Sunday, 27 November 2016

The ESP-Live

I was doing some shopping (read: surfing Amazon) for Black Friday and I was checking out all of the home automation gear. Things have come a long way! Home automation has been a passion of mine for many years - although to date I still haven't automated my lights! I will eventually prevail... I think that with the ESP-Live (my latest attempt) I will prevail.

Many years ago, when I was still in school, I remember interfacing some LEDs to my old Pentium I box via the parallel port. I had set up a Visual Basic 5 program to write bytes to the port. I messed around with logic chips to expand the number of input and outputs I had and I even had some transistors to switch relays. Sounds pretty primitive - right? The cool thing about this prototype system was I had a pretty good voice recognition system written using the Microsoft Speech API and it could respond to quite a few commands:

"Computer, turn LED one on.", "Computer, turn LED one off.", "Computer, start Linkin Park, Parpercut.", "Computer, set volume ten.", "Computer, pause music.", "Computer, pause music!!!". And it didn't work because it couldn't hear me over the music...

Nowadays the Google and Amazon speech recognition are getting really good. I think I will work on a project to interface the speech recognition into my home automation, one day.

Back to the point. Why do I still not have a working home automation system, you ask? I have spent many years trying to develop my own custom system. I personally think that buying a system off the shelf is too easy... and no fun! There are also features that I want, that probably don't exist except in extremely high end systems (and I haven't necessarily decided on these features just yet!). I have gone through many iterations of design with different technologies, but one fact remains: the switches must be wireless so that they are easy to install and they must fit into the wall to replace my current switches.

Perhaps some day I will write a post detailing all the light switched I have half designed... and why I stopped.

What is the ESP-Live?

Arduino has pretty much taken over the hobbyist world in my opinion. It's really easy to get something up and running in no time compared to the DIY approach with the raw microcontrollers, in circuit programmers, etc. Kind of like C++ versus C#, I guess.

I usually prefer to not use something like Arduino, because it's too easy. In recent years, however, I have changed my mind. I think that since Ardunio is literally just a comprehensive C/C++ wrapper on top of existing Atmel gcc, it's not really cheating... I still want to design my own hardware - but at least now I can do that and not waste too much time on bringing it to life.

I like the ESP modules because they have a lot of documentation and are powerful and really cheap! I like what NodeMCU has done in making the ESP8266 more like an Arduino, but I still want to do C programming and not script in Lua.

The ESP-Live is an ESP-12F module, on a fairly general purpose board with all of the IO's broken out, with a USB-Mini port for programming and debugging, power supply, etc.

What's different then? 

The ESP-Live has an on board AC/DC converter so that you can connect it directly to the mains! The shields can then be things like TRAIC or MOSFET dimmers, power measurement boards, etc. I have also designed it to be as compact as possible. The final design measures a mere 30x65cm! Small enough to fit inside a 2x4 inch light switch box inside the wall.

I'll post the design files on GitHub soon.

PCB and Schematic:

A 3D rendering of the top of the PCB. The areas for the ESP module is visible on the right. To the left is the area for the power supply module and AC input.

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