Home automation

Many people desire to take control of their homes including automating simple every day tasks like for instance turning the light on and off at specific (or random) times, pulling the curtains, and monitoring the physical mail box located remotely, out of sight, at the pavement. Likewise, gaining control of  vast power consumers, i.e home appliances, is something that many folks can use to minimise their utility bills. Remember that a standby power consumption of 1 Watt translates into 1 Watt-year, if the device is never disconnected from the mains. Under Danish conditions that is equivalent to an expense of approximately EUR 2,75 on an annual basis for each Watt standing by. Lastly, monitoring and improving indoor climate has huge potential. See my e-nose project for a technical solution for this specific welfare issue.

A simple way to implement home automation is by using the principles from an industrial programmable logic controller (PLC) and the private wireless network, which you probably already have at home.

My proposal for a network topology for a home automation system comprised of several autonomous PLCs is depicted below. Observe that the Internet connection is provided through an LTE router, which gives both the LAN (wired) and the WiFi (wireless) connections to the private network. A switch is needed to increase the number of LAN lines and a Power-over-Ethernet (PoE) mid-span injector is added to reduce the cabling to each individual PLC (hereinafter refered to as nodes). Next to each node a PoE splitter is added to split the LAN signal and power lines.

0x05_network_topology

For nodes I have developed my own design based on the Arduino Nano and the ENC28J60 Ethernet controller. See the 0x05 design page for more details. The mid-span injector is a primitive device sourced from eBay; so are the PoE splitters. The Ethernet switch is a generic 5 channel device, where 1 channel is connected to the LAN port on the LTE router, which is a Huawei E5180.

For development purposes a desktop unit of the 0x05 could be fitted as shown in the below figure. Mechanical switches determine, whether digital pins are normal input/output or buffered. All eight analogue pins (A0 through A7) and eight digital (D2 through D9) are broken out to cinch/phono connectors. LEDs show the states of the eight digital pins (D2 through D9). The four relays each connect to a Schuko outlet with individual fuses.

case_desktop

 

Updates on the implementation will follow during 2017.

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