Das Blinken Bonken!

Seems like end of the year is DYI electronics projects time for me as the Sound Alarm happened round this time last year too.  Well, I’ve been having a ball making Arduino stuff, this time as Christmas presents.  This time I got my documentation act together even more and made a construction tutorial on instructables too!   The code for Das Blinken Bonken is on github, and here’s a video of Jesse showing off the game:

Arduino Sound Alarm

I’ve just completed my second Arduino project, a sound level detector which sets off an “alarm” when there’s the sound level is to high for too long.  I built it for use in a school that wants to provide visual feedback to students when they are being too loud.  The “alarm” is a string of flashing LEDs that’s controlled by an IR-remote, which I reverse engineered using the the arduino itself and the excellent IRremote library to figure out which codes activate the LED string. The IRremote library includes an example that dumps the codes and code types that remotes typically use.  So I just ran that example with my arduino hooked up to an IR detector from adafruit.  It was really quite easy to do.

It’s been a fun project because it’s quite flexible and configurable.  Here’s a short video of the finished product:

For anyone who wants to build one of these here’s a bread-board diagram that I made using the very cool Fritzing package:

The Adruino sketch that powers this is available on github.

Here are some details on the circuitry.  The sound detector is based on the ZX-Sound board. Here’s a nice post on the arduino.cc site that I used as my starting place for building the sound part of this board.  The video helpfully includes a parts list which I sourced from Allied electronics, all except for the mic.  The LCD is the $10 16×2 from Adafruit (their tutorial on wiring it up was great), and I also used their electret microphone.  One note about the microphone is that it’s polarity matters.  If you get it in backwards, it’s much less sensitive.  I found this out purely by accident!  I also used their IR LED.

Here are some photos of assembling the project.

First the prototyping phase:

Then building the connector for the LCD:

Then drilling holes and installing the configuration controls (push-button and pot)

Then assembling and soldering the board with the sound circuit and the trim pot for the LCD as well as the resistor for the IR LED.

Finally, just before enclosing..

The completed project.  Note that I left the mic and IR LED lose because I’m not sure exactly where the alarm is going to be installed and the way they face could matter.

Some lessons learned:

  1. When soldering a header for an LCD remember to take into account that if you copy the wiring order as you have plugged it into the bread-board, you will actually be doing it backwards because the connecter will be attached upside-down!
  2. You will need to drill a little extra hole in your case to accept the tab on the pot that keeps it from rotating when you spin the shaft.
  3. Electret microphones have a polarity.
  4. Hot-glue is great for attaching push-buttons.
  5. Ask you children for UI advice!  Will had the excellent idea of using the setup-pot to spin between the different settings.  In the original code I had it so you had to press the button to toggle between the setup parameters and then do a long-press to actually set one.  The way it ended up is much better.

Parts List:

Arduino Uno: https://www.adafruit.com/products/50 ($29.95)

Makershed Arduino Enclosure:  http://www.makershed.com/Clear_Enclosure_for_Arduino_p/mkad40.htm ($15.00)

9V powersupply: https://www.adafruit.com/products/63 ($6.95)

100K Potentiometer: Radioshack ($1.69)

pushbutton switch: Radioshack ($.99)

Breadboard PCB: https://www.adafruit.com/products/589 ($3.00)

Electret Mic: https://www.adafruit.com/products/1064 ($1.50)

IR LED: https://www.adafruit.com/products/387 ($.75)

LCD 2×16: https://www.adafruit.com/products/181 ($9.95)

Components: (~$5)

  • resistors: 1k ohm x 2; 100k ohm x 2; 12 ohm; 39k ohm; 22k ohm; 230 ohm (for IR led)
  • capacitors: 470uf 16v; 0.1uf 50v; 22uf 25v
  • Dual op amp IC: TLC272

Total Price: ~$70

Upgrading postgres on Snow Leopard (Mac OS X 10.6)

Well, I too have gone down the rabbit hole of having to upgrade compiled-from-source apps to 64bit architecture after moving to Snow Leopard.  The hardest by far was postgres.  The sad thing is that 32bit version works just fine, but the adapter gems for rails don’t, hence the need for the recompile.

Mostly I followed this blog post, but it assumes that you had previously installed postgres using his instructions for Leopard which I hadn’t.

My previous installation was at /usr/local/postgres and these instructions end up installing it at /usr/local/pgsql, so my task also includes getting the data from my previous installation to the new on.

