TinyPomodoro — Pomodoro Timer, Clock & Date Display
How it works
- 3-mode timer and clock system driven by 50MHz clock
- Displays output on external MAX7219 8-digit 7-segment display via SPI
- 4 breadboard buttons for input
Modes
The design has three display modes, cycled with btn_right:
| LED[1:0] |
Mode |
Display format |
00 |
CLOCK |
HH MM SS -- |
01 |
DATE |
DD - MM - -- -- |
10 |
POMODORO |
-- -- MM SS -- -- |
Clock / Counter Chain
- 50 MHz clock feeds a clock divider that produces a 1 Hz tick
- Counter chain tracks seconds (0-59), minutes (0–59), hours (0–23), days (1–31), and months (1–12)
- Each counter (except seconds) has a write-enable so each field can be incremented/decremented
FSM & Mode Control
main_mode_fsm top-level display mode (CLOCK, DATE, POMODORO) and a setup sub-mode for each. Pressing btn_left enters setup for the current mode; pressing it again exits setup and saves the values.
setup_field_fsm controls which field is being edited during setup. In clock setup, btn_right cycles between minutes and hours. In date setup, it cycles between day and month. The currently selected field blinks like a cursor!
pomodoro_fsm implements Pomodoro timer with four states: IDLE, WORK, BREAK, and ALARM. In POMODORO mode, btn_up starts or pauses the countdown and btn_down resets it. The timer defaults to 25-minute work sessions and 5-minute breaks. When a session expires the design enters ALARM state and asserts buzzer_en before returning to IDLE.
SPI Display Driver
- SPI drivers sends 16-bit frames to MAX7219 chip
- Based on logic from max7219TinyFPGA
- Binary counter values are converted to BCD using lookup-tables rather than dividers
Button Routing
- Active high buttons with external 10kΩ pull-down resistors
- 4 buttons are debounced and converted to rising-edge signals
| Button |
Outside setup |
Inside setup |
btn_left |
Enter setup |
Exit setup and save |
btn_right |
Cycle mode |
Cycle to next field |
btn_up |
Start/pause pomodoro |
Increment selected field |
btn_down |
Reset pomodoro |
Decrement selected field |
How to test
Setup
- Connect the MAX7219 8-digit display module to the
uio pins
- Connect four push buttons between the
ui input pins and VCC, with 10kΩ pull-down
resistors to GND on each button pin
- Power on. Display should show
00 00 00 -- (hours, minutes, seconds, blank) in
CLOCK mode
Testing clock mode
- Seconds should increment on rightmost two digits every second
- Press
btn_left — LED[2] should turn on and the minute digits should start blinking
- Press
btn_up — minutes should increment
- Press
btn_right — the hour digits blink
- Press
btn_up / btn_down to change hours
- Press
btn_left — LED[2] turns off, setup exits, clock resumes counting
Testing date mode
- Press
btn_right once — LED[1:0] shows 01, display shows DD - MM - -- --
- Press
btn_left to enter setup — day digits blink
- Press
btn_up / btn_down to change the day
- Press
btn_right to cycle to month — month digits blink
- Press
btn_up / btn_down to change the month
- Press
btn_left to exit setup
Testing pomodoro mode
- Press
btn_right twice from CLOCK mode — LED[1:0] shows 10
- Display shows
-- 25 00 --
- Press
btn_up to start the countdown — LED[3] (led_work) turns on
- Press
btn_up again to pause
- Press
btn_down to reset back to 25:00
- When the countdown reaches 00:00 the design enters ALARM state — LED[5] (buzzer_en), then automatically transitions to BREAK (5:00 countdown, LED[4] turns on)
LED indicators
| LED |
Meaning |
| LED[1:0] |
Current mode: 00=CLOCK, 01=DATE, 10=POMODORO |
| LED[2] |
Setup mode active |
| LED[3] |
Pomodoro work phase running |
| LED[4] |
Pomodoro break phase running |
| LED[5] |
Pomodoro alarm active |
| LED[7:6] |
Setup field selected: 00=MIN, 01=HOUR, 10=DAY, 11=MON |
External hardware
MAX7219 8-digit 7-segment LED display
Wiring:
| MAX7219 pin |
TinyTapeout pin |
Description |
| VCC |
3.3V |
Power |
| GND |
GND |
Ground |
| DIN |
uio[0] |
SPI data |
| CS/LOAD |
uio[1] |
SPI chip select (active low) |
| CLK |
uio[2] |
SPI clock |
Push buttons (×4)
| Button |
ui pin |
Function |
| btn_left |
ui[0] |
Enter/exit setup |
| btn_right |
ui[1] |
Cycle mode / cycle field |
| btn_up |
ui[2] |
Increment / start pomodoro |
| btn_down |
ui[3] |
Decrement / reset pomodoro |
