Electronics and Embedded Programming V3

[Chipset]

Welp it seems the revived cells are dead after all, twice I left it charging for about 2 hours and twice it died roughly 20 seconds after removing the DC jack. The battery section in the bios is somewhat confusing as all the values have a one or two letter marking and I've been unable to find any kind of documentation. Though to be fair I didn't look for long. Still, I found what is almost certainly the cell voltage in millivolts as it's values are 3500-3700 when discharging and approaching 4000 when charging and what I think is the capacity as its values are 2500 ish when it's been charging and C3 (the revived cells) value plummets while discharging and is at 100 ish when I reboot after plugging in the charger.
From experience in reviving a compact digital cameras li-ion battery, I know it can be brought back to roughly functional condition by repeatedly charging and discharging but I think I'm just gonna order two 3.7 volt li-ion cells next time I order from deal extreme. It's not a lot of money and it saves me a ton of tedious work.

[DrLuke]

[QUOTE=Lapsus;34968560]I wanted an excuse to mess with tables :v:

I'm still minorly worried about that bit of exposed wiring on the rectifier though.[/QUOTE]

Just tape over it with 3 layers, and it'll be ok.

[Chryseus]

Exposed wiring is not a problem unless you happen to be poking around in it while it's switched on, the rest looks pretty decent to me.

[MIPS]

Scavenging got me the 3/4" CRT I have been searching for. Just needs +6v DC and composite video.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2550.jpg[/IMG]

[DrLuke]

Wow that's kickass

[VistaPOWA]

[QUOTE=MIPS;34984443]Scavenging got me the 3/4" CRT I have been searching for. Just needs +6v DC and composite video.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2550.jpg[/IMG][/QUOTE]

Was it a camera viewfinder?

[benjojo]

[QUOTE=MIPS;34984443]Scavenging got me the 3/4" CRT I have been searching for. Just needs +6v DC and composite video.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2550.jpg[/IMG][/QUOTE]

That is... Really cool.

[MIPS]

[QUOTE=benjojo;34990880]That is... Really cool.[/QUOTE]
It also uses less power than any 640x480 LCD panel I know of. It even overscans if you use a 9v battery.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2558.jpg[/IMG]

[Chryseus]

Just a quick reminder, the MIT 6.002 free electronics course has now started, if you've not enrolled you best do so right away.
[url]https://6002x.mitx.mit.edu[/url]

[demoguy08]

[QUOTE=Chryseus;35006402]Just a quick reminder, the MIT 6.002 free electronics course has now started, if you've not enrolled you best do so right away.
[url]https://6002x.mitx.mit.edu[/url][/QUOTE]

This. Also, I created a thread in General about it: [url]http://facepunch.com/threads/1168312[/url]

Figured it sits better there than here in the programming forum.

[editline]5th March 2012[/editline]

Well, if it dies in General then I'll ask a mod to transfer it here I guess

[LoneWolf_Recon]

Crud, school still got me. Guess I'll just stick with their youtube videos

[VistaPOWA]

Damn, electronics is a very danhgerous hobby.

I just broke my finger accidentally...

By dropping a 5kg transformer on it.

[VistaPOWA]

Just learn the colour coding, way faster than visiting a site every time you need to know the value of one.

[MIPS]

Wasted the evening and a 9V battery dicking around with that tube. It's a total bitch to photograph.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2577.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2572.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2569.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2574.jpg[/IMG][IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2581.jpg[/IMG]
Hmm. The image is displayed in reverse. Probably because the viewfinder was angled. I'll have to find another one where the tube was inline with the viewfinder which means I'll be looking for an even SMALLER tube.

[Tw34k]

Could you somehow mirror the input feed or un-mirror the output?

[MIPS]

Everything on the analog board revolves around a [url=http://www.datasheetarchive.com/BA7125L-datasheet.html]BA7125L[/url]. That I'm aware of, the only way to flip the video back is through a scan reverser but there must be a way to do it on the PCB.

