Well, here it is. The moment I have been anticipating for a good while: The boards came in and I assembled them. I made a few videos and took a few pictures. I won't post the videos yet since I am still going through them and making sure that I don't go and make a fool of myself.

After getting that far, I believe my camera died. Anyways, I assembled the breakout board and completed all the parts of the display. I did not solder down all the display modules to the pcb because I am going to be fiddling around with the resistors on the column sinks and I didn't want to have to desolder a display before being able to do anything else. The next day, I started testing:

As for testing and stuff, it mostly works. I made a few errors in both the hardware and the software, but I at least got the LEDs to turn on (I have not, however, gotten them to turn off properly...). My original program which should have been immediately portable to the hardware did not work so well and I ended up writing the entire display portion of the program in assembler: Apparently doing a variable bit shift on a 32 bit number takes up a very...long...time when compiled in C for the PIC18F. The main issue with the original program was that when I expanded the display size to 40x16 it suddenly had no refresh rate to speak of. This was mainly a product of the way I had organized memory. I had stuck the entire display into an array of long ints so that access to individual pixels could be done almost entirely by index. Sadly, when the size of the display was multiplied by 10 the computation of the bitmask began to take too long and made it impossible to properly refresh the rows. The assembly program I made to replace this organizes memory in the same fashion that I believe VGA cards organize the memory: Everything in one big long array which has no end-of-row designation and just wraps around when it is displayed. This ended up being much faster and hopefully it will work for the finished product.

As for the hardware problems, I have several. First of all, I made the primary mechanical engineering mestake when designing the package footprints: I didn't factor in tolerances. All the through-hole parts BARELY fit. In fact, I have to coax everything in using a craft knife to get the pins lined up exactly before the part will even go in. The button pins are going to have to be sanded down since there is a taper to the pins that was not in the datasheet which makes the pins too large for the holes. The next big problem is that the column sinks are behaving very strangely. After the voltage into the LEDs passes above 3.3V or so some of the columns just stop sinking while others stay on. I have a few ideas to find out exactly what is going on here, but I have no real plan of action to fix that as of yet. My final problem is that I somehow managed to lift a pad when soldering down a resistor. How this happened I am not sure, but I think it has to do with cheap board construction and using a solder wik that is too big. I barely managed to find a trace to solder to, so it is kind of fragile even with the hot glue I used to secure the wirewrapping wire I used as a trace extender. The next time I do this I am putting a via in EVERY trace that runs into a pad, even if it doesn't need one just for this sort of situation.

Anyway, aside from the mentioned problems the boards turned out pretty well. Olimex was fast and relatively polite. Their construction wasn't too bad (aside from the pad, but that may have been mostly my fault) and the boards shipped right on time and arrived right on time (to the day, in fact). Overall I would say this whole board experience wasn't bad and since it mostly worked I will say I didn't waste my money.

Thanks to my friend Walter Zarnoch, I now have a hosting plan that will work for the next two years while I am gone on a mission for my church. The plan is to basically keep my site up here while I am gone, hopefully getting hits and such from people interested in the crap on here, and then work on it after I get back. As for the future, I might keep this arrangement, but for all I know I might find out about a better arrangement later. Right now we share a hosting plan, splitting the cost 50/50, so its really not too bad at all costwise for a site I won't really be touching for two years.

Anyway, hopefully this works out...and I am sure glad to be off my grandma's website's host.

I finished modeling the entire board in blender today, so here are a few different views of the clock:

I created these images in blender by exporting images of the various pcb layers from eagle, compositing them in gimp into front and back images, and uv-ing then onto the board. All the components were done by looking at their datasheets of course.

Following the suggestion of a friend, I am going to open source a portion of the software (when it comes) and the display schematic. After I get the board and finish up the software I plan on releasing this as a kit. So far it is looking like the kit is going to cost somewhere between $110-$140. I would supply the board with the controller already soldered and programmed.

As it stands, the hardware features are as follows:

• 40x16 display with two LEDs per pixel giving 1280 LEDs
• Constant Current LED sink chips to prevent varying brightness problems with the display.
• PIC18F4550 Microcontroller running off the PLL on a 16Mhz oscillator giving 12MIPS throughput
• 41-pin high density board to board connector. A breakout board is included since development without one would be nearly impossible.
• 4 buttons. These are not connected to the display microcontroller, but can be read through the board to board connector.
• 8-bit parallel bus with CS, R/W, and CLK pins for communicating with the microcontroller in the fastest way possible. I have not yet decided on a maximum clock speed, but the clock is on an interrupt enabled pin.

