Arduino!

So I finally bought myself an Arduino Uno. I have been wanting to get more into micros and embedded computing for a while, but did not know how. Arduino is the perfect solution for relative beginners such as myself. Within a week of buying it, I had a project in mind I wanted to work with. Wanna hear it? Here it go:

I found the WiiChuck Library, and decided to make a little project which would take accelerometer data from the Wii Nunchuk, do a couple of calculations, and show the result on an LCD. This would give me some experience with Arduino, an external library (WiiChuck), and an internal library (LiquidCrystal). I'll try to update the results here as I make progress.

Power Supply Design

For the project I'm working on, I need to design a power supply which results in an output voltage of 3.8V. I think I'm going to have the GE864 chip controlled by another micro in order to more easily control the timing required for power (turning the chip on and off requires a 1s pulse, restarting requires a 200ms pulse on a different pin).

Although I haven't selected the microcontroller I'm going to use yet, I have designed the circuit which will interface with its output, which corresponds to the GE864's input (ON or RESET pins). I have designed my power supply circuit with an input of +5V from the micro and an output of +3.8V going to the GE864.

Right now I'm getting power from an old PC power supply. I found the pinout for the main harness and switched the green and black wires in order to turn it on and off. Using my multimeter, I measured different output voltages between pairs of wires. Some were +12V, some were +5V. I decided to start with the +12V coming from one of the floppy connectors.

I ran power from the yellow wire on the floppy harness to the power block on my breadboard, and did the same with ground. To clean up the input some, I used a 100uF electrolytic capacitor. In order to bump down from +12V to +5V, I just used a 7805 +5VDC Voltage Regulator from Radio Shack (way overpriced, I know, but instant gratification). I chose to go this route instead of just using the +5V from the PC's power supply because I wanted a more accurate reading. Coming directly from the supply wouldn't have given me as close to +5V as bumping down with the regulator.

So now, I have a clean +5V to work with. But I need to get to +3.8V. For this, I decided to use the LM317T Adjustable Voltage Regulator, and I'd just design a circuit around it.

I just decided to use a good old-fashioned voltage divider. The LM317 was too tricky. The voltage divider was straightforward and since I was on campus, obtaining the parts was free, as opposed to  unnecessarily expensive.

Designing a circuit with my specifications was not difficult at all (Prof. Dragon is the MAN!). Here are my calculations:

Vin to the voltage divider was my +5V from the voltage regulator. Vout is the +3.8V that I need to power my chip. I selected a random value for R2 = 3k and just calculated R1 from the voltage divider formula.

Here's the schematic representing my circuit:

I used the 1N401 diode to protect against backwards current and the capacitors to filter the input and output. My theoretical output was 3.75. I actually measured 3.73, which should be fine for this

SO glad I got this working now! Next I can work on how I actually want to go about turning the chip on and off. I'm thinking of using a separate micro to send ON/OFF signals to the GE864 instead of doing it manually.

Project Schematic

I'm working on a project using the Telit GE864 chip, and have been having a hard time learning PCB design software so I can make the schematic for my circuit.

I went back and forth between PCB123, ExpressPCB, and CadSoft Eagle. Although PCB123 and ExpressPCB seem like fine products, I eventually settled on Eagle because the others are proprietary. If I designed my schematic and board with their software, I had to buy from them (I think one of them has a free pizza offer when you order a board, which was tempting, but didn't quite seal the deal). And, from what I understand, Eagle is used in industry, so I figured it would be good to get familiar with it anyway.

My trouble was, I had never designed a schematic around a chip before. The only experience I had was designing simple circuits in MicroCap with simple components (resistors, capacitors, diodes, power/ current sources, etc), but nothing with an actual chip.

I recognize "the cloud" as an invaluable resource for engineering/ programming help. I registered for the forums on Sparkfun. Within 30 minutes, I had a reply. Within an hour, I had my solution. Someone pointed me in the direction of the Sparkfun tutorials, which are immensely helpful. This one, in particular, described how to create a breakout board in Eagle. . . . which is EXACTLY what I needed to do.

I found that instead of creating the library for the chip I want to use, I could just download the one the geniuses at Sparkfun had already created. While this simplifies my task greatly, it still leaves a great deal to be learned, which I completely appreciate!

Now I'm researching more on the chip and deciding what type of power supply I want to use. I may just design schematics for all of the suggested supply circuits in the GE864's instruction manual, for more experience with Eagle.

I'm very excited right now!

Replacing a Zune 80 glass screen

My Zune has a history of breaking itself while I'm fixing it. Last time I took it apart, I got it to WORK again, but cracked the screen. This weekend when I was in a portable-electronics-screen-buying-and-replacing mood, I decided I'd grab a Zune glass as well.

