Oct 202014
 
Point Cloud Thumbnail

Point Cloud Thumbnail

This was kinda cool – the animated GIF shows the results of my first point cloud of an Eagle on the backside of a US quarter! The cloud was created by using the HAAS VF-3 at i3Detroit and an old laser sensor I’ve had for decades.  The laser sensor I used is a “LM100 Laser Analog Sensor” from NAiS with a part number of ANL175A.  The sensor is rather old – the sensor manufacture date says “June 1992″.  The sensor has an output of zero to 10 Vdc and a range of 75mm (just under 3 inches).  The results so far seem poor at best.  The problem, I’m guessing, is that I’m asking the laser sensor to measure beyond its capability.  Another problem was the laser orientation to the scan direction.  Well, at least that’s what I’m guessing today – see pictures below for more.

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Aug 262014
 
Ultrasonic Sensor Circuit

Ultrasonic Sensor Circuit

Whoops…

I goofed in my original series of posting concerning the ultrasonic IO circuit.  The circuit is used to interface automotive ultrasonic sensors.  The circuit allows transmitting and receiving signals.  I’m not sure what was going on in the original posting but the circuit I showed was terribly wrong.  It was over four years ago when I posted the original so I’m not sure what I was thinking back then.  Anyway, the image at right shows what I think is the correct circuit.  Luckily, I was able to pull out the original proto board I built from four years ago.  Cause I never throw anything away!

Just in case, below are a bunch of pictures I took of the board.  I’ve tried to take a bunch of pictures so you too can reverse engineer my old working circuit.  The pictures show both the front and backside of the board in high resolution.

Sorry if my original crappy circuit goofed anyone!  Oh, and thanks goes to Sebastian for pointing out my blunder.  Hope this new circuit diagram helps.

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 Posted by at 4:20 pm

Mar 072014
 
CC2538 Dev Kit

CC2538 Dev Kit

I’m a gonna get serious about this whole IoT!  To that end, I just bought myself a brand new CC2538 development kit from Texas Instruments.  Yeah, it was $300 bucks, which hurt, but since I’m using a bunch of modules from China I wanted some rock solid hardware to compare against.  Plus, the “SmartRF06″ board has a bunch of goodies like a graphic LCD.  For $300 bucks, the kit contains: 2x SmartRF06 boards, 2x CC2538EM radio modules, and 1x CC2531 USB dongle.

Note, the CC2538EM radio module plugs onto the SmartRF06 board.  In other words, the SmartRF06 board is a mother board for the CC2538DK radio module.  The SmartRF06 board has a graphic LCD, a couple buttons, some colored LEDs, and a light sensor.  The USB stick is still using the old CC2531 radio chip which is based on the CC2530.

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Feb 152014
 
CC2530 Radio Module

CC2530 Radio Module

I’m starting a new series of postings that will cover the TI CC2530 IEEE 802.15.4 single chip radio using Contiki OS.  Step #1, get some hardware to play with.  The picture at right shows a $10 dollar radio module which I purchased from AliExpress.  Actually, to get the $10 dollar price, the lot size was for four radios which made the sell price $40 bucks (with free shipping from China).  Each radio module includes a TI CC2530F256 radio / micro from TI where the “F256″ means the chip has 256k of flash space.  Great deal!

I also ordered a dev kit for $27 bucks (again, free shipping) from AliExpress at the same time.  The dev kit, visible in the following picture, is really a product from Waveshare Electronics.  Note, the picture shows a bunch of other stuff too.  The $27 dollar kit (also available on Amazon for $30 bucks) has one ZB500 mother board, one CC2530 daughter card radio, a little whip antenna, and some old-ball “AT45DBXX DataFlash” board which I have no idea about.  Oh, and they also include a homemade CD-Rom with a bunch of software thrown on.  The most interesting being a cracked version of the IAR compiler.  Yeah, I tried it and it worked perfectly.  However, I can’t bring myself to use a cracked piece of software like that even if it is valued at over $3,000 bucks.  Besides, if I used cracked software I wouldn’t be able to share source code with all of you!  Luckily, the Contiki OS is all setup for the CC2530 radio.  The current version, Contiki 2.7 download, includes a compiler that handles the CC2530 chip just fine.  More on that later!

