20
A general process of microcontroller selection.
Sum up your requirements towards the microcontroller. For example in this case:
1 hardware timer, to measure time between trigger and echo pulses.
2 GPIO pins to interface the sensor Echo and Trigger pins.
Possibly UART to interface the RF communication module.
1 ADC input to monitor the battery voltage.
You ...
17
In as much as there is a 'standard' solution I suspect it's going to look like a Wi-Fi enabled microcontroller attached to a relay or MOSFET. Something somewhere has to be on 24/7 if you want round-the-clock control over your outlets.
I've made a bunch of internet controlled sockets using ESP8266 ESP-01S modules (not the ESP-01, which has less memory) and ...
16
You can hook up a USB battery pack to both the Pi and the charger (as long as it is designed to charge while being used) and if the power goes out the USB battery pack will take over powering the Pi directly.
Search for "USB UPS" and you will find tons of info on individual setups.
16
I have been a university tutor in a department that now teaches IoT and your observations are right when it comes to getting your hands dirty with some toys rather than just a degree. A lot of computer scientists work in collaboration with engineers such as communication engineers, production engineers to come up with unique solutions where IoT becomes an ...
15
You can use a spectrum analyzer to make sure that:
The antenna is emitting at the correct frequency (range).
The output power is the expected (theoretically calculated) output power (or it is close enough).
A higher end version of a spectrum analyzer (including bit error rate analyzer) could help you further on making sure that not only the antenna but ...
15
Orange Pi Zero is cheap (7$ + shipping), can be hacked to run on passive PoE, supports TCP/UDP over on-board ethernet and wireless and has a few I/Os.
It's not exactly a microcontroller in my book, it's more like a small headless linux computer, but then you mention raspberrypi zero as a reference which is in the same class.
When using it, be sure to use ...
14
This is a very broad question, but I will try to give a few general pointers, hopefully useful to others, as well as you (so, please accept my apologies if I post things which you already know).
If you are asking about reading sensors, this is telemetry and not necessarily IoT. I have coded many projects where a standalone PC reads and displays some ...
14
The model that IoT Hub connected devices use is that they will never accept incoming connections. IoT Hub devices never act as a 'server', and this is a crucial part of the security model in Azure IoT. The definitive model on this is encapsulated in Clemens Vasters' 'Service Assisted Communication'.
Therefore devices are always 'polling' an external service ...
13
A Raspberry Pi 3 is a pretty serious bit of kit when you think about it
Quad core Arm Cortex
1gb of RAM
a onboard GPU
That is a huge amount of memory, easily more than enough to run a MQTT broker and something like Node-RED to interface between a LoRa radio and the broker.
We have a commercial gateway (MultiTech MultiConnect Conduit) in the office which ...
11
There are two main approaches to characterising an antenna and its effectiveness in-system, free space and in-situ. The first will give you a best-case baseline, is less susceptible to measurement noise (especially if you have access to a large anechoic chamber), and probably works best for selecting between candidate antenna variations. In-situ measurements ...
11
The IKEA Trådfri lighting system is all CoAP based, you can find my write up on the protocol here
Belkin WeMo devices are all uPnP and SOAP controlled as well so another open/self describing protocol
10
Which microcontroller and programming language should I use for an Internet-enabled weather display?
The Onion Omega 2 claims to be the smallest Linux computer in the world. That claim may not quite be true (see the vocore2 below, for example) but in my experience it's got to be in the smallest 3. Costs only $5, built-in wifi, designed with IoT specifically in mind. Has a few shields available on their web site. Brand new product, seems to have a strong and ...
10
You do not need PoE for your setup. Just use two wires from Ethernet cable to power your controllers.
Ethernet cables have four unused wires: 4 (blue), 5 (white with blue), 7 (white with brown) and 8 (brown). For personal use, I believe, you can use these wires for powering up your micro controllers. Of course, you should take precautionary measures in case ...
10
I think it's non-existent today.
I work at a Dutch municipality and, though things might have changed now, in December 2017 our environmental department concluded that even semi-professional gas or dust sensors were just not good enough to determine the low levels needed for outdoor measurements. (Including everything Libelium offered at that time for CO, ...
9
As an experienced developer you have the ability to understand logic, read and write code, figure things out, and some other important skills. What you probably don't have is an understanding of basic electronics and the art of getting code from your desktop running on a small device.
