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40

2.4 GHz is one of the industrial, scientific and medical (ISM) radio bands. ISM bands are unlicensed, which makes it easier to certify the equipment with FCC (or its counterparts in other countries). However, what special about 2.4 GHz? There is about a dozen ISM bands. Some at higher frequency, others have lower frequency. Not all ISM bands are ...


26

The "special" thing about 2.4GHz is that when spectrum was allocated for various needs in the 60's and 70's, no one wanted it, because it was thought that atmospheric water absorption made it useless.


22

CAN sounds the most applicable in this case. The distances inside a house can be handled by CAN at 500 kbits/s, which sounds like plenty of bandwidth for your needs. The last node can be a off the shelf USB to CAN interface. That allows software in the computer to send CAN messages and see all the messages on the bus. The rest is software if you want to ...


13

It is 'special' since it does not go very far. Strangely, this turns out to be an important advantage as many devices and people can use the same band in near by area without interference. Tele density is the term used in phone industry as how many cordless phone per square mile. Early generations (25 years ago) coreless phone use few MHz and tens of MHz ...


9

I would suggest two options. First - and this involves a small amount of wiring and soldering - using a PowerSwitchTail II. This is a very safe way of switching mains voltage. There is adequate isolation, it is safely cased and tested. If you really want to do no wiring or soldering at all, then I would suggest finding one of the common 434/868/915MHz (...


9

The rule of thumb a lot of people use is that lower frequencies will have better "penetration" than higher frequencies. That's true in some cases, but not all. This is probably derived from calculating skin depth of materials. The skin depth is just how deeply into a material an electromagnetic wave of a particular frequency can penetrate. The equation used ...


8

This is how you control a relay. A relay gives you proper isolation from the mains, and with the appropriate relay you'll be able to switch more than a kW at 230V. The relay will need more current than the Arduino can supply. That's where transistor Q1 comes in. The transistor multiplies the input current from the Arduino (the "on/off" at the left) by ...


7

How about this: You connect a 5V power supply, and the 4 inputs to 4 of your Arduino's outputs, and you're done. USD 16.50.


7

Because the light link specifications haven been released yet, except for members of ZigBee alliance I don't think you will be able to at this moment. Unless you want to become a member of the Zigbee alliance. I have had contact with one of their developers who said that modules that where able to use previous specifications should also be able to use the ...


7

In Europe, you would have to comply with EN300220 which is an ETSI standard. If you use a library for the MAC layer of Zigbee, this will have been done for you, but if you write your own MAC layer, you have to take care of all the restrictions in this document yourself, and then get a test house to validate your product according to the telecomms regulations....


6

I don't think you really understand what you are talking about here. "Zigbee", or IEEE 802.15.4, is a protocol. As such, it has no "programming language". Theoretically, it's completely possible to implement a system which can handle the zigbee protocol in any programming language, assuming that whatever language you're using has adequate hardware support ...


6

My answer here may help: The appropriate code (Arduino) of Xbee Once you have one master and one slave like in that answer, repeat the slave configuration steps for the second slave. Then: To send from slave to master, just send the data. To send from master to a slave, set the master's DH and DL to the slave's SH and SL respectively, then exit command ...


6

I would recommend controller with CAN as this feature are meant exactly for the controller networking purpose. RS232 can be implemented easily but it will get real challenging if you try to implement communication more than 2 nodes (cause it's not build for this purpose). Ethernet can be a sweet option too since you mentioned some host and clients ...


6

According to the product details, the output impedance is 100kΩ, so 100Ω would almost completely short the signal. To get 1.2V from 3V, you need a ratio of 1.2 / 3 = 0.4 Assuming a steady 100kΩ output impedance, you will need a single 66.6kΩ resistor from the sensors output to ground to divide the range down as necessary: 3V * (66....


6

I am sorry to be the bearer of bad news! There are a few things that stand out. In addition, even after these problems are corrected, there's still going to be a lot of learning and analysis to do. Please don't take my suggestions as criticism; RF is tricky :) Also, there have been hundreds of books written on RF. I can tell you some things to look for, but ...


