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Home Brew Watch

With Apple recently announcing their horrible smart watch, I thought it's only fair if hardware hobbyists also get the chance to build their own. Obviously being a student at current it can't be too expensive. Where possible, I have cut corners to the extreme to try and make sure I don't break the bank with this little experiment and more importantly so that others can do it too.

I'll aim to add to this project when I learn more about what I'm actually doing and as with all of this, when I get spare time!

Parts List

The following parts were used in the construction of this device:

Main Controller

Picture of Digispark

Picture of Digispark

Image from Digistump.com, the official location for Digispark.

I wanted to make sure it was quick to get up and running with this project without having to deal with more hardware based issues I was already going to have to contend with. For this, it made sense to use an Arduino based project as experience with these in the past has always been great!

After working in the industry for a while, I decided the Digispark was nice and under powered for what I needed - so that would do the trick! The Digispark has a nice little Atmel Attiny85 MCU, which although fast offers only a small 6KB of programming space after the bootloader. If this wasn't enough, I bought a Nokia 5110 screen, with 8 pins on it including VCC and GND, which would be okay if the Digispark had 6 pins where 2 of them weren't for USB! A challenge...

Pin Out

TODO: Pin out to be updated soon...

Code

This is the code I have so far, it's a work in progress as everything is but it should work reasonably well... As you can probably tell, it doesn't actually do it's job yet!

/*
Scrolling text example code
Modified from: http://www.arduino.cc/playground/Code/PCD8544
*/

// The pins to use on the arduino
#define PIN_BACK  4
#define PIN_RESET 5//6
#define PIN_DC    2//5
#define PIN_SDIN  1//4
#define PIN_SCLK  0//3

// Configuration for the LCD
#define LCD_C     LOW
#define LCD_D     HIGH
#define LCD_CMD   0

// Size of the LCD
#define LCD_X     84
#define LCD_Y     48

int scrollPosition = -10;

