Saturday, April 12, 2014

Engine Monitor Progress

I am gaining a bit of experience in Android development. Some things I did in that last app are helping, while I need to learn more to make this work. One thing I have clearly learned, the drawing canvas can be made into tiles. This is important, since if the app is to display both in portrait and landscape, it will be much easier to move individual gauges around than trying to use different offsets depending on orientation.

rough example

The other thing I learned, these gauges can have a million options! I may need about half that many before I am done as well. Should the round gauge turn clock wise or counter clock wise? Should the green arc be thick or thin, should the ticks be shown or not. Of course I can add all those options, and I still need to add more.

I've built the individual instruments using normal Object Oriented (OO) concepts. I could just as easily substituted the tachometer as a bar graph as a round gauge. I also have the ability to build an new type that can be a line graph or something, and only have to change the code a little. I can change the individual gauges, and probably not have to change the implementers code as well.

The OO concept allows a great deal of flexibility. Everything is abstracted away, such that the value of the fuel pressure will not really care what color the pointer is, or that the gauge is round or some other shape. Where it is placed on the screen is equally irrelevant, and allows the user to change the layout of the screen to suit their needs, and present the most important information in the most prominent position.

I am making progress, I just keep getting bogged down in implementation details, that can probably wait. Some of you are looking at this and saying, "it isn't very good". Fine, tell me what other things I should change to make it better looking. I've already considered OpenGL 3D looking instruments, and non-linear scales, red lines at limits, and many other things. The app will include audio and visual alerts depending on settings.

For now, I have all the instruments I need for my airplane on the screen. I have provisions in the code for 6 and 8 cylinder EGT/CHT values, as well as manifold pressure, and temperature. I want the screen layout to be customizable by the user, so they can pick the instruments they want, and where they are on the display.  

 Thanks for your feedback so far.

Sunday, April 6, 2014

After You Rewire it...

Yesterday I stopped by an estate sale. They had a Robosapian V2 for $10. This is a robot I've wanted for years, but they cost more than I could justify. I thought $10, why not. The remote seemed to work, and it had batteries in it, I thought for $10, I would take a chance on it.

It needs 6D cells and 4AAA batteries, so I stopped off and picked up some batteries for another $15. So now I am $25 into it, and it doesn't seem to work. My normal mode after buying something like this, and finding it doesn't work, is I Google for similiar failure modes. This failure mode is, it does nothing. I opened up the feet again to be sure I put the batteries in the right way, which I have, but the one pair of AAA batteries are super hot, like I can't hold them.

Reading some of the fixes suggested, was a youtube video about how easy it is to rewire this thing. I watched about half of it, and thought, this is like Tim Taylor rewiring everything just because. Another site suggested rewiring the legs. The one site suggested it is easy to open the robot up, so I thought, I can open up the torso to measure voltages on the main board.

Insulation has flaked off and is covering bits of the robot insides. 

What greeted me when I opened it up was shocking! Insulation just flaking off of the wires. Most of the wires that went to the legs had about 50% of the insulation missing. I continued opening up the robot, and when I got to the legs, there were parts where all I saw was a mass of copper, you could no longer tell one wire from another.

I thought I would try the rewiring repair. I went to Radio Shack to see what they had for wire. There was a significant gap between the 22GA wire and the 30GA wirewrap wire that they didn't have. I bought the 22GA wire to use for the motor power, and decided to cannibalize a Cat 5 cable for the logic wiring. It took about 4 hours to do all the wiring. There are several sites with details on what the wires are for.

I want to blame some MBA or manager for making a really bad choice here. I don't know for sure, but someone at the company decided to cut some corners with the quality of the wire. Some of the wire in the robot is fine, but the critical wires (the ones going from the body where the computer is, to the feet where the batteries are, and they move a lot) are just crap.

I was short of resources as well. The connectors that are in the robot are pretty cheap as well, but are a common connector. They have tin crimp on pins. Rather than risk the whole pin, or the body of the connector, I decided to strip back about an 1/8" of wire and solder my new wire on with some heat shrink to insulate the connection.

Once I got the wiring done, it still didn't work. I tried using a meter to trace the trouble. I was not getting any voltage from the AAA batteries in the one foot. When I opened that up, I found the connector in the cover was covered with corrosion, and not making good contact. After cleaning up the connection here, the robot started jiggling around and talking!