5

Music is a special case for audio latency. For speaking, or voice conversations you can have up to 100mS latency before it impedes the conversation - though it can be noticeable at that latency. Music, however, has a beat and 100mS is unacceptable. When musicians play together acoustically sound travels about 3mS/meter. On a typical stage setup band ...


5

Some of the reason is cost (both financial and power budget with distance), some is because what frequencies are reserved for other types of devices/communications and the interference caused by such deviations from those frequencies. When a frequency is chosen for widespread use, it is cheaper to use off-the-shelf parts in your design rather than having to ...


5

ZigBee (and more generally 802.15.4) targets different uses compared to WiFi (control vs data streaming), thus has lower data rate (250 kbps max) but also much lower power consumption (few tens of mW transmitting and receiving). For sure you can make star networks, but also more complex tree and mesh networks. In fact, meshing is one of the main selling ...


4

Sound waves (or ultrasound) should be able to get through the can. Use a speaker and microphone (or ultrasonic transducers).


4

I would choose a RS-485 bus working with Manchester Encoding data. RS-485 because: Is cheap Is easy to implement Is uses lo power Allows for long distances (up to 1200 meters) High data rates (up to 10 Mbps) High immunity to interferences There are transceivers that allows up to 256 devices on the same bus Low part count Manchester encoding because: Is ...


4

RS-485 using multiple wires could work well here, if there's a possibility to wire the same line to all devices. If for example it's used with traditional category 5e network cable, you could have two pairs to work for data transmission in both directions (using a full duplex module), have one pair or maybe even single wire as the common ground and the rest ...


4

I know this is an old post, but since I stumbled on to it looking for a profile I had not seen before I figure this answer may help someone else. I've been working on this for a while - I don't consider my code "publishable" yet - I'm still using it in hack-and-sniff mode to find the clusters in question, but I can say the Light Link Application Profile is ...


4

All the clues are in the answer linked to in your question. Here's a recap: - Using minimum data rate (20kbps) you need a theoretical power at the receiver of -111dBm Free space link loss at 10km is 120dB (use the formula - I've used 10km and 2.45GHz) If output power from transmitter is +10 dBm, receiver power is -110dBm That's almost a perfect match and ...


4

The board is laid out with footprints for the components indicated, but they are not populated by default. Sometimes the acronym DNP (Do Not Populate) is used. Some variant of the board can be made with some or all of the indicated parts populated and possibly some other parts not populated. It allows various options of a board to be made with a single PCB ...


4

There is FW available for free. You should download TI's zstack-home from here: http://www.ti.com/tool/z-stack you the have a few options: Use IAR (this will meaning buying a license) to write a ZigBee application on the CC2530. Example Applications for the following are supplied in zstack-home SDK: Light: A light that can be turned on/off locally or ...


4

The CC2650ST supports ZigBee, BLE or 6LowPan. It comes programmed with BLE by default, you need to download the BLE sensor tag app from app store and update the FW to the ZigBee image. This will update to a ZigBee image using BLE. The App has the CC2650 ZigBee image included in it, so you just need the latest app. The ZigBee FW image makes the sensorTag into ...


4

No you can not. The Hue network is a ZigBee Light Link network, and a ZigBee Light Link Network uses "secret" ZLL security keys. Home Automation networks use public security keys, and hence if this was a Home Automation (HA) profile network then you could do this. The Hue Lights will join a HA network, so if you can create a HA coordinator and reset the Hue ...


4

tl; dr: ZigBee isn’t a subset of WiFi (802.11). It is a different protocol family, just as Bluetooth is another different protocol family. ZigBee, BT and WiFi are not directly compatible with each other, but will co-exist in the same band. What Is ZigBee, And How Is It Different From 802.11, Really? ZigBee (802.15.4) is a family of protocols used for low- ...


3

Let me compare your preferred choice, Ethernet, with my preferred choice, CAN. Components required: Ethernet: RJ45 connector, magnetics, Phy chip (unless integrated into MCU). Also need switches and a cable from the switch to each node. Each PCB needs quite a few capacitors and terminating resistors, possibly ferrites too. Needs good PCB design. CAN: ...


3

Perhaps X10 is what you need? X10 is a standard for communicating through the power lines of your house. This way you have have your Arduino send data into one power socket, which will be read by another device attached to a light fitting.


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