PREAMBLE

AWATCH is a simple watch that shows the time on an OLED display and can be operated with one button only. It shows hours, minutes, seconds, day and battery voltage.
To save power AWATCH uses the watchdog timer of AVR microcontrollers. So the display remains dark and the microcontroller in sleep mode until the button ist pressed. Longpressing the button alters the setting state, while shortpressing alters the setable value.

Have fun
deetee

OPERATION

AWATCH uses an OLED display (64x48 I2C SSD1306) and because of the size of less then 4 Kilobytes it can be compiled for many Arduino/AVR microcontrollers (i.e. ATTINY or Digispark).

Setting Modes (alter with longpressing the button):

• 0 ... Show time, no setting
• 1 ... Reset seconds
• 2 ... Add one minute
• 3 ... Add 10 minutes
• 4 ... Add one hour
• 5 ... Add 10 hours
• 6 ... Add one day

Note: After the timeout of 5s AWATCH enters the sleep mode and resets the setting mode.

Tweaking:

• Define the brightness of the display (0...255) with: #define CONTRAST 0x80
• Define the timeout (in ms) with: #define TIMEOUT 5000
• Set 12/24h-format with: #define TIME1224 24UL // 12 or 24 hours
• Calibrate watchdog intervall time (ms) with: static unsigned int wdtmillisperinterrupt = 1072;

CIRCUIT DIAGRAM

 _________________
|   OLED-DISPLAY  |
|  64x48 SSD1306  |
|_GND_VCC_SCK_SDA_|
   |   |   |   |
           |   |
 __|___|___|___|__
| GND VCC P2  P0  |
|  AVR  ATTINY85  |
|_P3______________|
   |   
   / Set button   
   |
  GND