Success! I now had a working Robosapian V2. I started putting the panels back on, and covering the robot up, so it looked like it did when I brought it home. I messed up on some of the screw placement, but it went together, and looked good.

I played with the sensors for a little while last night. The blob detector is pretty good, and worked really well. The motion detector was pretty good at well, I could get it to flail backwards and scream when I swatted my hand towards the head. It walked and reached with the remote. So I went to bed.

When I got up this morning, I started messing with it more. I wasn't using the manual, just randomly pushing buttons. I clicked on the "D" button that starts the dance routine. It was playing music and moving quite a lot, then it quit. It seemed to quit on a proper down beat, but was in an odd position to end a dance.

3 of 6 wires are broken from white connector

Nothing worked again. Grrr! how much do I need to open up to find the trouble this time?  I opened the torso, and the trouble was obvious. My soldering on to the connector ends made the wire brittle. People have told me before, "don't solder your crimp connectors, it makes the wire brittle", but in this case, I didn't have much choice. Most of the wire was already missing the insulation, and I didn't think making long pigtails with lots of heat shrink was a good idea. (I didn't think of long heat shrink coated wires at all).

I've ordered some new connectors. I will replace all 4 of the connectors I soldered to like that, and make sure there is enough jiggle room between the connector and the solder joint.

After you rewire it, you do some pretty cool things with this robot!

These robots are a challenge.

Friday, April 4, 2014

App In the Playstore

Like I said in the last post, my app is in the Google PlayStore, and can be downloaded by anyone. There were some things I found out the hard way, but overall, it was a pleasant experience. Yes, I am working on the engine monitor, I just needed to get this wrapped up. I am guessing there will be updates when people start giving me feedback, and there are a couple items I want to update for the next revision.

To get an app in the store, you need to sign up as a developer.  This is a simple task, agreeing to Google's terms, and paying $25. The $25 is a one time fee, and allows you to put in as many apps as you want.

The Playstore is trying to be fair to everyone, without putting them at risk. They don't want apps that are all spam, or extortion type apps, where you can't use the app without paying something extra. They kind of control that by mostly forcing you to use their services to pay for the in app purchases, if there are any, or to clearly label your app as pay to use.

If you want to distribute your app outside the US, you need to certify that the app doesn't break any ITAR rules. They ask you to check a box, and aren't really into looking for specific certifications. That check box probably keeps Google an arms reach out of any ITAR enforcement action.

The one thing that took the most time, Google was a little more picky about my package name. This, being my first app, I went with the defaults in Android Developer Studio. When I created the app, it asked for the package name, and filled the box in with "com.example". I didn't make any plans at the time, so I left that alone.  When I uploaded the app to the playstore the first time it rejected it, saying that "com.example is reserved for special items".

You can look, according to, is available to be used for illistrative purposes:

As described in RFC 2606, a number of domains such as and for documentation purposes. These domains may be used as illustrative examples in documents without prior coordination with us. They are not available for registration or transfer.

Wow, who knew. For the engine monitor code, I changed that already to com.engmon, at least for now.

All the icons I had already done. If you look at the icons on a phone, they are a little better looking than in the play store. Maybe if I was making money from this app, I would hire a graphic designer to come up with something clever, but these kind of illustrate the walking outside the app requires.

I did need a large icon to get it in the play store. I didn't start with the big one(512x512 pixels) while building the app. I started with the second big one (144x144pixels), and built proper layers using gimp to build the icon. I scaled the 144 pixel image down to make the smaller icons, and that worked well, as I expected. I tried a couple trees in front of the Android, but it didn't look well. For the big image, gimp did an OK job scaling up the 144 pixel image.

The other thing the app needed, was to be built without any debugging turned on. I get it, many of the debugging facilities are entered using various networking ports. Once someone has access to an app, in a nefarious way, they can do bad stuff, due to the fact that there is really only one user for all the apps on the smart phones out there. All apps have the same permissions for everything.

Google has some funny algorithm that determines where the app shows up when you search. When I type in Acreage calculator, it find an app called Acreage Calculator (the play store allows apps to have the same name, I am guessing trademark registration would trump any conflicts, but I am not gonna worry about it). The other app converts square meters entered in a text field to acres, as a converter would do. My app didn't show up this morning. It may when it gets enough downloads, but how do you get downloads if it isn't visible?

You should down load my app and give it a shot. Please give me feedback in the Playstore, or here. Your ideas may be incorporated in the next release of the app.

Thanks for listening.