SHIIAAATTTT.
It’s not working. Damn thing decided to crap out on me ON THE FREAKING PCB after assembly. A criteria I didn’t meet? Yeap. It didn’t go past 10V peak to peak. It barely brushed past 5V p-p. Oh Em Gee. Screw it. Handed it up last Thursday, with my project report following it on Monday next week. I hope that my lecturer will accept my half-arsed reason for it not working. Not fluff and bullshit, mind you, but proper analysis on the problem and why the damn thing didn’t work. But still, I call it half-arsed reason because there wasn’t any proof of the failure attributing to the fact, it was more like I tied the failure to the fact through self-analysis and observation. Should work? I hope.
Btw, the project website is up, albeit a temporary one. It’s still ‘work in progress’, but it has my group picture as well as (soon I hope) the project description. Project group name = RC2.
Left to Right : Shang Wen, Me, Robert Li
Endeavour 2007
ECD 3 though, is moving towards the end (thankfully!) with the project on the final dregs for the hardware and software section. All that will be left then is the report, which I hope I will write in a state of mind that does not lean towards fluff. Or plain long-windedness.
Project work? Don’t ask. We had to scrap our 5 weeks of work today when the algorithm that we were using right until 6 hours ago had to be scrapped. Complications in the algorithm were the main cause, and we hammered out a simpler algorithm that wasn’t so memory hungry and might even be faster in the end. Now, we will be concentrating on our PCB design as a prototype as well as having it as a development board.
Ah well, hope I don’t fall sick again.
KW
One of my favourite subjects. The lecturer is fun, and the projects are tough but they are exactly what I like to do. Lucky for me, I did not take this subject in my third year (this subject is a third year subject) but I opted to do it this semester as an elective instead. Last year it was taught by another lecturer, one who wasn’t as fun as my current one. Even so, he’s gonna be teaching us for the second half of the semester. You can’t have everything can you? Hehe.
This year, Graeme (my lecturer) had this great idea of giving us a project that we have full control of. Of course, datelines are controlled by him, just that we have free reign on our project design. We were asked to design an audio amplifier with the following specs:
- operate from a single 15V external power supply
- have input impedance > 10k ohms
- have a 3dB frequency response (nominally) 400Hz – 18kHz
- have mid pass-band voltage gain with magnitude of (nominally) 18
- be capable of driving an (external) 68 ohm load with at least 10Vpk-pk
- AC coupled input and output
Following components are available:
- LM741 op-amp + socket
- 2N3904 (NPN BJT)
- 2N3906 (PNP BJT)
- 1N14148 (small signal diode)
- 47 uF 25V elec. Capacitors
- 68 ohm 0.5 W resistor
- PCB pins
After preliminary design on PSpice, a simulation tool for circuits, I managed to build up a circuit that fit the required categories. Actually implementing it on the breadboard gave me lots of grief though. As usual, a lot of things are idealised in simulations, and this ‘idealisation’ sometimes kills the design. After many optimisation processes, I finally am able to construct a circuit that is barely able to meet all required criterias.
After that stage, PCB design came. Implementation was fairly easy (for me) and I handed in my design last Tuesday. The PCB boards came in on the following Monday (technically yesterday since it’s 12.48am for me now) and I completed soldering the thing that day itself. I have not tested it yet though. *Shudder* Knowing the problems that plagued me when I worked on the breadboard, I hate to think the debugging issues associated with this. Ah well, these are the pics of my completed project on PCB.
PCB is missing the op-amp, which is supposed to sit here: (the op-amp is still on my breadboard) – Finger looks fat (check out the PCB size on the next pic)
Size of the PCB as compared to my Sony Ericsson Z800i. For those who haven’t seen the Z800i, the size of the board is 1.95″ x 1.7″. Use a ruler. Small eh?
Now you know what actually sits in those big ass speakers around :) Implementation and design might be slightly different, but the idea is the same.
KW
Hehe… Finally pictures for my temperature sensor!! Unfortunately i don’t have the luxury of friends taking photos during or after my presentation, so I can’t show you a picture of me in smart clothes. Nevertheless, here’s the project picture. :)
Picture of the components (lower layer):
KW
Hehe thanks so much to Sian Siew for updating my blog theme. The old one was nice, but the column width a little too small to do any serious blogging. (I don’t want my blogs to be merely 3 lines thick =/ )
Ok… Back to topic. Being a final year student, I’m allocated a project to work on. Along with 2 other teammates, our project will be a year long thing with a final year presentation to the public as well to our supervisors.