The planned basic software features are as follows:

• Built in font(s). These would not be restricted by rows or columns and would be placeable by specifying start coordinates. I may also add the ability to have either user fonts and/or variable width characters.
• Pixel-by-pixel control of graphics. Each dot has 16 possible colors (4 brightness levels per color in each pixel...two colors). This would also allow direct memory "dumps" into the display for the possibility of animated things (assuming you have a powerful enough processor on the master side of the bus).
• Triple buffering to prevent overwriting the buffer currently being displayed. This may be extended to allow animations by switching buffers, but I am not sure if I have enough memory yet.
• At least 15fps throughput. 30fps is my target.
• Bootloadable using only bus commands, no POR required. I may or may not make the bootloader protocol public, but I am leaning toward making it public.
• More to come if I accomplish these and still have some clock ticks left over...

As for the board gerbers, I am going to keep them to myself. I spent nearly a year on the board design and I think I need to have at least some profit come of it before I release it to the world for some crazy board outsourcer to steal and clone at half the price I managed to get it fabbed at. I'll tell you this much: Eagle's autorouter can't handle the entire thing and there are well over 300 nets (not airwires...nets), so good luck.

Now for the schematic. Here you go:

Dot Matrix Display Schematic v. 3.5

Now, before someone goes on yelling about how much the BSS138 sucks as a MOSFET I guess I should say that I have replaced it with a much better one that can actually source the current I need it to. The BSS138 has a couple ohms of Rds_On, so I replaced it with a MOSFET that has around 0.25Ω Rds_On. Enjoy.

I have finally placed my order for the dot matrix clock. I chose revision 3.5 which had a surface mount crystal instead of the through hole version.

The only problem I have run into so far is that Olimex requires that the payment informatoin be faxed, so I have to use the fax machine at work to fax the order information. Luckily, my dad also works there and if he uses it for personal use there is much less chance of him being punished than me.

I just have to hope that they notice that all my solder side stuff is mirrored as that is the default with Eagle.

Well, just a short update here. I think I will probably be at home for another month or so, so I am going to go ahead and order the dot matrix clock display board. However, I need to decide between a surface mount crystal or a through hole crystal. I think my post on edaboard.com pretty much sums up my dilemma:

I have two possible versions I have been designing for some time now. Since it is looking like I am going to be home long enough to finish it I guess I should get it fabricated. However, one thing needs to be decided before I order it and that is whether or not I should use a Through-Hole or Surface Mount crystal.

Originally I was going to just use a through hole crystal, but after having a friend of mine look over the board as another set of eyes he pointed out that my crystal traces were over 3in long and had several vias in them. So, we identified a spot where a surface mount crystal could go with no vias and 0.5" traces. The criteria for fitting in this space was that the crystal had to be no more than 7mm long, 3mm wide, and 1.5mm tall. The obvious problem here is that nothing really fit in that space except for a crystal made by Abracon that is 3.2x2.5x0.7mm. Now the problem is size: is the crystal too small?

My resources: 0.015" solder, 1/32" spade tip (on a variable temperature soldering iron), solder wick, and a relatively steady hand (successfully soldered a .4mm pitch 64tqfp by hand without overheating it). Things I don't have: A magnifier, reflow oven Things I don't have but could get: Heat gun, solder paste

I don't have enough experience with this sort of thing to answer it myself and I really can't afford to buy two versions of this board. Is using a crystal this small really worth it?

Well, hopefully I will have that problem solved before the end of the month so I can place my order as soon as Olimex comes out of their summer break (for some reason, Europeans take a month long vacation from work in the summer...how odd...).

I was recently talking to a friend online after conferring with him about my dot matrix clock circuit board layout (now to rev. 3.4) when he mentioned that all people have to do nowadays to become a hardware "hacker" is to go buy an premade Arduino kit, attach it to some other premade piece of hardware, and load a premade program into it. More and more I have noticed this to be true. People no longer design and program their own stuff; they just buy something and say they hacked it together. Although I think having a standardized hardware to work with for embedded stuff like what I mainly do would be nice, I don't see the fun in assembling and programming somebody else's code into somebody else's device. What is the novelty in that? Where is the learning?