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Dec 232013
 
D Cell NiMH Battery

D Cell NiMH Battery

Seems like 12V lead-acid batteries never last very long as scooter batteries!  My one year old scooter already has a set of batteries that won’t last more than 1/2 a mile.  Compared to 6 miles when the batteries were new.  Buying another set of crappy lead-acid batteries was not very appealing.

The remained of this post details my attempt to build a 36V / 10aH replacement battery pack for my scooter.  Two things to know.  One, this is an expensive option when compared to simply buying replacement lead-acid batteries.  Second, this is an experiment on my part – I make no claim I know what I’m doing here.  Your mileage may vary big time!

About cost, a 12V / 10aH battery cost $16 on Amazon.  My scooter uses three of these batteries in series to develop the 36 volts needed.  So, three replacement batteries would cost $48 bucks.  Compare that to $233 dollars for 32 D Cell NiMH batteries!  Yep, that’s around $7.25 per one D cell NiMH battery.  Each D cell is nominal at 1.2 volts at 10aH.  So, 32 cells taken together generate 38.4 volts (at 10aH).  Oh, and you need a special smart charger for the NiMH batteries too.  Can NOT simply use the standard scooter charger that came with the scooter since it was designed for lead-acid.  Here is a link to the $50 dollar charger I bought.  Bottom line, lead-acid replacements cost around $50 bucks and a complete NiMH replacement cost around $285.  Almost six times more expensive for NiMH!  Ouch.  Well, since my son plans to ride the scooter to school every day I kinda, sorta, might be able to justify the expense.  He rides two miles each way five days a week recharging each evening.  We’ll see if the NiMH batteries are more durable.

Read on for a how-to for lead-acid to NiMH conversion…

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 Posted by at 9:34 pm

Aug 142013
 
BeagleBone Black

BeagleBone Black

My first impression of the BeagleBone Black was not good!

My problem with my new BeagleBone Black (known hence as BBB) was due to the default operating software, called Angstrom, loaded on the eMMC 2GB flash.  I’m sure the Angstrom distribution has some merits – but I’m an old man who is hesitant to learn yet more stuff when not absolutely necessary.  I almost gave up on the BBB after attempting to get Python / PyGame installed and running on the Angstrom distribution.  Just on a whim, I started the process of building up a micro SD-Card with the Ubuntu distribution.  Not sure why, but it seems to be called Ubuntu Raring.  Oh, and the GUI stuff is done with LXDE (which stands for “Lightweight X11 Desktop Environment”) instead of heavyweight Gnome.

The rest of this post is just my abbreviated notes / steps on bring up the BBB with Ubuntu / LXDE.

Read on for more details…

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Aug 082013
 
RPi LCD Display

RPi LCD Display

This post is just a bunch of notes regarding my attempt to create a useful Raspberry Pi LCD display.  What is shown on the display is rather arbitrary – what I’m after is a small (inexpensive) display solution for bunches of different project ideas.  All the projects share the same problem – how can I have a cool little LCD display integrated right into my project.  Maybe the display will be a DRO (digital readout) for a CNC machine.  Maybe the display will be bolted on a little two wheel robot.  Maybe bolt the display in my vehicle for decoding real-time vehicle data.  Or, as shown here, maybe the display will sit and display real-time weather.

So, what follows is a step-by-step, mainly for myself, guide for setting up a Raspberry Pi as a real-time weather display.  To do all the GUI stuff I used Python + PyGame.  This made it really easy to make a pretty display – which is difficult on a really small composite video display.  All the fonts had to be really big to show up nice on the display.  Once per second, PyGame is used to completely redraw the display.  Then, once per minute, the code fetches the current weather conditions and forecast from Weather.Com.  The weather and forecast are based on my zip code that is part of the data request to Weather.Com.  On average, Weather.Com updates the weather / forecast four times per hour.  It all seems to work very well.  Read on for all the juicy details.

