDie data sheet says 7 meters max, there is probably enough margin, at least for typical room sizes in the US. I think the 60° fov will be the bigger issue, getting coverage. Imagine you place the sensor in the center of your ceiling. The room is square, 14ft on a side and 8 ft high (~4X2.4 M), the sensors field of view would exactly cover the floor, but it is shaped like a pyramid with the sensor at the peak, so if you stand flat against a wall, only your feet would be in view.

@gohan's suggestion of bluetooth tags doesnt have that problem, it can be seen anywhere the signal gets to. You can have multiple detectors for coverage and triangulation. If you have a smartwatch or phone you always carry then youndont even need a separate tag. It is relatively cheap and simple, and most of the tech is done already.

(Now here is where I loop around and start spinning in circles) I dont want to have to carry anything, it should be possible to detect my presence by all the signals bouncing off me already, like light, or ir, or wifi, or radar, then the googling happens......

@constantine-poltyrev i dont have code yet. I havent really started on software yet. My thinking is to start by using the adafruit code as a base, set up the sensor in a likely spot and modify the code to stream data to a pc or r-pi, maybe with a web cam next to it for comparison. Id look to see if there are patterns visually that are helpful, but my real hope is that since the pixels are temperatures, the ones with people are at people temperature, so around 37°c.

Maybe the first filter would call out pixels in the 35-40 degree range, and send 0 for the rest. If that gives a spot that has few false readings it may be good enough for "there is at least one human present" or not readings. A glorified pir.

Likely though a person will be more than 1 pixel, or worse part of more than one pixel, how to know if two cooler pixels represent 1/2 a person each, then there is the problem of the sun heating something to human temperature. My gut feeling is these are simple enough that existing solutions can be adapted. I dont know what those are yet, maybe bayesian filters, maybe some sort of computer vision.

A hardware product called openmv may provide some inspiration. It uses something called micropython and opencv. With 64 pixels we have a simplifies case, but I think an arduino is not going to be enough, a raspberry pi or maybe a nanopi neo should be sufficient.

I think that is the current contents of my brain on this, experiments are the next step. Starting with streaming some data and looking at it.

@sam9s what you are describing, while a nice way to control things, has the same basic flaw as a PIR device. You have to tell it you are there. The PIR(alexa) knows what room it is in, but you have to signal it some how. Alexa is signaled by a voice command, PIR by motion, but if you are quietly reading a book both of them forget you are there. Alternatively you can have them assume you are there for a set amount of time after the signal, or until they get an off signal.

The trick is to get them to detect you without actively addressing them. If Alexa can detect breathing, or heat or CO2, etc, then it would solve the problem.

you can combine alexa with door sensors. If alexa is triggered and no one has left the room then someone is still here. That is the idea that @dbemowsk pointed out earlier in the thread.

TL;DR. To me the history of computing is the story of centralizng vs. decentralizing. As a "peripheral" becomes more powerful it becomes a center, that is then decentralized from....

Centralized

Pros
cheap at the edge, center can more easily share resources (economy of scale), one upgrade can improve the whole system.

Cons
edge is less flexible, sharing resources can lead to contention, center is more complex and possibly harder to troubleshoot. Probably more wires between edge and center.

Decentralized

Pros
nodes are more flexible and easily adapted and customized to the location, smart nodes can respond faster as it doesnt have to travel all the way to the center, wait for attention, then go back (like reflexes, they only have to travel to the spune, not to the brain). A single failure is less likely to take down the whole system. Can probably use radio in place of wires.

Cons
probably more expensive overall, more points of failure, network to center is probably more complicated, required better wiring.

My personal preference is hierarchical. I like nodes that can operate independantly if disconnected, hubs that aggregate and do some processing (like a spine), and a center that has the big view and uses all the inputs to make big decisions. Call me biased if you will, but it is just the way I am made. :c

Side note. I did a quick search, there is a cec library for arduino!
https://github.com/stefslon/cec-arduino

I'm going to go a bit conceptual here, riffing on some ideas that I believe I got from @dbemowsk. A multi-pronged approach may be useful here, maybe bt for the car and bicycle, amount of time since any PIR device triggered, time of day, etc. Then using the "smarts" of a smarthome a reasonable estimate of home/away can be gained.

I dont think an A.I. like the googazon has is required, but something smarter than a single node might be apropriate.

I know WAF is not a joking matter, but I immediately heard Greg Kihn sing, " my WAf's in jeopardy, baby".