Friday, June 06, 2014

LED lighting control boards

Woot! I just ordered a set of PCBs for lighting control in the new house. Wifey would kill me if we had no lights, so the priority kinda jumped on this one ... (*Wifey comments:  I wouldn't kill you.  However, I consider it prudent to go to Home Depot and buy some cheapo mechanical switches just in case)

One of the more unique things about my (upcoming) house is that the bulk of our lighting are LED 24 VDC cans/pots/recessed lamps(*). Ceilings fans, chandeliers, and watercloset light/fans are standard high-voltage AC, but the bulk of our electrical fixtures are using these nifty low-voltage lamps. One neat thing is that the lamps don't require AC/DC stepdown transformers, so their cost is dropped, their reliability increases, and their heatprint is lowered.

The wiring becomes both simpler, and more complex in ways, and possibly cheaper depending on your choices. Simpler because you can run standard 14 gauge stranded speaker wire (cheap; flexible around those corners) instead of the heavier gauge Romex stuff. The lower gauge wire can save you quite a bit on copper costs, and you can lose the heavy insulation and concerns of high-voltage wires in your walls. But much more complicated because you need special hardware to run them ... a repair is no longer just a run to your local Home Depot.

In my case, much of the wiring in the house has been "home-run" back to my server room, so I ended up doubling my copper/install costs. All the control is localized to that room, which also means I don't have actual "switches" in my house, but just sensors (see Capacitive Touch Wall Switches). This leads to "how do I control these lighting circuits?"

Thus, my custom PWM Control Boards. They have an embedded microcontroller which can "do anything" with the nine (9) output channels. A higher-level "upstream" controller will tell it what actions to perform, when, and how, communicating via TTL Serial or I2C or what-have-you. The boards sink current, at whatever voltage (so I will also use these for my 12VDC LED light strips).

I've sent the PCBs off to ITEAD for production. Between now and when they arrive, I'll finish the microcontroller work that I've been working on. Assemble some parts from Mouser, plug it all together, and LIGHTS!


Will report back, as I make progress...

(*) I decided not to name/link the manufacturer until I get experience and form an opinion. Just email me to ask, if you're interested.

Monday, September 09, 2013

Capacitive Sensing Wall Switches

For my new house, I wanted to go with an unobtrusive, "no controls" style. There are no thermostats, no pool controller, no security panels, and no standard toggle/paddle switches for the lights. Instead, I'm going for a designer style piece of colored glass with capacitive touch sensors behind it. Think of your smart phone's touch capability, and that will be my light switches.

The "switches" are really just sensors, as the signals are delivered to the main house controller where the actual lighting management occurs. The sensor pad can detect touches, gestures, and multi-taps to provide different lighting requests, based on time of day and ambient light. The switches also include optional hookups to an IR/motion sensor, temperature measurement, and all switches have RGB backlighting.

All my work will be Open Source, so I've started the documentation for the wall switches. I have a couple custom PCBs that I'm working on, and (eventually) a whole mess of microcontroller code for the PIC16F688.

I'll keep updating the wiki pages, and committing changes to my repository. I don't have commit emails going anywhere, but Google Code supports feeds for wiki and source changes if you'd like to track the changes. Of course, I'll keep posting here when interesting milestones occur!

Monday, August 12, 2013

Bluetooth Household

For my home automation project, I chose to go with a fully-wired approach since I'm building from scratch. I get to run wires wherever needed, providing (hopefully) more reliability and an ability to troubleshoot problems. Certainly, the parts cost will be much lower than an RF solution.

But with that said, I met Eric Migicovsky a couple weeks ago (Founder/CEO of Pebble). He came up with a great idea: use a Pebble watch as a control mechanism. Sure, I'll have phones, tablets, infrared remotes, and various sensors... but something on my wrist? Always handy? Very cool idea! With multiple Bluetooth base stations, I can even detect signal strength and triangulate a user's position in the house, in order to provide context-sensitive menus and button controls. If you're in the home theater, then "Pause" is going to be a handy watch button, when that drink needs a refill! Given that I'm writing the app, I can even provide Wifey with her own customized watch experience.