Project Name: High Speed Vision System. Project code: RC2 (RC standing for Robocup). Below is a project description by Robert Li, one of my group members:
“One of the most important aspects of a robot is its sensing/vision system.
This project is to realise sophisticated object recognition algorithm on hardware which is designed to be used on robotic platform but will also be compatible with a board range of industry applications. Highly accurate ball tracking and moving target recognition at high speeds is the ultimate goal of this project.
By using a high resolution video camera and a specially designed mirror, robots are able to “see†a 360 degree image (essentially a top down view of a defined area). A Field Programmable Gate Array (FPGA) is used as a primary mean of speeding up the process of object detection. It’s extraordinary concurrent processing feature allows processing different coloured objects simultaneously and pipeline processing each pixel as it comes into system. External Synchronous RAMs are used to support large volume of data while maintaining high speeds.”
Since we were needed to submit our own project descriptions, I believe the text above neatly summarises our project aims in a nutshell. That being said, the complexity of it is enormous as we are going to integrate the algorithm into hardware (the algorithm being realised last year by a group of students, Ni Ma and Nathan Williams. Their project website: http://fpga-vision.sourceforge.net/
Current issues that we are addressing:
- Bus size to interface with the processor board. (which is managed by Boon Chong Khor, Nicholas Seng Tatt Yeoh and Shubham)
- Building our very own development PCB board since the RAM chips used in the stock dev board is DDR-RAM and we’ll be using SRAM.
- Timing issues with processing frames ‘as they come’ (hence high speed) as well as application consideration (the speed which is required by the application)
The vision system that we will develop will ultimately be used in the robots that are representing my university in future Robocup tournaments. As I go along with the project, I will post some pictures of our progress as well as the actual robot itself.
Ok… Delving into something that you use everyday (I HOPE!) and complain most of the time about it. The internet.
To be precise, it’s the connection rather than the internet itself. To most users that have started using the internet not long ago, I bet you guys have not even heard about dial-up. Dial-up was somewhat similar to the fast ‘cable’ connection that many users are using right now, albeit much slower. The fastest connection back then was using a 56k modem.
So… How far have we leaped in terms of connectivity? Internet pages that used to load so very slowly in the yesteryears now materialise almost instantaneously once called. In Australia, the fastest connection that can be afforded by average users would be the ADSL2 line, sitting comfortably at 24Mbps (Mega-bits per second). This means, on average, the speed should hit about 2.4 Megabytes per second. If you’re downloading a song which is about 6Mb (depending on encoding and quality) it takes about 3-5 seconds to download that song! Fast huh? A cheaper alternative (and the one I’m using cause damn Carlton is limited by the cable type to hit ADSL2) would be ADSL1, which hits a maximum speed of 1.5Mbps. This translate to about 150kb per second, which is a far cry from the ADSL2 line, but still good enough for the things I do.
How do these all work though? How are we able to move from a 56kbps to a 1.5Mbps line without ripping all the cables out of the ground and replacing them? (The same does not apply to 24Mbps since we NEED to rip the cables out of the ground and replace them) The answer lies in termination schemes. Now the question is… What are termination schemes? To put it in short, they are means whereby a transmission line is terminated. Then you’re thinking again… Why must they be terminated? This is a semi-complicated issue, but I’ll try to simplify it as much as possible.
Imagine yourself walking from where you are sitting right now, to say, the toilet. This is assuming you’re sitting comfortably at home, at which the toilet should be at a comfortable walking distance. Now, take that distance, and imagine an ant walking from point A to point B. Far huh? Well, this is what happens in transmission lines. Data bits are transmitted at a rate so fast, that even short wires seem long. This actually translate to the delay and the limitation on how fast data can be transmitted. With these kind of fast transmitted signals, wires which we always assumed to have almost negligable resistances, inductance and even capacitance, now have these properties ‘magnified’. These properties must now be taken into account when transmitting data.