Even with this trend I have seen a few other examples of people coming up with something cool using premade hardware. A good example is from my History of Creativity class I took my first two semesters at BYU. At the end of each semester each student had to create and present a "creativity project" which showed creativity at some level and related it to the class. My second semester, one person in the class made something that absolutely astounded me in its simplicity and how obvious it was to construct. He basically made a multitouch enabled touch screen using an LCD with the backing taken off, a bunch of infrared LEDs shining into a glass plate, and a camera with a remote control bezel over the lens. He hooked up the webcam to the computer and used open source software to interface it to his computer as a multitouch human interface device (HID). He said it cost him about $200 mainly because of the monitor he bought and cannibalized. I was impressed. I was so surprised I hadn't thought of doing something like that. It's things like that with premade stuff that I find awesome. I had never before seen a monitor like this and from what he said it was the cheapest yet from a quick look around on the web.

Now why would it bug me that people are using so much premade stuff? Well, it puts people like me who design their own custom boards and software without using very many ready made libraries or a premade circuit layout into the shadows. It really does. When I say something like "I built this...take a look..." people then ask "Oh, where did you buy that?" I never buy stuff and say I built it. I believe the only kit I have ever purchased was a solar racer from solarbotics when I was younger. Other than that everything I have made was from my own self. The only time I buy something is because I can't make it for cheaper. People buying all this premade stuff kind of dulls the novelty of people using "custom" hardware on computers and the like. Its like what happened to CB radios: When everyone was on clogging up the channels the novelty was lost. Although I have never been into CB radios, I can see the point of that. Something is novel because its something few people do. When I first started with microcontrollers in 2005, very very few people I knew had experience with them. Now, its like everyone is buying their Arduino's and sumo bot boards, programming them with some premade software, and setting them loose as their own creation. Of course, there are the people who go buy these things but then make up their own projects with them. I happen to know one person who has a sumobot that he made from premade boards that he installed a webcam on, programmed some interface software, and now has a person (or rather, bright colored object) seeking robot.

The only way in my mind that people redeem themselves from falling into the bandwagon of buy it yourself fake hacker stuff is by expanding it to fill another need. Innovation is what drives the world nowadays, not invention. The only people who can invent things now are people with clean rooms and lots of money. Since there aren't many of those people in the world, the vast majority of us "normal" people have to suffice for innovation. Being in the United States, I would mainly refer to improving American innovation so that I can live in a country that has cooler innovations than other countries, but since the internet is a global audience its better to say that the world should be more innovative.

Saltpeter or KNO3

I am not in any way responsible for injury or damage resulting from this blog entry. Do not assume that these instructions are either complete or correct. Don't be stupid either; if you can't handle fire safely then you surely can't handle this safely.

Lately I have been doing small weekend projects which are generally cheap and fun. This past weekend's project, in honor of the 4th, was making smoke bombs. I found out from a friend at work that there was a store in milwaukee which sold lab supplies, including KNO₃ (saltpeter). I have been wondering how to aquire that chemical since I first read the anarchist's cookbook a few years ago. It is the main ingredient in many pyrotechnical compounds including gun powder, flash powder, and smoke bombs. So, I went to this store (Laabs, Inc.) in Milwaukee, near 30th and Wisconsin and bought two pounds of this chemical @ $7.12/lb. I got carded before I could buy it, so it is an over 18 sort of substance. It looks kind of like the rouded kind of rock salt that you can buy for water softeners.

The next ingredient was easy to get: brown sugar. I got the light brown kind, but apparently the dark brown kind works better. It cost me $1.89 at Pick'n'save (so far we are up to ~$18 on this project). Now that I have introduced the main ingredients, here is the illistrated tutorial:

Video and Pictures

Before lighting it

After lighting it

For once, I did something simple. I have always wanted to know how fast my potato gun shoots and I have also known how to find out, but I had never gotten around to actually building something to measure the speed of a moving object. I built this almost completely out of parts that are available at your local radio shack and hardware stores. The device consists of a 2" PVC pipe with two sets of infrared diodes/detectors placed in holes spaced a foot apart which are connected to a PIC microcontroller that I have programmed to act as a "stopwatch" measuring in microseconds. Once a time is captured, the value is written to EEPROM for later gathering at the computer.

The Ghetto Chronometer. It looks rather like a pipe bomb doesn't it?

I have just installed Ubuntu 9.04 Netbook Remix on my Acer Aspire One and I have to say it is pretty awesome. First of all, it really does boot in 30 seconds. It took 28 seconds to get to the login screen which is most of the booting. From there it was just the normal login stuff, so it was very fast. Secondly, the Suspend/Resume is also very fast. Fast fast fast. That seems to be the point of this distro. Anyway, I'm definitely keeping this one on my computer.

Ubuntu 9.04 Netbook Remix