[Ddrl46]

[QUOTE=MIPS;35032141]Everything on the analog board revolves around a [url=http://www.datasheetarchive.com/BA7125L-datasheet.html]BA7125L[/url]. That I'm aware of, the only way to flip the video back is through a scan reverser but there must be a way to do it on the PCB.[/QUOTE]

Or you could just flip around the deflection coils.

[ROBO_DONUT]

Or you could view it through a mirror.

[Chryseus]

Well I've had a play around and I thought I'd give you guys my impression of MITx's 6002.

The course layout is pretty good and covers quite a bit of content, the emphasis on circuit analysis in particular is excellent, however it does assume that you have a decent knowledge of electricity, physics and mathematics, regardless you will need to do quite a bit of independent study.
Doing the exercises and homework that's assigned each week is pretty easy, it even includes a very nice little circuit simulator.
To prevent cheating the questions are randomized which is quite nice, although it certainly does not prevent you from using the circuit simulator to get the correct answer.
The textbook 'Foundations of Analog and Digital Electronic Circuits' is provided for free as well, you can only view it online however as the book is still sold and goes for a whopping £55~ on Amazon, almost worth enrolling just to read the book.

Overall I'm pretty impressed with it because it has given me more motivation to improve my circuit analysis skills, for absolute beginners however it may be rather difficult to keep up.
The first homework needs to be in by 16 March so you still have time to enroll.

Also I got the best question ever:
[quote][b]How many Joules are there in a BigMac?[/b][/quote]

[Goz3rr]

[QUOTE=Chryseus;35035650]
Also I got the best question ever:[/QUOTE]

What's wrong with that?

[Chryseus]

[QUOTE=Goz3rr;35035723]What's wrong with that?[/QUOTE]
Nothing ?
I just was not expecting it.

[phazmatis]

Hey I have one of those tiny CRTs someplace... I'm glad someone figured out how to wire them up.

[Foohy]

[QUOTE=Chryseus;35035650]
Overall I'm pretty impressed with it because it has given me more motivation to improve my circuit analysis skills, [b]for absolute beginners however it may be rather difficult to keep up.[/b]
[/QUOTE]

I found it really difficult, I was hoping I would be able to get more out of the first few lectures than I did. Then again, I haven't taken any of the prerequisite courses yet, (Well, currently taking physics but we haven't gotten to electricity yet) so I guess I'll just stick with online guides/resources for now

[Implosive]

[QUOTE=ruarai;35018546]I found a nifty chart to decode resistors from this guys site
[url]http://worrydream.com/#!/ResistorDecoder[/url]
[img]http://worrydream.com/ResistorDecoder/resistors.png[/img][/QUOTE]

What if you're colorblind? :(

[Chipset]

[QUOTE=SteelReal;35044110]What if you're colorblind? :([/QUOTE]

Multimeter.

[Lapsus]

[QUOTE=SteelReal;35044110]What if you're colorblind? :([/QUOTE]

Somene made an iphone app for that, no idea if there's an android version though. [url]http://nothinglabs.blogspot.com/2011/11/resistor-photo-id.html[/url]

[Lapsus]

[table][tr][td][img]http://imgkk.com/i/yb3e.jpg[/img][/td][td][img]http://imgkk.com/i/ctve.jpg[/img][/td][/tr][/table]

Finally got something done with the buttons, just a simple game controller, the arduino handles debouncing and assembling the packet to be sent to the 8u2, which is running [url=http://hunt.net.nz/users/darran/weblog/b3029/Arduino_UNO_Keyboard_HID_version_03.html] a firmware that makes it identify as a usb keyboard[/url], basically a mashup of the default Arduino usbserial firmware and the LUFA USB keyboard example code.