Jumping in at the wrong level of complexity can be daunting, and may mean ...
9
If possible choose a device that has a built in battery. A few such examples that use the common 2-pin JST connector. The first two are based off of the esp8266
WioLink
WioNode
C.H.I.P ($9 computer)
Raspberry Pi Zero + battery module
9
Electronics are generally recyclable, that is not something specific to IoT devices. More specifically, your IoT device will typically provide a general purpose MCU.
Recycling an MCU is generally feasible. Even if the bootloader is locked down, you may be able to wipe the entire device using JTAG. It is debatable how much value there is in re-using a ...
9
This is widely discussed over the net, but, those are different things. Which one is better, it will depend on what you're building.
My way of choice is:
If I want device that reads a sensor and display the data and send it to a webservice, get an arduino (or much better, a ESP8266 or equal device that already have WiFi)
If I want (one or more of this) to ...
8
In order to properly test the antenna at minimum the following items are required
A source antenna with the known pattern and transmitter such as a RF signal generator create known signals
The test antenna with a receiver system measure and monitor the receive RF signal. In this case the z-wave device could be used receiver system.
Antenna under test (AUT) ...
8
By far the easiest route is to buy an exisiting product here which is sufficiently open that you can use a standard RF module to control them.
This is equivalent to having an MCU and switch integrated (so gives you good autonomy) and also avoids any problems with the appearance or safety of the result. You are of course then stuck with the manuracturer's ...
8
Arduino do a board with built in PoE, but at double the price of a Pi last time I looked, I would not consider it cheap. And sounds physically bigger than you are looking for.
The is also the Arduino Yun with poe, but that costs even more
If a pi Zero W will do what you want you can get PoE adapters for of the order of £8 each singularly, possibly cheaper ...
8
I'll assume that the processing requirements on the device are near enough zero. It sounds like you're using some acceleration input to determine how often to wake up the GSM device.
Ideally, you want an MCU which can be triggered from the accelerometer to wake from sleep, and then determine when to send a location ping. Any micro-python based device should ...
8
There are a lot of devices out there that allow you to control digital I/O over a network. The difference between this and relay control is very little as you can very easily add a Solid State Relay to a digital output.
Products in this space can vary from hobbyist to home to industrial.
When selecting, there are some other things you should consider when ...
8
The generics first
Some of the candidates only talk about what they learned from building PCs
Coming from PCs is not a problem, but, candidate should understand that an IoT device/product/application isn't same as a general PC.
PC are built for general compute purpose, you can use a PC for almost anything:
Browse Internet
Play games loaded with ...
7
If you want a totally independent switch in case of the microcontroller fails, then you can hook-up an XOR gate for two inputs. The relay will be off when both inputs are the same, and on if the inputs are different. The two inputs are:
Regular switch for manual control.
Output from an MCU for automatic or remote control.
The circuit:
Normally the switch ...
7
This open source Raspberry PI Alexa client has support for free wake words made as easily from PI's terminal as:
sudo systemctl stop AlexaPi.service
sudo nano /etc/opt/AlexaPi/config.yaml
change line:
phrase: "alexa"
See discussion.
7
IoT runs the gamut of computing, and covers a huge range of technologies, implementations, and tactics. The nutshell is that it just means things are connected to a comms channel, e.g., the internet. Understanding how things connect to things is probably the key: messaging, eventing, streams.
I'd grab a few small devices, doesn't matter what they are, but ...
7
The Internet of Things is huge. It consists not only of the computer science behind it, but also of household applications such as the Google Home, etc. If you end up going into sales, knowing something about available devices could be helpful.
I personally recommend a few things:
1. Subscribe to good magazines.
There are tons of magazines and up-to-date ...
7
Building your own device for this use case really is the wrong approach.
The industrial design to build something that will survive day to day use and be comfortable to wear with a useable battery life is likely to take longer than the study you want to run.
Just buy an off the shelf fitness tracker. There are plenty that have open BLE interfaces.
But if ...
7
Building on Helmar's answer I would suggest a DIY solution: a miniaturized reed switch and a magnetized / magnet attached deadbolt.
Check if there is place for a miniaturized reed switch within the strike plate with the deadbolt fully extended. Those switches come in packages as small as 2 mm diamater and about 10..15 mm long. Since they actually come with ...
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