Another day, another circuit, this one is a little more complex than the LED/Resistor circuit I made the other week. Having read about transistors I decided to design and build a NAND gate. The final circuit is very similar to the one discussed in the XGS ebook (below is the original circuit schematic from the very same ebook – which I highly recommend; a print version will be out soon as well )

Aside from been a little blury the photo below shows my version of the NAND gate circuit built from two transistors, 3 resistors, two switches and an LED. The hardest part was finding a suitable 5V regulated power supply. I really need to buy a variable supply.

The far right of the image is where the +5V power is sourced, the far left is used as GND. The LED is connected to the +5V line via a resistor which results in the LED been lit by default. At the bottom right you should be able to make out the two switches, these connect the +5V supply to the base node of the two transistors (via one of the two 10Kohm resistors). Thus the switches control the input for the two transistors 1 or 0.

The collector of the first transistor is connected to the same resistor as the LED, with the emitter of this transistor feeding the collector of the second transistor. Finally the emitter of the second transistor is connected to GND.

The result of this is that when both switches are closed, the base of each transistor receives a sufficient voltage to start conducting from collector1 to emitter1 which feeds collector2 to emitter2 and finally running to GND. This gives us a working NAND gate. A 1 & 1 signal will result in a 0 i.e the LED will be off since both transistors are conducting to ground. Any other combination will result in a 1 as one (or both) transistor does not conduct, so we get a flow through the LED.

To most this probably isn’t the slightest bit impressive, its hard to appreciate the amount of background knowledge needed in order to understand how and why even simple circuit works, as well as analyse it; until you have done it yourself. So although it isn’t much to look at, I’m please with myself none the less

One lesson to take away from this is that it’s only once you begin to understand the basics that you start to finally realise how much more there is yet to learn. BTW I managed to get the joystick position to control the state of the LED that I mentioned in my previous XGS blog entry.

First off, Darwinia was fun for a while, but the demo just didn’t grip me enough to purchase the full game. I did like the mouse/icon combination for creating new units, although I wonder if anyone will struggle with remembering which icon they need to draw in order to create a specific unit?

I’ve been a big fan of call of duty every since it was released and in fact played it quite a bit last week. However, ever since [S&P] stopped playing as a clan COD has been missing something. Multiplayer gaming is great fun, but its much more tactical and enjoyable when your on teamspeak with people you know.

With the dissapointment of HalfLife2’s DM mode and Counterstrike been fun for a bit, but not a game I could play for long. I’ve been on the lookout for a replacement FPS. Unreal Tourny is good fun, but just misses something to keep me interested. HalfLife DM/TDM seems to have that “something”, I’m not sure what it is exactly, but it kept me playing from release right through to the end of last year. COD had it from a clan match perspective, but lacked it in quick pickup games.

Anyhow, a few friends have been telling me over the last month or two how good Battlefield 2 is. I’ve been holding off buying it though knowing that Quake4 (hope the linux client ships with it or is released soon) is just around the corner and that I’d need to dual boot windows. However since I’m also back playing eve-online, which is windows only, I may as well stick BF2 on it as well so last weekend I finally caved in and I’m glad I did.

3rd party stat pages added a lot more life to the original HalfLife, (although the hlccl ladder added even more) As with unreal tourny, Battlefield 2 incorporates stats as part of the game, but goes one step further by allowing your point score to unlock new weapons for use in multiplayer. Unlockable content always extends the life of a game, although even without it, I can see myself playing BF2 for quite some time.

The one thing that EA has managed to really get right with this game is the sense of team play. When you play as part of a clan theres a lot of team work involved, positions, weapon selection etc This generally doesn’t work well on public servers though as too many people will just play solo. BF2 gives you the ability to create your own squads of up to 6 players, to which you can issue orders such as attack/defend. In addition your 32 player team will have a commander who can issue orders to each squad. Although still not as tactical as playing in a clan, it goes a long way towards solving the problem of teamplay on public servers and really adds a new feel to the game.

My biggest complaint about the game is not the game itself, but the user interface. Trying to setup my key binds to E,S,D,F rather than the default W,A,S,D was much more of a pain than it should have been. If a key is already bound in any of the other 5 pages of key binds you get a message telling you, but rather than having the option to say “ok remove that bind and let me use this new one”, you have to go hunt all over and remove it yourself. Also to remove a bind you have to click on it, then press escape, which also happens to be the key to close the menu if you press it again..

In the end I found it much easier to open up the config file and manually change the keys. Its not that the in game binding gui is hard to use, just that it is really annoying if you want to make a lot of changes. Well that and the fact that its broken since crouch wouldn’t bind via the in game gui, it was only after manually editing the config file that it finally worked.

Still I’d rather have the annoying parts of a game be in the “setting up” stage rather than the “playing” stage.

So far most of my fragging has been on the 64 player [KIA] server, 85.236.101.35:16567, nice low pings and generally packed. If you’re a regular to the server, why not sign up to the KIA BF2 forums and get to know everyone else.

For those who already play BF2, I’ll end this post with a link to a quite funny video

Although I’m slowly working my way through the Design your own console ebook, theres a lot to learn, so I took a bit of a break last night and took a more hands on approach.

I built a very simple LED circuit and connected it to the XGS via the expansion port. That was the easy part, I then spent the next hour or two reading about the SX52 in order to program it to blink the LED on and off. It might not sound much, but considering I know very little about electronics and have never programmed the SX52 before, I’m pretty chuffed. In fact I’d rate the blinking LED achievment along the same lines as seeing your first triangle rendered via openGL, it doesn’t appear to do much but there was a lot of background work involved in getting that far

The XGS includes a lot of source code for a number of different hardware and software projects which I’m going to work through, although I prefer to try my own methods from scratch first. That way I can see just how far I can get from my own knowledge before getting stuck and having to refer to the working examples for hints/help.

So with that said, tonights challenge is to get the Joystick to light up an LED when you moved it in a specific direction. The circuit is about as simple as it gets, an LED, a resistor and a logic gate. Now I just need to find out how to talk to the joystick via the SX52.

Once I’ve built a more interesting circuit I’ll post up some screenshots. Although until I learn more about the overall hardware in the XGS the screenshots won’t be all that impressive

Does anyone have a time machine as I’d like to go back to just before the Northern Ireland/England kick off and tell myself not to watch it. The fact that England lost the game was dissapointing, however the worst part was how they played or rather failed to play. It just never looked like we’d score despite having the ball for most of the game. Northern Ireland however were playing a cracking game and as much as it pains me to say it, really deserved to score and win the game.

It’s not the end of the world though with Austria and Poland still to play, but tonights performance doesn’t exactly fill me with confidence. At least we are still in control of our qualification, still needing 2 wins. Austria should be 3 points, but then that’s what everyone said about Northern Ireland tonight. Looking at the tables, perhaps we could get one of the two runner up spots, failing that I think we’re guaranteed 2nd place in the group which puts us in the best of 6 playoffs, but judging by who we could potential be placed against, that would be a nail biter itself.

Anyhow, to cheer myself up (well its a good enough excuse ) I thought I’d checkout the Linux release of Darwinia, the second game from the makers of Uplink. If I don’t post an update to this blog soon, you can assume its a good game, either that or we’ve had another power cut