I also took some some hints from this post.

Here’s the blow by blow:

Make a backup of all my data from the 32bit version:

pg_dumpall > /tmp/32-bit-dump.sql

Switch to super user, make a directory for the source (if you haven’t already), download and extract it:

sudo su
mkdir /usr/local/src
cd /usr/local/src
curl -O http://ftp9.us.postgresql.org/pub/mirrors/postgresql/source/v8.3.8/postgresql-8.3.8.tar.gz
tar -zvxf postgresql-8.3.8.tar.gz
rm postgresql-8.3.8.tar.gz

Now configure, make and install it:

cd postgresql-8.3.8
./configure --enable-thread-safety --with-bonjour
make install

Then I followed the instructions from the above mentioned blog on how to make a postgres user, but I did them in a different terminal window because remember the other one we were logged in as root:

“First, you’ll need to find an unused user and group ID. Use the following commands to list the IDs for the users and groups on your system.”

dscl . -list /Groups PrimaryGroupID | awk '{print $2}' | sort -n
dscl . -list /Users UniqueID | awk '{print $2}' | sort -n

“For the purposes of this tutorial, let’s assume an ID of 113 for both the user and the group. Since the convention is to prefix system accounts with an underscore, use the following commands to create a user called _postgres:”

sudo dscl . create /Users/_postgres UniqueID 113
sudo dscl . create /Users/_postgres PrimaryGroupID 113
sudo dscl . create /Users/_postgres NFSHomeDirectory /usr/local/pgsql/
sudo dscl . create /Users/_postgres RealName "PostgreSQL Server"
sudo dscl . create /Users/_postgres Password "*"
sudo dscl . append /Users/_postgres RecordName postgres

“Then, create the _postgres group:”

sudo dscl . create /Groups/_postgres
sudo dscl . create /Groups/_postgres PrimaryGroupID 113
sudo dscl . append /Groups/_postgres RecordName postgres
sudo dscl . create /Groups/_postgres RealName "PostgreSQL Users"

So at this point the binaries are installed and there’s a user to run it under, but I needed to initialize a new database and copy back in my saved data. First create the data and log directories and set perms:

sudo mkdir /usr/local/pgsql/data
sudo chown postgres:postgres /usr/local/pgsql/data
sudo mkdir /usr/local/pgsql/log
sudo chown postgres:postgres /usr/local/pgsql/log

Then I logged in as the _postgres user:

sudo su
su - _postgres

And initialize database files and start up the database:

/usr/local/pgsql/bin/initdb -E UTF8 -D /usr/local/pgsql/data/
/usr/local/pgsql/bin/pg_ctl -D /usr/local/pgsql/data/ -l /usr/local/pgsql/log/postgresql.log start

Finally I restored the data from my initial pg_dumpall

/usr/local/pgsql/bin/psql -U postgres  -f /tmp/32-bit-dump.sql

I’ve also added these lines into my .profile to add the commands to my path and to simplify starting and stopping the database:

export PATH=$PATH:/usr/local/pgsql/bin
export MANPATH=$MANPATH:/usr/local/pgsql/man
alias pg_stop='sudo -u postgres pg_ctl -D /usr/local/pgsql/data stop'
alias pg_start='sudo -u postgres pg_ctl -D /usr/local/pgsql/data -l /usr/local/pgsql/log/posgtres.log start'

And then finally I could install the postgres rails gem (which was the whole point of this silly excercise):

sudo env ARCHFLAGS="-arch x86_64" gem install pg


I was looking at how perl6 is coming along and found this: http://perlgeek.de/blog-en/perl-5-to-6/ which is really cool.  Besides being a really nice presentation of the material (including the “Motivation” section) there’s just lotsa nice stuff.  Some of the new way outa here cool perl6 features:

  • meta operators
  • gather/take construct for lazy lists
  • grammars
  • Enums
  • twigils
  • custom operators

And that’s just a few…

Enjoying being on the Wagn

We are building out the new currency frontiers web-site, using the Wagn, which is pretty darn cool. It’s a wiki + database + cms. It’s kinda geeky, but not so much that you have to be a programer to use it (so don’t freak if your aren’t), but if you are a programming inclined, there’s lots of nice stuff you can. Ethan and Lewis are are the excellent chaps wheeling the Wagn. Kudos dudes.