This magnification of the impedances (I will now lump all of them into this term) will cause power loss, and at a worst case, ringing. No, this isn’t the telephone kind of ringing! Ringing occurs when the modelled capacitor and the inductor resonate with one another. Think of an opera singer hitting a note that breaks glass. The principle is the same since the fast changing voltages across those capacitors and inductors (due to the fast changing data transmitted) cause them to resonate. This causes unwanted signal propagating to and fro the transmission line. By limiting the rate at which the data is transferred, we can then avoid corruption of the data transmitted. This would be why we need to rip cables and replace them if we were to transit from ADSL1 to ADSL2. The properties of the cables would inherently be different.
How about signals ‘bouncing’ off the receiver end? Hmm… This actually comes down to refraction. Remember physics in high school? Optics? Well, the same principle applies. Light can be thought of as an extremely fast oscillating wave. By passing it through 2 objects of different medium, (a good example will be from air to water) the light beam will actually ‘bend’ and ‘reflect’. This depends on the angle at which the beam enters the 2nd medium from the first. If the angle is 90 degrees, the reflection will be superimposed onto the transmitted beam, with the ‘bending’ effect unable to be seen. The same actually occurs in transmitted signals. Due to the receiver end having different impedances compared to the transmission line, the signal actually ‘bounces’ back to the transmitter. This obviously corrupts the next signal that is to be transmitted.
The scheme I’ve described is called ’shunt termination’ or ‘end termination’. There are other methods like ’series termination’, ’split termination’ and ‘AC termination’. Each of them have their own pros and cons, and should be applied only where appropriate. Actual analysis of these terminations actually involves a lot of electrical terminology, and an average layman would not be able to follow anything I’ve typed out.
By having a good knowledge of the transmission line, current methods are able to obtain an optimum speed at which data can be transmitted. Ripping the cables out and replacing them will have to happen sooner or later though, since technology is always improving and that seems to be the only way to advance along with it.
KW
P/S: If you feel like I should just delve right into the mechanics of things, feel free to say so. My next posts will then concentrate more towards the basics of things, then moving on to the more advanced sections of electrical engineering.
Ahhh finally… Design Lab is done and over with. Overall the project was fun to work on and the group was certainly a pleasure to work with. We had our presentation which we felt we did pretty well, and it was sad when I had to pack up the stuff that we used throughout the semester. Oh well… At least I’ve got the veroboard (it’s working!) to remind myself of the experiences I had…
Looking at other ppl’s blogs and stuff… Made me wonder what should I actually base my blog on? Writing stuff about my everyday life is fun… but it gets boring and monotonous after a while. It’s not like I lead a very eventful life, with extraordinary things happening everyday. And I certainly won’t post up on my personal experiences with my gf. Nope. That kinda thing is private. :)
So… I sorta decided to post up on stuff I actually learnt, which I hope will open up the eyes of people who see my blog, on what am I doing and how it applies to everyday life. And… what I’m studying now has EVERYTHING to do with what you guys see, hear and use. Electrical Engineering is the source of technology that provides people with comfort and ease of doing anything, right at their fingertips. Interesting huh?
KW
Happy birthday boss! 22 liao… When getting a gf? Hehe… Anyways, thanks for all the fun that we had, and looking forward to lots more :)
Happy 22nd Birthday :D
Ahhh ok. A much needed break that will not feel like one. The design lab project has yet to be finished, with a few more stuff to solder on, and probably gonna make ANOTHER one since we might be adding a few things here and there as wow factors.
But then again… there’s no need to wake up early now. Yay! Sleeping like a pig ftw.
It’s coming along very well now, with a few things to finalise, and just the program to get working. We missed the PCB design deadline (screw it) so we are definitely implementing our project on a veroboard, with a prepared draft for the PCB design to net us some extra marks.
I hate debugging :(
T3h B1gg3st N000b. Me. Spent a week trying to figure out what was wrong with my circuit and code. The microcontroller was not responding, so that really worried me and Khor. We went through the data sheets countless number of times, trying to find a clue to what went wrong.
Then Khor found it. A misplaced wire. Mclr, which was supposed to be tied to a HIGH, was tied LOW. And guess who set the circuit up? Me. /cry. We weren’t set back by that much though, but this means we won’t get to present our circuit on a PCB. Ah well, a veroboard will work as well.
