Not a Rocket Surgeon

Sony Google TV remote enter key problems

2011-12-06T10:02:00.001-08:00

My Sony Google TV remote was having issues with the enter key located in the middle of the directional pad. So I under took a very radical procedure to correct the problem. Basically, I changed the batteries. Works like a charm now. :-)

It took me a while to figure this out. But then again, I am no rocket surgeon.

Details about the Wii driven robot

2010-02-06T08:35:00.000-08:00

The main parts our Wii controlled robot are:

A Pololu RP5 Tracked Chassis Gray robot chassis
An Arduino
An Adafruit Motor Shield
A pair of XBee radios (see my earlier post about getting these working)
A pair of XBee adapter boards from Adafruit
An FTDI cable from Adafruit
A Wii Remote
The Darwiin Remote package

This first version of the remote controlled robot merely reads a serial command from the XBee via the NewSoftSerial library and drives the motors via the AFMotor library. The source code can be obtained here. Hooking up with the Wii Rmote is complete hack at this point. The Darwiin Remote project allows the various buttons to send keypresses. So the D-pad (directional pad) was configured to send each of the directional command characters 'w', 'd', 'x', and 'a' and the Wii Remote's 'A' button was configured to send the stop command, 's'. Then the screen command is opened on the XBee connected serial port (using the FTDI cable).

A couple of gotchas:

The silk screening on the motor shield was confusing near the expansion pins. Click on the image to see my annotations.
I've already detailed my confusion with the series 2 XBee radios (FWIW, once I had them configured, they worked beautifully!)
I had to play around with the motor connections to get the directionality correct. This wasn't really a big deal, but in the end the motor wires are mirrored with respect to each other.
I power the control components (i.e., arduino, xbee, ping))) ) using either a 9-volt or my minty boost. The minty boost is much more efficient, with the only downside being the long usb cable.

Next steps (in no particular order):

Use the positional sensors (INS) of the Wii Remote and Nunchuck to create a tank like driving system for the robot (where the Nunchuck controls the speed of the left motor and the Wii remote controls the speed of the right motor).
Use the PING))) for aided navigation to prevent ramming into objects (I have an IR proximity sensor which I'll probably use for this as well). (I worked on a project to control the max speed of a robot in a cluttered environment before. That will probably serve as the basis for this addition.

Arduino + XBee + Wii Remote

2010-02-01T04:51:00.000-08:00

Woot! Our Wii Remote controlled robot! I'll write up the details soon.

ULN2803a is a sink!

2010-02-01T04:48:00.000-08:00

Keeping true with the title of this blog, I fought with a ULN2803a over the weekend. I was attempting to create a simple mood light with my daughter. We were able to quickly construct a mood light using a small RGB LED from SparkFun. It was fun, but didn't look like a mood light. The plan going into the project was to use a ULN2803a Darlington array to drive three 3-watt LEDs and place the resulting circuit in a frosted light globe. I fiddled with the 2803, reading and fiddling until finally I figured I was much to stupid to use this relatively simple device. I looked at circuits but it just wasn't clicking. So, I decided to shelve the 2803 and merely place a white ping-pong ball over the RGB LED. The results were actually quite nice and it makes a very cool night light.

However, I am nothing if not persistent (check my other blog to read all about my all about my adventures with persistence). So, after getting KK her coffee, I did a bit more reading and finally figured out that the source of my boneheadedness was a sink! Huh? The 2803a (and several of the related devices) are current sinks not sources! Basically, the load (LED) needs to be hooked into the high side of the load voltage with the low side (i.e., negative) hooked into the ULN2803a. Duh! What was throwing me for a loop was the fact that the high load voltage source is also hooked into the 2803. I just kept thinking that the device would output the load voltage level (in my case 9 volts). But I kept reading near zero at the outputs. Only after looking at the device schematic for the umteenth time did it dawn on me that the purpose of the common hookup was to supply the built-in protection diodes a path to dissipate reverse current spikes.

I quickly hooked this all together to make a sizable mood light. The schematic is here. And a quick video is here.

Connection XBee Series 2 (AKA ZB Pro/ZNet) to an arduino

2010-01-31T09:16:00.000-08:00

My goal was to have two xbee series 2 modules communicate to each other in a two way configuration. I found the the various instructions on the internets to be confusing and hard to follow (but then again, I am no Rocket Surgeon).

My first mistake happened before I even got out of the shoot. From what I have read, the series 1 xbees are way easier and probably better suited for this task. But that is not what I ordered. sigh.

My second mistake was only ordering one communication cable (intending to use my Arduino for the other side of the communication). The cable is way useful and easier to use and works with the X-CTU (the xbee configuration utility) without any additional monkeying around.

Nevertheless, I am nothing if not determined (yes, I am slow as a frozen turkey when it comes electronics, but I do eventually get the job done).

Here is my setup:

XBee 2mW Series 2.5 Chip Antenna (you'll need two of these)
Adafruit XBee Adapter kits (you'll probably need two of these as well)
USB to TTL-232 cable (I only had one; should have bought two!)
One Arduino (the handiest one was from an ARDX kit)

Step 1: Configure the XBees

Grab the XBee control software (X-CTU) from Digi
Plugin one of the modules using the USB to TTL-232 cable and set it up to be the Coordinator (ZNET 2.5 Coordinator AT)
When first starting, setup the xbees to send and receive from any other compatible ZNET device (running at the same frequencies, etc) by setting

Destination Address High (DH) to be zero (0), and
Destination Address Low (DL) to be FFFF.

Pick a PAN ID (it doesn't matter, just so long as you use the same id on both xbees)
Write the configuration changes to the xbee (at the point, I hooked up this xbee to my arduino running the sample soft serial program in the NewSoftSerialLibrary).
Plugin the second xbee module into the USB to TTL-232 cable and set it to be an End Device (ZNET 2.5 ROUTER/END DEVICE AT)
Set the DH and DL as above
Set the PAN ID to the same id as above
Write the configuration to the device
Now use serial terminals to send packets between the modems. (I like putty, but the built-in terminal emulators in arduino and the X-CTU programs will work as well).

Finally, the blinky lights on the xbee adapter kits can tell you about state of the xbee modules. You really want to see the green LED blink constantly. The red LED will light to indicate when data is being received (as far as I know).

And there you have it.

The resources which I found useful in this little endeavor:

-Dale

I'm no Rocket Surgeon

2009-04-06T07:32:00.000-07:00

It's out there. Time to stop pretending. The truth is that I am no Rocket Surgeon.

However, I love to hack around with embedded systems and micro controllers. I have a hard time looking at something that I use often and not thinking, "this thing X would be way cooler if it did Y!"

So given that I am not a rocket surgeon, how to proceed?

Back in the day, building embedded systems was very difficult. These days it has become painfully easy (well, almost). Far and away, my favor piece of hardware is my arduino. This thing rocks! Combined with the development environment and the Processing environment, the arduino is a great little system. Also, I'd like to throw a shout out to Make Magazine and Nuts & Volts. These two publications fill my head with "delusions of grandeur" and blinky lights.