Scenic Thoughts and Custom Wants

Rattlesnake Point, Halton Conservation

2011-10-16T00:12:00.000-04:00

The start line

Visited a new trail today. Figured would cash in that Halton Conservation passport. It was an interesting drive, up on Appleby.

Very red leaf

I arrived at the park at 8AM and there was already plenty of rock climbers, starting their day. Several tents set up (people spending the night?).

The weather did not want to cooperate. It was rather cold and very windy. Rain drizzled most of the hike. I didn't bring my rain jacket, but my regular one kept most of the rain away.

Most of the property on the map, seems to be connected by narrow asphalted roads, providing great access for the climbers, but ruining the loops that could be made for hikers. But then, this property is not that large, so no great loss.

View across the canyon

Where did they get all that wood?

The park is sitting apparently on high side of the ridge of a canyon. The other ridge, on the other side of the canyon, is taken up with Crawford Lake park. The interesting trail is the one connecting the two parks, going down and up the two ridges, right through the bottom of the canyon. The map claims it to be a 7k, one way, trip, or 2-3 hours hike. Four hours and change was how long it took to go there an back.

Wow, rails. The safest part of the trail!!!

"Comfort is important" -- Mahoney, Police Academy

Despite the weather, it turned out to be a great hike. I can only imagine, how great a trail this would had been with the sunny weather. The maple leafs are just turning color. The view across the gorge is quiet spectacular and colorful. The ground is covered ankle deep in leafs. They look great, but is it ever slippery. The wet stones on the ground and the leafs on top, make sure your eyes stay firmly glued to your toes, rather then gawking at the view.

Typical to Halton Conservation parks, the trail is very rocky. But unlike the Hilton Falls, this trail is far more challenging. Well, at least if one is to follow the blue and white blazes, rather then orange markers. Did I mention slippery? Yes, tricky walking, probably not recommended for icy conditions.

"Steep Hill". Perfect for portaging

Sampling the curative properties of mud.

It is not particularly long. Just like Hilton Falls, there seems to be a map at every fork in the road, which is great at removing any lingering anxiety of taking unknown trail. Somewhere along the middle, the map boasts of a foot bridge across the canyon. Now, if you pictured one of those rickety suspended bridges that swing to the rhythm of the wind, yes, we both been fooled. This foot bridge is in a developed country. It goes whole of two feet off the ground and has rails, even benches along the way. The quantity of wood and the workmanship make it an interesting contraption in the middle of a forest.

Damn tourists and their cameras. Just go away!

Local Air Force, grounded due to weather conditions

About ten, twenty minutes, I came across the other warning the map gave: the steep rocky hill. Of course this hill has nothing on the unmarked hills we took down at Tiffany and Webster falls trail. But this one is marked. There is a side trail that claims to be an easier way up. No fun in taking that. This one is rather fun to navigate through. My first thought, going up this hill, was, "at least I am not portaging". My very next was, "heck, if I was, at least I would be dry". Yes, the rain was making the stones slippery and my jacket wet.

Ah, I see water! Finally!

Tough spot to reach. Very responsible.

Stopping along the way for a drink or snack was very refreshing. The distance might not appear too much, but all the rocks and hills sure take its toll. Even the local air force was apparently grounded due to conditions. I had brought my binoculars, just on the off chance they might be useful. Finally!

Of course, no hiking trip would be complete without Rico jumping in the river and sampling the local mud. This must be the highlight of _his_ trip. He even got his teeth brushed. Gargle, and rinse.

Finish. Looks remarkably like the start. Going in circles?

Gargle and rinse.

Old project and new motivation

2010-06-15T23:15:00.002-04:00

While I have kept myself busy (i.e. David Webber wrote quite a few books, especially on Honor Harrington. Well so did Elithabeth Moon and Tanya Huff...), with the highway-robbery gas pricess (pun and all) I have been trying to find if my car is using too much.

So after some obvious culprits checks and replacements, I seem to have come to the conclusion of needing to connect to the car computer. Or but an ODBII reader.

A little bit of tangent here. ODB seems like a rats nest of standards and updates. Wikipedia contains decent summary. One thing I took away form the research was the use of CAN in the new cars. Now this mysteriously useless network protocol has stumped me previously in other PIC (microchip) datasheets. But apparently, I have bought several PICs with CAN support already for the airplane. (I am worried if the protocol versions match; will find out eventually)

Long story short, seems like I need to get back and build that RC controller and leave two extra cables for CAN. Since the computer connection (UART or USB) is expected, had I had the RC controller, I wouldn't have to get any OBD readers.

The redesign is not surprisingly easier the second time around. Though now I am stuck with older parts and datasheets seem harder to find. (LCD datasheet has evaporated.) Also, the buck converter seems just as involved. Currently feel very tempted to just connect the 3.3 V regulator I have come by. And forgot how batteries get charged... Redesigning the Power circuit is no fun.