So, let's get started. For the sake of completeness, I'll go through the entire process, even though it's partially documented here.

Required

• Zune 80/ 120 (I guess the HDD size doesn't matter. Second generation or above, non-flash, non-HD (where HD stands for High Def, not Hard Drive))
  
• New screen
• T4 screwdriver
• Tiny electronics flat head screwdriver (I prefer size 2.5 - 4.5) or a case opener tool

Procedure

1. Remove the plastic clip from the top of the Zune with the flat screwdriver or case opener tool
2. Unscrew the two T4 screws at the top of the Zune
   
   
   
   
3. Carefully, take the flat head screwdriver and gently pry, starting at the top where you just removed the T4 screws, and work your way all the way around. What you're doing here is undoing the clips all around the casing. **This is the part where I cracked my screen last time**
   


4. At this point, you should be able to remove the entire aluminum back, and see the Zune's nasty internals.
   
   
   
   
   
   
   
   
   
   
   
   
5. Remove all that #$%@ tape!
6. Take out the 6 screws holding down the motherboard. There are three pairs, each pair is a different size. Keep them in order! *Note - when you take out the screws on the side, a metal clip will also come loose.
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
7. For safety's sake, I removed the hard drive at this point. Lift the black flap on the ribbon cable connector. Use the flat head screwdriver to gently pry this up. Start from one end, and work your way to the other. This is a long tab, and will likely take more than one (probably two) pry-points to lift. (I know the picture shows the screwdriver in the middle. . . . disregard that :-|. . . . it was only for illustration's sake)
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
8. Now, gently pry the board up with the flat screwdriver. Go evenly and CAREFULLY all the way around until you can lift the motherboard out of the case.
   
   
   
   
   
   
   
   
   
   

Whew. . . . now for the hard part.

Removing the Glass Screen from the casing

I won't post the failed attempts and pictures of me trying to get this glass out; I don't wanna upset those who get queasy at the sight of blood. . . .

Nah, just kidding. Bud it did take me some time to figure this out. The glass is held in with a strong adhesive. I tried pushing it out, scoring around the edges, and prying. Some of these worked better than other, then I realized that I could just heat it up with my heat gun! Then I realized that I don't have a heat gun. Then I realized that my wife does!

HA! lookit the guy on the box

Apply heat to both sides, pressing the glass out every so often. After the adhesive melts enough, you're in business!

Remove the white tape from the new glass, replace the old one with it, and heat to activate the new adhesive. Put everything back together, and you're in there like swimwear!. . .

. . . . unless you put the hard drive ribbon cable on backwards. In which case, you'll get this screen. Fix it, and you'll get this one!

Replacing an iPhone 3G glass screen

So lemme tell you about my crappy weekend. It all started Thursday night. I had just come back from a lovely night out with the Missus. I took my iPhone out of my pocket and threw it down on the bed. Unfortunately, I missed the welcoming, soft mattress, and hit the cold, hard, unforgiving wooden corner of the bed. The result: a shattered glass screen AND LCD.

To make a long, sad story short, I just opted to buy a new iPhone from the Apple store for $199 the next day instead of paying $150 for new glass and LCD. I traded them the broken one and they gave me the discounted price. I was in a rush when I left the store, so I couldn't stop by Micro Center and buy myself any screen protectors. And I wasn't going to pay the ridiculous prices for any accessories in the Apple store. I didn't want my screen to get smudged, so I didn't put it in the old case I had. So I just went home, happy with my new, unprotected iPhone.

Saturday, I was with my 2-year old nephew. I leaned over to pick him up, and out of my shirt pocket slides my brand new iPhone 3G (no S), kissing the cement floor face first. The result:

So, in a matter of 2 days, I had managed to destroy two iPhone screens. This time, since it was just the glass, I just bought it and decided to install it myself. Here's how:

Required:

• Broken iPhone 3G or 3GS (The glass and LCD are separate on the 3G models. On the OG, they're glued together, making replacement difficult)
• Replacement glass screen
• Flat head screwdriver, size 1.5 (or a case opener tool if you're so fortunate to have one)
  
• Phillips screwdriver, size 000

Procedure:

1. Turn off the phone. This is to prevent shorting of any circuitry once we start digging in the iPhone's guts.
2. Using the Phillips 000, remove the two screws from the bottom of the iPhone

3. Use the 1.5 flat head screwdriver or the case opener tool to pry the screen up. Place the blade in between the chrome and the glass and separate the screen and LCD assembly from the back of the case.
   