// Pins
int buttonpin[9] = {2,3,4,5,6,7,8,9,10};
int led = 13;

// Variables
uint8_t buffer[8] = {0,0,0,0,0,0,0,0}; // This is the packet for the lufa+serial mashup running on the 8u2
unsigned long time = 0;                // Byte zero is modifier keys, 1 is unused, 2-7 are keys being held
int temp = 0;                          // The state of the button currently being read.
int button[9] = {0,0,0,0,0,0,0,0,0};   // The state of all the buttons.
unsigned long lastChange[9] = {0,0,0,0,0,0,0,0,0}; // When the buttons last changed, to debounce
int numDown = 0;                       // How many buttons are currently down
int lastDown = 3;                      // How many buttons were down last time through the loop
int counter = 0;                       // For constructing the packet
int debounce = 10;                     // How long to ignore button changes in milliseconds

void setup()
{
  Serial.begin(9600);         // Serial, yay.
  
  pinMode(led, OUTPUT);       // Gotta have blinky lights.
  
  for (int i = 0; i < 9; i++) // Set up pins, blink lights, etc
  {                           // The delay also gives the 8u2 time to do its thing
    digitalWrite(led, HIGH);
    pinMode(buttonpin[i], INPUT);
    digitalWrite(buttonpin[i], HIGH); // internal pull-up resistors are just the best
    delay(20);
    digitalWrite(led, LOW);
    delay(20);
  }
}

void loop()
{
  time = millis();
  
  for (int i = 0; i < 9; i++)
  {
    temp = !digitalRead(buttonpin[i]); // Buttons are active low, so invert the reading
    
    if ((button[i] == 0) && (temp == 1) && (lastChange[i] + debounce < time))
    {  // If the button been pressed, and the debounce time has expired
      lastChange[i] = time;
      button[i] = temp;
      numDown += 1;
    } 
    else if ((button[i] == 1) && (temp == 0) && (lastChange[i] + 10 < time))
    {  // If the button been released, and the debounce time has expired
      lastChange[i] = time;
      button[i] = temp;
      numDown -= 1;
    }
  }
  
  if (!(numDown == lastDown))
  {  // Something's changed
    digitalWrite(led, HIGH); // make the light blink
    
    for (int i = 0; i < 8; i++)
    {
      buffer[i] = 0; // empty the buffer
    }
    
    counter = 2; // make sure not to put garbage in the modifier keys
    
    for (int i = 0; i < 9; i++) // and build a packet!
    {
      if (button[i] == 1)
      {
        if (counter < 8) // if we're not out of space. I think we'll be fine with 6 max for now
        {
          buffer[counter] = i + 4; // +4 makes it start a a, so we get a-i as outputs
          counter++;
        }
      }
    }
    Serial.write(buffer, 8); // Send the packet
    digitalWrite(led, LOW);  // turn off the LED
    lastDown = numDown;      // update the change tracking thing
  }
  
}

[DrLuke]

looks pretty cool

[Goz3rr]

I'm in need of some help with switches and an arduino actually. It's a DPTP switch, with 6 pins on the bottom (two positions for the switch, i'm guessing two separate channels). So to make this work properly with an arduino, I should apply 5V to the center pin, then wire the top or bottom pin to a digital pin on the arduino and a 10k resistor to the GND right?

[Lapsus]

Assuming you mean DPDT, which is likely because of the 6 pins, the easiest way to wire it up would be to connect the centre of the switch to ground, and the pin to the left or the right of it to whichever pin you want to connect it to.
From there, when you're setting up your pins in the code, after you set the pin as an input, use digitalwrite to set the pin high, and it'll activate an internal pull-up resistor, meaning when the switch is open, reading that pin will give you a 1, and when it's closed, it'll read 0.

Looking at the switch from the bottom, each period being a pin, you'd wire it like this.

+-------+
| . . . |
| . . . |
+-|-|---+
  | |
  | +-- Ground
  +---- Arduino pin

And in your code,

void setup()
{
  pinMode(yourpin, INPUT);
  digitalWrite(yourpin, HIGH);
}