Maybe I am being to demanding, but for now am trying to build a power circuit that:

Detects low batteries (LVDIN in PIC seems useful)
Uses external power, if available
Recharges the battery if external source available

In fact, I will postpone this till later revision, will just stick to a regulator and recharge more often.

Great, now can go back to the more interesting XBEE and dsPIC30F3014.

Acceptance: the last stage

2010-06-15T22:46:00.003-04:00

While, it has taken me long enough, I am finally getting back to the airplane; think got over it.

I think I learned my lesson: got myself a 6TB RAID server (www.vopap.ca, still missing some services...) on an old computer. Also got an account with picasa to backup all the pictures I haven' t yet lost. (Surprised myself with 2.5GB worth of pictures!) Currently, backing up my designs to Ubuntu One since that seemed the simplest. Will post links later.

The name of the blog has also changed; I had bought myself a GPS60CSx after we got of the expected hiking trail up in Collingwood (Kolapore) and had to backtrack our steps. (In other words: Lost!)

So after tinkering with the GPS and Google KML, I now also want to post some of those maps. Now, as with all things Linux, have to connect GPS to my computer... So there should be (weekly?!) maps of Bruce trail hikes (eventually). Lately, Palgrave, Tiffany Falls, Hilton Falls and Dundas conservation have been the easiest to get too.

Hence the blog may become more diversified.

And finally, guess what, I signed back up for a Masters of Engineering. Glutton for punishment? Well, I am actually getting some use out of it... Maybe will post about some of the more interesting projects. (And I really wanted to have the excuse of having homework!)

Its been a while and disaster struck

2009-03-12T21:04:00.004-04:00

I figured it is time for an update here, as I cannot longer blame school for the delay... While I was busy with real work, my personal computer decided to crash the hard drive. But as Murphy loves twisting my tail, the backup drive has not been confugured yet. Whats worse is that I was at most a week person days of work away from a working hardware prototype and had already started printing PCBs...

Its been half a year now and for these or that reasons, I haven't revived the project yet. I am sure I will eventually, but now I am either very busy with work, feeling discouraged because of all the effort lost or just plain lack of enthusiasm. I still have the parts stacked in plain view so the flash of guilt is a daily occurrence.

Hmm, well, as psychologists say, "talking about it helps", so this must be a step in the right direction.

PS: googling for this blog, as I lost the bookmark, I came up with a project for which I did the wiring in high school... Not too many stupid questions! (preening in the mirror)

Back to school hold up

2008-01-10T19:42:00.000-05:00

Well, it that time again... You know, piles of homework, no sleep, deadlines every few days and a complete ruckus in the calendar. Don't know how much actual work I will get done on the RC-controller. Maybe will find some time to squeeze some work in, but otherwise this is again on hold till May. Just too depressing for words.
I expect the four software courses and the corresponding labs (Compilers II, Distributed Systems and Multimedia) will take up much of my time.

So happy I took all those useless statics and dynamics courses

2008-01-04T20:40:00.000-05:00

Visited some hobby shops last week to see what kind of trainer airplanes they have. (Trying to fly on a custom model without any experience isn't the best idea). There are several in the Markham area, prices usually above $150.
One of the reasons I wanted to see a trainer was to get a sense of sizing the receiver board. Well, 1.5"x1.5"x3" cockpit is about it (4' wingspan). That puts a stopper on much of my modular design. I intended to have modules on separate PCBs bolted together either with heatsink. Initial modules were to be:
-Power (Bucks, LDOs and battery)
-Motor (half H-bridge, servo control transceiver)
-XBEE router
-Main (featuring dsPIC33FJ256MC510, a 100 pin, 12mm x 12mm, TQFP, scary)
Design being like that, I can replace motor board to handle single or double DC or AC motor, replace XBEE with WiFi or custom interface and so on.
Unfortunately, size being what it is, I have to combine modules to minimize size.
One option is to combine a future IMU module with the Main Board. Its been quiet interesting week, seeing all of those motion integrals being applied to real things. While nothing definite is set in stone yet, an ideal IMU module would contain 3 gyroscopes (IDG-300 and ADXRS610=32pin BGA, brrrr) 3 Accelerometers (ADXL330 or ADXL103+ADXL203) and 3 magnetometers (HMC1052L and HMC1051ZL). Besides the price and IDG-300 needing a special order, there are many other things to consider.
First, as a requirement for the IMU, I wish to track position and attitude (6 numbers). While the calculations to obtain the requirements from the available 9 measurements are not quantum level, they are nothing to sneeze at (just working it out now, quiet a pain to visualize).
Next, one has to consider the drift and error inherent to all those sensors. The solution is a Kalman filter... An 'decent' explanation is available on wikipedia; good thing I just finished a probability course, because the math is still pretty muddy.
Next, there are all the vibrations in the frame affecting the measurements. The obvious one is the motor producing a given frequency of motor revolutions per minute. It makes the rest of the frame vibrate, probably at other frequencies. Bottom line, all the data has to be passed through an FFT, filtered, reverse-FFT and finally given to to the Kalman filter (Kalman filter is done in time domain, never heard of those before).
Lastly, all of that massive filtering has to be efficient, because the same processor is to be used to control the PWM channels (i.e. motors and servos), communicate through XBEE and other on-board modules. Lets hope those 40 MIPS will cover all of the processing (never mind that the whole design has to be power efficient...)
So, I am going back to all those rotation matrices...