To that end, I started doing some research on Bluetooth, and on the Pebble SDK. The first thing to pop up was the need to use Bluetooth Low Energy (aka Bluetooth 4.0, BLE, or Bluetooth Smart [Ready]) rather than the older Bluetooth 2.x or 3.x protocols. BLE allows for interactions without pairing, which is important for roaming about the house, with multiple base stations. The Pebble hardware supports BLE, but it seems that the SDK doesn't (yet) allow for applications to deliver messages to one/more/available base stations. My hope is to work with the Pebble guys to see where/how to make that available to (my) home automation application.

The second part of the problem is the development of the base stations for my house. There are inexpensive Bluetooth/USB dongles (about US$11) that can speak BLE. I've got a few Raspberry Pi boards around the house, with previously-unused USB ports. A little searching seems to indicate the dongles are supported under Linux.

These dongles seem to present themselves as an HID device (eg. keyboard, mouse, etc), and can be switched to a [Bluetooth] Host Controller Interface (HCI). I haven't dug in deeply on this stuff yet, but I do have a Fitbit dongle on my Mac OS. The Fitbit (Flex) speaks BLE, so it seemed appropriate to experiment with.

Working with HID seemed harsh, until I found hidapi. The API is very clean and simple. As a Python programmer, bindings were the next step. Ran across Cython-HIDAPI, which sucks: forked copy of HIDAPI and heavyweight Cython-based bindings (given the ugly, I'm not gonna provide link-love).

Answer: I wrote a ctypes-based binding for hidapi. My first, undocumented draft landed at just 143 lines of Python. Of course, I've checked it in, along with a sample script.

And after all that, my Fitbit dongle is purely a USB device (calling hid_open() fails). Sigh.

I've got more research to do, and maybe ordering a dongle for experimentation (see Adafruit, or various on Amazon). Maybe I can interact with the Fitbit dongle through USB rather than HID. Who knows. But once I figure the base station thing out, I can track Pebble watches, Fitbits, and other Bluetooth devices throughout my house.

Tuesday, April 16, 2013

Building omxplayer on a Raspberry Pi

The past couple days, I set aside my PIC work and concentrated on setting up a Raspberry Pi ("RPi"). I've got a couple of these, and will use them as video streamers for televisions in my house.

There is quite a bit of documentation for getting an RPi set up, so I won't repeat that here. My current focus is on getting video streaming working. An obvious candidate is RaspBMC, but I was looking for something very bare-bones to simply put a video onto the HDMI output. I ran across PyPlex which seemed right up my alley: Python and effectively an interface-less control of the video.

Yah. Well. Then I look at the setup/build requirements. twisted-web? pexpect? Seriously? Somebody has made this much more complicated than it should be. Whatever happened to just using BaseHTTPServer and the subprocess module?

Digging in, I find it is using omxplayer underneath. No wonder they're using pexpect -- there is a tty/keyboard interface to omxplayer. (of course, pty might be simpler than pexpect, but whatever) So this PyPlex thing starts up a web service and then controls omxplayer via a tty connection. I'm not seeing reliability and responsiveness here. And a lot of code, to boot.

Tearing off another layer of the onion, I start looking at omxplayer. Sigh. Requirements hell yet again. GCC 4.7. Boost. ffmpeg. Oh, and it is generally set up for cross-compilation rather than building on the RPi. This isn't a bad concept in general, as the RPi is no speed demon. But the build only takes a long time because they chose ffmpeg, whereas the Raspbian distribution uses libav. (these two libraries are reasonably similar, as libav forked from ffmpeg rather nastily a couple years ago)

So I'm looking at this giant pile of C++ code with a bunch of crazy requirements, which would take hours to build on my RPi. This is the wonderful state of video on the RPi. Sigh.

Well... I found a post by Keith Wright where he talks about building (a tweaked fork) of omxplayer on Raspbian. Much better, but the instructions still have crazy oddities about reconfiguring RAM, sudo to build in strange filesystem locations, and hey! fun! building ffmpeg from scratch again. Sigh. A guy just can't get any love around here.

Being the good geek that I am... this just wasn't something that I want to put up with. I want to build this sucker on my RPi, using standard tooling and libraries that come on Raspbian.

First up, I started from huceke/omxplayer rather than Keith's because it is much newer. But I did grab the Makefile.include from Keith, as it was sane for building on the RPi. Adjusted some of the paths to point to the installed items. Then, I had to install the following packages on the RPi: libpcre3-dev, libavcodec-dev, libavdevice-dev, libavfilter-dev, libavformat-dev, libboost-dev. As I started working through getting omxplayer built, I ran into a bug in a system header.