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Jul 232013
 
Garage Monitor Radio

Garage Monitor Radio

This is a multi-part posting about hardware and software development centred around the TI (Texas Instruments) SPI based CC2500 data radio module coupled to a MSP430G2553 micro.

The big news in this posting is, I’ll describe a complete open-source tool-chain solution for developing software for the CC2500 radio.  This includes my porting the TI SimpliciTI software stack over to the Gnu C compiler!  Also big news, the TI CC2500 radio module, with free shipping direct from China, costs less than $2 bucks!

As a good working demo example, I finally have a complete CC2500 data radio attached to my Garage Door that will monitor the opening and closing of the big door.  The main picture here shows the garage door monitoring radio just before hiding it away inside the false ceiling of my garage.  The module monitors a magnetic door switch for any activity.  Just for good measure, the garage monitor sends a “State-Of-Health” message once per second.  Therefore, any listening module that comes online only need wait a maximum of 60 seconds before “knowing” the state of the garage door.  No more leaving the stupid garage door up all night!

This is just a simple example application of using the TI CC2500 data radios for a really useful purpose.

Read on for all the details regarding the $2 dollar Texas Instruments CC2500 data radio module using open-source tools.

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 Posted by at 3:34 pm

Apr 202013
 
Chamberlain Thru Beam Signal

Chamberlain Thru Beam Signal

This image shows the signal between the garage door thru beam sensors and the garage door opener head unit (head unit is what I call the main part that actually opens the door).  To probe the thru beam sensors, I just added some extension wires on the terminal strip where the normal wires, coming from the sensors, are terminated.  I wanted to see what happens when something blocks the electric eyes.  Sure enough, the signal goes flat-line when something is blocking the eyes.  Only when the path is clear does the signal return to normal (as shown in the main picture on this page).

So, for a normal “not blocked” signal from the thru beam eyes, the signal looks like 6Vdc, with short 1/2 millisecond pulses spaced every 6 1/4 milliseconds.  Makes sense, I guess, the thru beam eyes steal / store power from the signal between pulses (as stored energy in a big capacitor) – then, the eyes generate short pulses to ground while using the stored energy from the storage capacitor that is within the sensor eye itself.  Well, the sensor generates those pulses if the thru beam is clear.  If the beam path is block the sensor simply stops generating pulses.  This makes it possible to operate both eyes (one on each side of the garage door near the ground – one eye generating IR light and the other eye receives) using only two wires.  Using only two wires keeps the cost down.

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 Posted by at 1:21 am
Apr 192013
 
Chamberlain Garage Door Opener

Chamberlain Garage Door Opener

This is a first posting, in a multipart series, about hacking my Chamberlain garage door opener.  In the end, I hope to have a MSP430 + CC2500 radio integrated on my garage door opener.  Handling the magnetic reed switch on the door will be easy.  Ultimately, I hope I can also tie into the motion sensor and thru beam on the Chamberlain.

Years ago, I installed a switch input X10 module (PF284) on my garage door.  The X10 module would send a message whenever the magnetic reed switch on the door changed state.  Inside the house I had a small nightlight that would come on whenever the door was open.  The system kept us from leaving the door open at night and worked great for many many years.  Then one day, the X10 module just simply failed!  Soon after, about once a month we forget to close the door and leave the darn thing open ALL night by forgetting to close it on the way to bed.  Got worst, on morning we found a note from the Police, “Bad idea leaving your door open all night.”  Like I needed them to tell me that.  So now Momma is ticked and wants a fix ASAP!

I know what your thinking – just put a timer on it.  A simple little microprocessor controlled relay.  If the door is open for more than an hour then automatically close it.  Yeah, that would probably work.  And yeah, I could add a button on the micro enclosure to have it give an extra couple of hours before it times out (for lazy Saturday’s when we’re working around the house and actually want the door to stay open).  But where’s the fun in that?  No, by golly gosh, we’re going wireless baby!

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 Posted by at 1:57 pm
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