4. Carefully tilt the screen/ LCD assembly up so you can see the numbered connections on the board. They are numbered 1, 2, 3. Remove these from the board in order. 1 and 2 are relatively straightforward, just use the flat screwdriver to pry them loose. The connector for 3 has a tab you must lift before it slides out. Proceed carefully.

5. Once the cables are disconnected, we can separate the LCD from the glass. Using the 000PH, remove the 5 screws indicated in the picture below. Some are covered with black tape, so you'll have to remove that.
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
6. Slide, then lift the LCD out of the glass. If you lift it without sliding, you may bend or break parts of the assembly.
   
   
   
   
   
   
   
   
   
   
7. Replace the broken glass with the new one, replacing all the screws in their proper places.
   
8. Reconnect the ribbon cables.
9. Slide the glass/ LCD assembly back onto the phone's back.
10. Replace the two screws.
11. Use protection! Don't wanna get burned again. . . 

Hacking into my Zune. . . . literally

OK, so over the past couple of years, my Zune 80 and I have had a love/hate/hate/hate/hate/love/hate/hate relationship. No matter how that may look in WRITING, the good truly has outweighed the bad. So when it zonked out on me this final time, I felt a moral obligation to try to save her (yes, "her". . . I actually named her Zoey). And since Zoey was [literally 2 days] outta warranty when I first started having this problem and Microsoft wanted $159 for service, I decided I had nothing to lose by finding a T4 screwdriver and trying to fix the problem myself.

The problem: I couldn't seem to turn her on anymore, no matter what buttons I pressed (heh heh). When I pressed the "Play" button, I got the "low battery" indicator image. While plugged up (AC or USB), the "charging" graphic flashed, but the OS would never load.

~~~...::flashback::...~~~

This had happened before, and I had simply given up on my baby. I just put her away in the box and used my PSP for a music player. I was sad, but it did the job. After leaving Zoey in the box for like 2 months, I came back, just to see what would happen, pressed the play button, and VIOLA!* She came right on for me.

~~~...::/end flashback::...~~~

*I know it's really voilà. . . just more fun this way

 ::siiiigh:: Back to reality. This time, I tried that and no luck. After exhausting all software options, my logic was that there must be something wrong with the battery. Maybe if I disconnected and reconnected it, then it would function again.If that didn't work I would go ahead and buy a replacement battery. Sooooooo, after a little deliberation, and a bit of mental preparation, I went ahead and got started.

Note: Though it'll go without saying, I didn't have a camera while actually taking it apart. This is more of a journal entry than a tutorial.

Procedure:

I got an idea of how to do this from Rapid Repair's Zune disassembly guide. I improvised some of it as well, as you'll soon see.

1. Since the plastic cover at the top had already been lost, I didn't have to remove that. I just started by removing two T4 screws at the top of the unit.
 
2. Now, this part was pretty tricky - removing the aluminum back. I suppose there should be an intermediate step describing how to loosen the backing first. So maybe I wouldn't have CRACKED MY SCREEN!
 
3. To loosen the casing, I took a very slim flat-head screwdriver, inserted it between the front and back casings and twisted slightly. There are clips holding the external case together. Twisting the screwdriver essentially gently unclipped them, and methodically pried the case open. . . too bad I discovered this procedure AFTER I had already CRACKED MY SCREEN!
 
4. Now, once the casing was open, there was a lot of tape everywhere. Instead of just going on a tape-removing rampage, I drew a picture of what I had, just in case some wire or ribbon cable got disconnected in the process (which, inevitably, it did).

I took this picture after I got it apart (obviously). Although it's pretty crappy quality, you can see I flipped the hard drive over to have a better look at the battery connections.

It was here, when I saw one of the four wires (black, blue, red, white) leading from the battery to solder points on the board had come disconnected. I'm not sure if this happened with handling or if it was the cause of my problem. If it had come apart after I opened the Zune, then I still had accomplished my goal of disconnecting the battery. If it was already apart, then I had found a problem. Whatever the case, I knew it needed to be soldered back on.

It was a relatively simple solder job. I used some fingernail clippers to strip the blue wire back some, then heated the solder joint and set it in place. Turned it over, and saw the beloved Zune boot logo!

YIPPEEE!!!!

But that's not the end. . . after I got Zoey all buttoned up again, I noticed a new issue - the little "Hold" icon in the bottom of the screen was lit, and no button presses registered. Great. I pressed the Zune in a certain spot, and noticed while applying pressure directly over this particular place, the icon disappeared. So I took it apart again.

Here's the drawing I made:

 

At this point, I noticed that the ribbon cable which controlled the hold functionality was not being snugly held in place. I pressed down on the ribbon cable connection to the board, then toggled the hold switch, and it worked fine. I replaced the tape, put the zune back together, and all is well again. . . . . except for the cracked screen.