WS2812 LED Binary Clock Project Documentation

Hardware Description

Schematics

The schematic was created in KiCad. It includes:

ATmega164A microcontroller: Acts as the main controller of the binary clock system.
WS2812 LEDs: A series of 24 individually addressable LEDs arranged in logical time display groups. These are controlled via a single data line connected to pin PB1 (PORTB.1).
Input buttons: Four push-buttons connected to PB3, PB6, PB7, and PD5 are used to toggle modes and increment hours, minutes, and seconds during setup.
Resistors: Several 330Ω resistors are placed in series with the buttons as current limiting or pull-down/up resistors.
X1 – 16 MHz Crystal Oscillator: Provides the clock signal for the microcontroller's system timing. Ensures accurate timing for WS2812 data transmission.
C1 and C2 – 22pF Capacitors: Connected to the crystal oscillator (X1), they stabilize the oscillator circuit and ensure proper startup and frequency stability of the crystal.
C3 – 100nF Decoupling Capacitor: Placed close to the ATmega164A's VCC and GND pins to filter out voltage spikes and provide a stable power supply for the microcontroller.

Bill of Materials

Cantitate	Ref	Valoare	Capsulă	Furnizor, cod produs	Preț unitar (lei)
24	D1-D24	LED BAND	THT	UPB
4	R1,R2,R3,R4	330Ohm	THT	ardushop.ro, CJADNL_CR1/4W-330R-5pc-ST26	0.27 RON
2	C1,C2	22pF	SMD	UPB
1	U1	ATMega16A	DIP40	UPB
1	C3	100pF	THT	UPB
1	X1	Crystal	THT	UPB

Additional Hardware Features

The project uses WS2812 LED strips for visual time display, controlled via a single data line on PB1. Four push-buttons connected to PB3, PB6, PB7, and PD5 allow user interaction for setup and time adjustment:

PB7: Toggle between normal and setup mode.
PB3: Increment hour in setup mode.
PB6: Increment minute in setup mode.
PD5: Increment second in setup mode.

Software Description

Overview

Firmware was developed for the ATmega164A microcontroller running at 20 MHz using CVAVR compiler. The main functions include displaying time on WS2812 LEDs in binary-coded decimal, supporting setup mode for time adjustment via buttons, and using blinking LEDs to indicate system state.

Software Logic

The main loop polls buttons to detect mode toggling and increments time units when in setup mode. Time is displayed by sending color data representing each binary digit of HH:MM:SS to the WS2812 LED strip. The system wraps time values appropriately and provides visual feedback using red LEDs for bits set and blinking green LEDs for status.

Results and Conclusions

The project successfully implements a binary clock displayed on WS2812 LEDs. Time can be set intuitively with push-buttons using hold-to-increment functionality. Visual feedback distinguishes normal mode (blinking green LEDs) from setup mode (solid green LEDs). Precise timing for WS2812 communication was accomplished using assembly NOP instructions.