Its a regular 5-cents-a-piece miracle

2007-12-28T21:46:00.000-05:00

It has been a fun or frustrating dozens of hours lately (depending on how late in the night it gets). Buck converters are surprisingly simple in theory. (See http://www.maxim-ic.com/appnotes.cfm/appnote_number/2031/ and AN793 "Power Management in Portable Applications: Understanding the Buck Switchmode Power Converter" from www.microchip.com). I was going to use a 555 timer to generate the saw and a dual-741 opamp, (and other pasive components of course). I have them by the dozen, so its not a problem. I have been accumulating many parts over the years, which led me to review my data sheet folder.

I found this chip in my parts-box, which was labeled as PWM conrol (probably to control servos or so I thoght). There are two chips of interest: LM3075 (more versatile) and TL494 both bought at http://www.supremetronic.com/ - a Toronto store at Spadina and College.

With LM3075, I can generate the 3.3V efficiently and according to the maxim website 5V LDO is just fine. (Apropos, I am using a 7.2V 2400mAh battery, giving me a grand total of 14 hours of operation on the ground side!). Nevertheless, I think I will leave the Power section on the breadboard and do the other sections and experiment with better setups later.

It all led up to this post!

2007-12-26T20:10:00.000-05:00

So its Christmas break, a great time to move the project forward (one of many actually, this one is just most fun). So I spent the last several days doing non-stop work (so much for vacations :() Well, I am almost ready to do the circuit layout. I tried PCB Artist, but it keeps on crashing on me after I got a sizable chunk done, so I restarted the layout from scratch again and gEDA it is. While the learning curve is not very gentle, I love the fact that I can automate a lot of my tasks.

I must have spent close to a week triple checking I can add all the extension I want later, so now I am down to making the PCBs (or so I thought). As of now, there is two boards on the ground controller: main and debouncer (to be extended to usb and lcd). I got the main all sketched out, the dsPIC30F, 44pinTQFP device all hidden by many rat connections, only to realize how much power would be wasted by using LDO voltage regulators. Not very good, when I made so many sacrifices for power. So now I am stuck again doing research on DC/DC and buck converters...

Well I am heading back to crawling the nasty Internet.

First Post

2007-12-26T18:58:00.000-05:00

I had this mad urge to brag about what I am doing, so, well here is this site.
Maybe couple of months from now, looking back, I will remember why this thing is taking me so long.

Anyways, the current history up till now:

My first design was going to be an FM controller, in the standard 72-73MHz range. Given the fact that there are 50 channels in the range, which should be software selectable, forces to build a complex processing system. I couldn't find anything off the shelf, so building involved a standard PLL, 10kHz reference frequency (from a counter powered by a Pierce oscillator at 10.24MHz crystal). The PLL should produce a frequency in the range of 2MHz to 3MHz. This can be mixed with a 70MHz reference (i.e. use frequency multipliers to generate). The mixer can double up as a power amplifier (Class D I think). The channel is selectable though the counter chip from the processor. (A lot of my research on frequency synthesis came from this wonderful website: http://web.telia.com/~u85920178/ ) The main problem then lay in designing a custom VCO. With back to back varactors for channel selection and message modulation, the problem is just selecting the right values for the components.
After several months of part-time fiddling with the circuit and trying to get spice to work on Linux or Windows, I scrapped the whole design to the garbage bin... I had several reasons: I am notentirely sure if my design is solid nor the tooling and research time to verify it. On top of that, modulation has to be done with a 8B/10B circuit so that PLL does not loose frequency lock (Not something exactly built into a PIC processor). I would be interested to know if the design idea was complete scrap or not. On other hand, I am happy to share more info about this design, if you are doing something similar.

My new design!!!

I found this nifty module called XBEE that communicates over the new ZigBee standard in the 2.4GHz ISM band. The module communicates over standard UART protocol, plus several pins for extensions. The modules are reasonably priced and have been tested for a decent distance. Whether this module will be fast enough to keep up with the controller is something I will have to find out by trial. The XBEE-1 boasts from a 115 kbs while I think I can encode all of my data into 1kbs stream.
With this module, the communication is bidirectional, so no worrying whether the battery is dying on the model, the controller will know in due time.
The plan is to build the circuit around this module, and ensure extensibility for later additions.