static const byte ASCII[][5] =
{
 {0x00, 0x00, 0x00, 0x00, 0x00} // 20
,{0x00, 0x00, 0x5f, 0x00, 0x00} // 21 !
,{0x00, 0x07, 0x00, 0x07, 0x00} // 22 "
,{0x14, 0x7f, 0x14, 0x7f, 0x14} // 23 #
,{0x24, 0x2a, 0x7f, 0x2a, 0x12} // 24 $
,{0x23, 0x13, 0x08, 0x64, 0x62} // 25 %
,{0x36, 0x49, 0x55, 0x22, 0x50} // 26 &
,{0x00, 0x05, 0x03, 0x00, 0x00} // 27 '
,{0x00, 0x1c, 0x22, 0x41, 0x00} // 28 (
,{0x00, 0x41, 0x22, 0x1c, 0x00} // 29 )
,{0x14, 0x08, 0x3e, 0x08, 0x14} // 2a *
,{0x08, 0x08, 0x3e, 0x08, 0x08} // 2b +
,{0x00, 0x50, 0x30, 0x00, 0x00} // 2c ,
,{0x08, 0x08, 0x08, 0x08, 0x08} // 2d -
,{0x00, 0x60, 0x60, 0x00, 0x00} // 2e .
,{0x20, 0x10, 0x08, 0x04, 0x02} // 2f /
,{0x3e, 0x51, 0x49, 0x45, 0x3e} // 30 0
,{0x00, 0x42, 0x7f, 0x40, 0x00} // 31 1
,{0x42, 0x61, 0x51, 0x49, 0x46} // 32 2
,{0x21, 0x41, 0x45, 0x4b, 0x31} // 33 3
,{0x18, 0x14, 0x12, 0x7f, 0x10} // 34 4
,{0x27, 0x45, 0x45, 0x45, 0x39} // 35 5
,{0x3c, 0x4a, 0x49, 0x49, 0x30} // 36 6
,{0x01, 0x71, 0x09, 0x05, 0x03} // 37 7
,{0x36, 0x49, 0x49, 0x49, 0x36} // 38 8
,{0x06, 0x49, 0x49, 0x29, 0x1e} // 39 9
,{0x00, 0x36, 0x36, 0x00, 0x00} // 3a :
,{0x00, 0x56, 0x36, 0x00, 0x00} // 3b ;
,{0x08, 0x14, 0x22, 0x41, 0x00} // 3c <
,{0x14, 0x14, 0x14, 0x14, 0x14} // 3d =
,{0x00, 0x41, 0x22, 0x14, 0x08} // 3e >
,{0x02, 0x01, 0x51, 0x09, 0x06} // 3f ?
,{0x32, 0x49, 0x79, 0x41, 0x3e} // 40 @
,{0x7e, 0x11, 0x11, 0x11, 0x7e} // 41 A
,{0x7f, 0x49, 0x49, 0x49, 0x36} // 42 B
,{0x3e, 0x41, 0x41, 0x41, 0x22} // 43 C
,{0x7f, 0x41, 0x41, 0x22, 0x1c} // 44 D
,{0x7f, 0x49, 0x49, 0x49, 0x41} // 45 E
,{0x7f, 0x09, 0x09, 0x09, 0x01} // 46 F
,{0x3e, 0x41, 0x49, 0x49, 0x7a} // 47 G
,{0x7f, 0x08, 0x08, 0x08, 0x7f} // 48 H
,{0x00, 0x41, 0x7f, 0x41, 0x00} // 49 I
,{0x20, 0x40, 0x41, 0x3f, 0x01} // 4a J
,{0x7f, 0x08, 0x14, 0x22, 0x41} // 4b K
,{0x7f, 0x40, 0x40, 0x40, 0x40} // 4c L
,{0x7f, 0x02, 0x0c, 0x02, 0x7f} // 4d M
,{0x7f, 0x04, 0x08, 0x10, 0x7f} // 4e N
,{0x3e, 0x41, 0x41, 0x41, 0x3e} // 4f O
,{0x7f, 0x09, 0x09, 0x09, 0x06} // 50 P
,{0x3e, 0x41, 0x51, 0x21, 0x5e} // 51 Q
,{0x7f, 0x09, 0x19, 0x29, 0x46} // 52 R
,{0x46, 0x49, 0x49, 0x49, 0x31} // 53 S
,{0x01, 0x01, 0x7f, 0x01, 0x01} // 54 T
,{0x3f, 0x40, 0x40, 0x40, 0x3f} // 55 U
,{0x1f, 0x20, 0x40, 0x20, 0x1f} // 56 V
,{0x3f, 0x40, 0x38, 0x40, 0x3f} // 57 W
,{0x63, 0x14, 0x08, 0x14, 0x63} // 58 X
,{0x07, 0x08, 0x70, 0x08, 0x07} // 59 Y
,{0x61, 0x51, 0x49, 0x45, 0x43} // 5a Z
,{0x00, 0x7f, 0x41, 0x41, 0x00} // 5b [
,{0x02, 0x04, 0x08, 0x10, 0x20} // 5c ¥
,{0x00, 0x41, 0x41, 0x7f, 0x00} // 5d ]
,{0x04, 0x02, 0x01, 0x02, 0x04} // 5e ^
,{0x40, 0x40, 0x40, 0x40, 0x40} // 5f _
,{0x00, 0x01, 0x02, 0x04, 0x00} // 60 `
,{0x20, 0x54, 0x54, 0x54, 0x78} // 61 a
,{0x7f, 0x48, 0x44, 0x44, 0x38} // 62 b
,{0x38, 0x44, 0x44, 0x44, 0x20} // 63 c
,{0x38, 0x44, 0x44, 0x48, 0x7f} // 64 d
,{0x38, 0x54, 0x54, 0x54, 0x18} // 65 e
,{0x08, 0x7e, 0x09, 0x01, 0x02} // 66 f
,{0x0c, 0x52, 0x52, 0x52, 0x3e} // 67 g
,{0x7f, 0x08, 0x04, 0x04, 0x78} // 68 h
,{0x00, 0x44, 0x7d, 0x40, 0x00} // 69 i
,{0x20, 0x40, 0x44, 0x3d, 0x00} // 6a j
,{0x7f, 0x10, 0x28, 0x44, 0x00} // 6b k
,{0x00, 0x41, 0x7f, 0x40, 0x00} // 6c l
,{0x7c, 0x04, 0x18, 0x04, 0x78} // 6d m
,{0x7c, 0x08, 0x04, 0x04, 0x78} // 6e n
,{0x38, 0x44, 0x44, 0x44, 0x38} // 6f o
,{0x7c, 0x14, 0x14, 0x14, 0x08} // 70 p
,{0x08, 0x14, 0x14, 0x18, 0x7c} // 71 q
,{0x7c, 0x08, 0x04, 0x04, 0x08} // 72 r
,{0x48, 0x54, 0x54, 0x54, 0x20} // 73 s
,{0x04, 0x3f, 0x44, 0x40, 0x20} // 74 t
,{0x3c, 0x40, 0x40, 0x20, 0x7c} // 75 u
,{0x1c, 0x20, 0x40, 0x20, 0x1c} // 76 v
,{0x3c, 0x40, 0x30, 0x40, 0x3c} // 77 w
,{0x44, 0x28, 0x10, 0x28, 0x44} // 78 x
,{0x0c, 0x50, 0x50, 0x50, 0x3c} // 79 y
,{0x44, 0x64, 0x54, 0x4c, 0x44} // 7a z
,{0x00, 0x08, 0x36, 0x41, 0x00} // 7b {
,{0x00, 0x00, 0x7f, 0x00, 0x00} // 7c |
,{0x00, 0x41, 0x36, 0x08, 0x00} // 7d }
,{0x10, 0x08, 0x08, 0x10, 0x08} // 7e ←
,{0x00, 0x06, 0x09, 0x09, 0x06} // 7f →
};