In /opt/vc/include/interface/vmcs_host/vcgencmd.h, line 33 needs to be changed to:
#include "interface/vmcs_host/linux/vchost_config.h"
I've filed a pull request to github:raspberrypi/firmware to fix this. Not sure if that is the Right place (that code may come from upstream?), but hopefully somebody will see it.

Next up, I had to hack away, tweak, and otherwise put a bit of pain on the omxplayer sources. Some hacks were easy, but others likely broke stuff (I'm not sure if subtitles work any more). Hard to tell. A/V code is not easy, and not something that I'm familiar with.

You can find all of my changes in my omxplayer fork. Clone that to your RPi, install the necessary packages, and hit "make". No system reconfiguration. No sudo. No hours of ffmpeg building. No GCC 4.7 requirement.

Clone. Make.

Go have fun, and watch some movies!

(my next step is to tear off the user interface bits, and shift to a simpler, pure-C library which I can wrap/control from Python)

Sunday, April 14, 2013

PIC Programming on Mac OS X

Lately, I've begun working on home automation to wire up my entire house with all kinds of goodies. The hobbyist in me, and with an attempt to be frugal, I'm skipping off-the-shelf solutions and building my own. A friend of mine calls me crazy, that it will reduce the value of my house, etc. Whatever. This is some fun stuff!

A big part of these systems is wiring together sensors and activators. You need something to control all of these things. There are a gazillion various solutions, with the obvious ones being an Arduino or Raspberry Pi and their GPIO pins (among many other features they have). I decided on a layered approach with "small brains" connected to the sensor, managing the specifics, then communicating upstream to a larger brain. I'll likely talk about the upstream bits in a later post, but this one is dedicated to the small brain: the PIC 16F688 microcontroller.

I grew up on a 6502 microprocessor. Graduated to a 68000 when it arrived in the Mac 128k. And after that, never really worried about machine/assembly code. As I looked around for microcontrollers, I ran into the 16F688 on SparkFun. This is a crazy chip -- the number of features packed into a tiny 14-pin DIP is simply incredible compared to where I came from. A couple key features that pointed me at this chip: UART on board, and about $2 per part. This allows me to do stuff such as communicate to serial sensors (such as the Zilog ePIR IR sensor), use bit-banging to communicate to I2C sensors (such as the MPR121 capacitive touch sensor), measure voltages for security systems and temperature (TMP36), ... and all in a tiny and cheap package.

Next up is programming the dang thing. I've got a programmer and my Macbook. This post will document the steps needed to get some code running on the PIC. (to help others, and if I have to retrace these steps in the future)

First, you will need the following software packages installed:

  • pk2cmd (download from Microchip)
    This uses a standard configure; make; make install
  • gputils (see their SourceForge project)
    I used "make mac105", then symlink'd "pk2cmd" and "PK2DeviceFile.dat" into my PATH
    Note: I did not setuid-root on the binary (as the docs seem to suggest). It seems to operate fine with my login id.
When I plug my programmer into the USB port and run "pk2cmd -P" it detects my PIC16F688. Woot!

And for a basic "Hello World" to test my setup, I wrote a "blink an LED" program. Download that and type "make install" and it should assemble and load the program onto the PIC sitting in your programmer. Yank out the PIC, wire up RA0 to an LED tied to Vdd (I used a 680Ω resistor), and apply power. The LED should blink at you.

Not that hard!

If it doesn't? Well. Not like you can bring up Visual Studio and debug this thing. The program works for me, and the wiring is dead simple, so I wouldn't know where to point you.

Next up: switch my blinky program to use the chip's Sleep Mode and interrupts [rather than a busy loop]. Less power consumption!

Wednesday, March 07, 2012

Oroppas, by St Clement

So it was finally time to open and drink my flight of St Clement's Oroppas wine (info on 2007 bottling). It's been waiting too long, so the wife and I decided to cook a wonderful dinner and start popping open bottles.

Flight of Oroppas, 1995 through 2002
My oldest bottle was from 1995. Waiting 17 years is certainly too long, but what's done is done. The 1995 still had a lot of flavor, rich notes, but with a very short finish (as expected).

