One might think that one of the typical uses for a smart wireless switch (like Sonoff devices) is to be embedded behind a normal wall switch so it becomes a “smart” wall switch. It may seem obvious but it’s not that straight forward. There are several things that get in the middle.
Most (all?) the boards have momentary push buttons while wall switches are (normally) toggle switches
Most of the available boards in the market are SPST, even those with SPDT relays often only provide terminals for COM and NO, not NC. I only have one one-throw switch at home, all the others are one-way-two-throw and are being used as part of a multi-way switch.
First problem can be easily solved in code. Instead of detecting one edge of the button signal (usually the rising edge since most push buttons are configured with pull-ups) you can detect both edges.
Last December Itead Studio updated their Home Automation product line with a new and different product. The main difference is that it doesn’t have a relay and it’s mainly sensors and no actuator (if we don’t define a notifying LED as an actuator). The Sonoff SC is a sensor station that packs a DHT11 temperature and humidity sensor, a GM55 LDR, an electret microphone with an amplifier circuit and a Sharp GP2Y1010AU0F [Aliexpress] dust sensor in a fancy case that looks like it was originally meant for a speaker.
The device is packs an ESP8266 as expected and is compatible with the eWeLink app. But, such a collection of sensors, with 3 of them having analog interfaces, cannot be run from the single-ADC ESP8266 so Itead has thrown in a good old ATMega328P to drive the sensors and report the Espressif with the data.
My daughters love to talk to (or with) my Amazon Dot [Amazon US] in their funny English: “Alexa, hello!”, “Alexa, li-on!” (actually “light on”). It’s so easy to use it to switch on/off things at home using the fauxmo python script by Maker Musings. In his post about Amazon Echo and Home Automation more than a year ago he explains how he reverse-engineered the protocol of the WeMo switches that Alexa (Amazon Echo [Amazon US] or Amazon Dot [Amazon US]) supports.
I also have a server running the fauxmo script with an MQTT handler to control some of the Sonoffs I have at home, but this morning I woke up thinking: why should I use an external script to control my devices if I can code it in the firmware?
A few weeks ago the 4D Systems announced one of its latest products: the 4Duino-24, an Arduino compatible display module with built in 240×320 resolution TFT LCD Display with Resistive Touch and an ESP8266 ESP-06 module on board.
it looked like a great product for a home automation control panel, although the screen could have been bigger. Anyway I contacted the people at 4D Systems and they were kind enough to send me a sample to review, and hack!