void LcdCharacter(char character){
  LcdWrite(LCD_D, 0x00);
  for(int index = 0; index < 5; index++)
    LcdWrite(LCD_D, ASCII[character - 0x20][index]);
  LcdWrite(LCD_D, 0x00);
}

void LcdClear(void){
  for(int index = 0; index &lt; LCD_X * LCD_Y / 8; index++)
    LcdWrite(LCD_D, 0x00);
}

void LcdInitialise(void){
  pinMode(PIN_BACK,  OUTPUT);
  pinMode(PIN_RESET, OUTPUT);
  pinMode(PIN_DC,    OUTPUT);
  pinMode(PIN_SDIN,  OUTPUT);
  pinMode(PIN_SCLK,  OUTPUT);
  
  digitalWrite(PIN_RESET, LOW);
  digitalWrite(PIN_RESET, HIGH);
  
  LcdWrite(LCD_CMD, 0x21);  // LCD Extended Commands.
  LcdWrite(LCD_CMD, 0x98);  // Set LCD Vop (Contrast). //B1
  LcdWrite(LCD_CMD, 0x04);  // Set Temp coefficent. //0x04
  LcdWrite(LCD_CMD, 0x14);  // LCD bias mode 1:48. //0x13
  LcdWrite(LCD_CMD, 0x0C);  // LCD in normal mode. 0x0d for inverse
  LcdWrite(LCD_C, 0x20);
  LcdWrite(LCD_C, 0x0C);
}

void LcdString(char *characters){
  while (*characters){
    LcdCharacter(*characters++);
  }
}

void LcdWrite(byte dc, byte data){
  digitalWrite(PIN_DC, dc);
  shiftOut(PIN_SDIN, PIN_SCLK, MSBFIRST, data);
}

/**
 * gotoXY routine to position cursor
 * x - range: 0 to 84
 * y - range: 0 to 5
 **/
void gotoXY(int x, int y){
  LcdWrite( 0, 0x80 | x);  // Column.
  LcdWrite( 0, 0x40 | y);  // Row.
}

void drawBox(void){
  int j;
  for(j = 0; j &lt; 84; j++){ // top
    gotoXY(j, 0);
    LcdWrite(1, 0x01);
  }
  
  for(j = 0; j &lt; 84; j++){ //Bottom
    gotoXY(j, 5);
    LcdWrite(1, 0x80);
  }
  
  for(j = 0; j &lt; 6; j++){ // Right
    gotoXY(83, j);
    LcdWrite(1, 0xff);
  }
  
  for(j = 0; j &lt; 6; j++){ // Left
    gotoXY(0, j);
    LcdWrite(1, 0xff);
  }
}

void setup(void){
  LcdInitialise();
  LcdClear();
  drawBox();
  
  gotoXY(5,1);
  LcdString("><><><><><><");
  gotoXY(5,2);
  LcdString("B[]Arrayx");;
}

void loop(void){
  gotoXY(5,3);
  int mins = millis() / 1000;
  String val = String(mins);
  val += "\0";
  char buffer[10];
  val.toCharArray(buffer, 10u);
  LcdString(buffer);
  digitalWrite(PIN_BACK, HIGH);
  delay(250);
}