chess timer (***In progress)

 
 

proof of concept

A quick Arduino proof of concept was made to test the buttons under different modes of operation experienced in a typical Chess match (e.g. rapid presses). Each player presses his/her corresponding button to signal the end of a turn. One button illuminates at a time to indicate which player’s turn it is.

 
Proof-of-Concept-Setup-Resized.jpg
 
 
 

Hardware

A full schematic and PCB was then created to implement the following additional features:

  1. ARM microcontroller:

    • Real-time clock to track each player’s remaining time.

    • ADC to monitor battery level and detect touchscreen presses.

    • Analog Watchdog that turns off the device when the battery falls below 3.0V.

    • SWD programming.

    • Power and GPIO breakouts for prototyping.

  2. Power Management System (LiPo Battery):

    • LiPo battery safety (overvoltage, undervoltage, overdischarge, and short circuit protection). Included in purchased LiPo.

    • LiPo charging through USB (constant current, constant voltage charging).

    • Appropriate power distribution (USB powered when charging, battery powered otherwise).

    • Charging status indication (through LED or host microcontroller).

    • 3.3V output from the buck-boost converter when the LiPo battery is between 2.7V - 4.2V.

  3. User Interface:

    • Touchscreen GUI.

    • Player Buttons. Input to PWM for brightness control.

SCHEMATIC

PCB

PCB characteristics:

  • 4 layers (Signal - GND - 3.3V - Signal).

  • 74mm x 70mm (2.9in x 2.75in).

  • Test points to verify charging IC and buck-boost regulator functionality before connecting a LiPo to the circuit (TP1 - TP8).

  • 4x enclosure mounting holes (M3 screws). 3 additional holes to further stabilize PCB to enclosure.

  • 4x display mounting holes.

  • Manufacturer = JLCPCB.

Full Board Layout

Layer Stackup

Top Layer

GND Layer

3.3V Layer

Bottom Layer

Manufactured PCB (74mm x 70mm)

Display Mounting: Flex cable soldered directly to footprint. Adhesive tape and mounting pegs on display further stabilize it to the PCB

rev a. - firmware

GitHub Repo: https://github.com/ress059/Chess-Timer

Firmware currently in progress. Currently prototyping UI using Windows Simulator with LVGL library; the library is structured so this code can easily be ported to a host microcontroller once simulator prototyping is complete. Relevant source files are main.c and the chess_timer_ui folder. The current plan is to use bare-metal with low-priority interrupts calling lv_tick_inc() and lv_task_handler() to drive the display.