This is a project of binary watch which is able to show time, date and its battery level. Three side LEDs show what is currently on display. The watch is based on an ATMega328p and a PCF8563 real-time clock. All control is done using one press bottom. Light-sensing is implemented for brightness adjustments.
The repository contains a first prototype of the watch to be implemented in a wooden hand watch. Both source code, board design files are included. The first prototype has been implemented on a breadboard and is fully functional. The second prototype was build in a wooden wrist watch and is fully functional.
- 25 LEDs
- ATMega328p microcontroller
- PCF8563 real-time clock
- Small tactile switch
- MCP73831T Li-Ion battery charger
- Rechargeable 2032 Li-Ion battery
- Phototransistor for LED intensity adjustment
- USB connector for charging
The main part of the project is based on an 8-bit microcontroller (uC) ATMega328p connected to the PCF8563 real-time clock (RTC) using I2C. The RTC keeps the correct time, whereas the uC is responsible for all logical operations, inputs from the button and LED output. When the button is pressed, the uC wakes up and the current time is read from the RTC. The time (hours, minutes, seconds) is displayed in a binary-coded decimal (BCD) format on the LEDs using multiplexing. If the button is pressed shortly once more, date (day, month, year) is displayed. Third short press shows the battery voltage. Another short press puts the uC to the sleep mode again. If the button is not pressed for more than 8 s, the uC goes to the sleep mode and all LED are turned off. If a longer press is performed, the watch goes into the sleep mode from either of the previous states.
To enter the time-setting mode, the button has to be pressed for more than 1 s in either of the previously mentioned modes. If the time-setting mode is entered, a variable to be set starts to blink (first, variable second starts to blink). A short press increments the corresponding variable, longer press (over 0.25s) moves to the next variable (seconds -> minutes -> hours -> day -> month -> year), extra long press confirms the changes and makes the watch to return to the time-display mode.
To save the energy during the run-time and minimize the parts-count, the uC runs on an internal 1 MHz oscillator.
Note: As included, the code is working though it is still under development and far from being optimal.
The watch is programmed in C++ and is split into three different parts. For the communication with the RTC, twi.h and twi.cpp files were created. For the basic watch operation (button press, LED multiplexing, time reading/setting) a watch.h and watch.cpp files were created. The main.cpp then binds everything together.
The board is designe using EAGLE and its lates version (9.5.1). The file Top_final shows a look of the watch, the files Top_copper and Bot_copper show the board design. Files BinaryWatch_v0_4_OptR_fix are the EAGLE files.
- Improve the coding and commenting
- Making a more versatile design which can be used in different watches ranging from tiny hand watches to table/wall watches.
- Implement USB communication with PC to be able to conveniently set up time on the watch (different uC needed).