Sunday night, we opened up the first four bottles (1995, 1996, 1997, and 1998). Since these bottles were old, I figured they wouldn't be strong representatives of Oroppas. So... I also opened up a 2007 Oroppas; the tasting notes said it was just getting ready to drink. The 2007 was our "control" bottle to really show the bold, smooth flavors of St Clement's Oroppas series.

As I mentioned, the 1995 was still good, but with a short finish. The 1996 was tasty, starting to show some of Oroppas' deeper flavor.

Strangely enough, the 1997 was a step backwards. The wine was a bit sharp and acidic, unlike the big bold flavor of the 2007. Even the 1996 demonstrated some of that boldness. Given the usual success of Napa wines from 1997, I was quite surprised. Thankfully, moving onwards to the 1998 put everything back on track. The 1998 was a good representatve of that Oroppas flavor and style. Bold and smooth, with lots of rich flavor and a great mouth feel. The 2007 had even more flavor, but still contained some of the rough tannins of a young wine; the 1998 had none of that roughness and much (though not all) of the flavor. I will probably wait at least two or three years before opening more of the 2007, to age away some of the tannins.

By mid-evening on Monday, we had finished off the 1995, 1996, and 1997. We kept around some of the 1998 and the 2007 for comparison, as I popped open the 1999 and 2000. The progression from 1998 was quite obvious with the 1999 wine -- the flavor and finish just got bigger. But the 2000 was missing the strong berry and fruit undertones, leaving just a woody finish. The 1999 was the clear winner in these few years.

Tuesday night, we opened the last two... the 2001 and 2002. This pair was very similar to Monday night's bottles: one smooth and full-bodied, and the other was a bit less. The 2001 was excellent. It had all the favor, smoothness, fruit and berry, and richness expected. The 2002 was a bit weaker on the fruit and the tannins were starting to creep in.

Okay... Wednesday evening, we opened a 2004 Oroppas as the final bottle in this tasting. It was hiding behind the flight, in the picture above (along with the 2007). Based on tasting all of these wines, I have to say: the 2004 is the absolute best of the entire pack. It has all of the fruit, boldness, smooth flavor, and only a little tannin. I would suggest that holding Oroppas for right around eight years (from the vintage date) is its ideal. (well... based on my tastes)

Overall, please remember that I'm talking comparisons here. All of these bottles were very tasty. There is just no way to call any of these bad wines. As expected, the 1995 had weaker flavor yet no tannins. Moving forward in time, the flavor definitely improved, but the true Oroppas boldness did not show up until about 1998 or so. Around 2001 or 2002, a light shade of tannins started to arrive. The 2004 seemed to be the peak in the bottles that I had.

I've been a club member of St Clement for 10 or 15 years. Their whites, reds, and specialities like the Oroppas are all fabulous wines. Their winery is a big Victorian up on a hill; it is beautiful, with a wonderful view over Napa Valley. I'm definitely a fan, and this flight has been an awesome experience. I highly recommend their wines, and a visit to their wonderful property.


Sunday, March 04, 2012

Lots of Stuff

I spent a good amount of time in front of my television. Watching shows (cable and Netflix streaming) or playing video games. The TV occupies a large portion of my life. Good? Bad? Who knows. But that isn't the topic for today...

Lately, I've been fascinated watching the show Hoarders on A&E. The show is like a train wreck -- you just can't stop watching. It is a bit sad once you truly understand that hoarding is a psychological disorder, but it is so hard to stop watching. The things that people collect, that get hoarded, the condition of the house, etc ... there is always something new on the show.

But here is where the "Stuff" from my post title comes in. There are a number of shows on that focus on "stuff". Hoarders is one show, but TLC has a similar show named Hoarding: Buried Alive. The show title is a bit crazy, given that it actually happens.

It doesn't stop there. Those two shows are about people collecting. But there are shows on the other side of the equation, too. Hoarding is about acquiring, but the stuff (sometimes) needs to go away, too. Storage Wars is about lockers that get auctioned off when people don't pay their bill. In many cases, the lockers were owned by hoarders, and all kinds of awesome stuff is found in there.

And then you have the show, American Pickers. The show is extremely fascinating. Mike and Frank find lots of stuff in peoples' hoards, but they concentrate on old items, and the history behind them. As a big History Channel fan, American Pickers is an interesting lens into history. Old cars, music legends, bicycles, cars, and other memorabilia.

The stuff that people accumulate is incredibly fascinating, and these shows provide a broad view into history, people, and an endless variety of "stuff".