CARDPUTER StudyTimer

A calm, low-friction study timer for the M5Stack Cardputer.

The timer is the primary feature. Logging is a passive side effect. The intended daily flow is:

Power on
Previous timer appears
Press Enter
Start studying

Concept

CARDPUTER StudyTimer is designed to feel closer to a simple 100-yen shop timer than a productivity app.

It is intentionally standalone:

• Cardputer only
• No extra UNIT modules
• No MQTT
• No Home Assistant
• No cloud features
• No gamification
• No subject-name input

Wi-Fi and NTP are optional background helpers. The timer remains usable even if Wi-Fi, NTP, or SD logging fails.

Features

• Fast startup with the previous timer value shown immediately
• Presets: 5, 10, 15, 25, and 45 minutes
• Manual minute input from 1 to 99 minutes
• Large remaining-time display
• Four-edge segmented progress display
• Japanese and English UI
• Sound modes: Quiet, Normal, Loud
• Low-battery visual warning at 20% or less when not charging
• Passive CSV logging to microSD
• Background Wi-Fi/NTP time sync
• No startup wait for Wi-Fi or NTP

Controls

Ready

• Enter: start the previous timer
• 1 to 5: start a preset
• 0: enter a custom minute value
• S: open settings
• L: open stats in Rich mode
• V: open voice memos in Rich mode
• Hold M: record a voice memo from any screen in Rich mode

Custom Input

• Number keys: enter minutes
• Enter: start
• Del: delete one digit, or return to Ready when empty

Running / Paused

• Enter: pause or resume
• Del: open reset confirmation

Settings

Press S to open Language, then use fn + / and fn + , to switch between Language, Volume, and Mode in page order.

Language:

• 1: Japanese
• 2: English

Volume:

• 1: Quiet
• 2: Normal
• 3: Loud

Mode:

• 1: Simple, timer and settings only
• 2: Rich, stats and voice memos enabled

The default mode is Simple. CSV logging and time sync continue in the background even in Simple mode.

Controls:

• fn + ,: previous settings page
• fn + ;: move selection up
• fn + .: move selection down
• fn + /: next settings page
• Enter: apply selected item
• Del: return to Ready

Stats

In Rich mode, press L to show stats from study_log.csv on the SD card.

• today's total
• last 7 days total
• streak days
• simple 7-day bars

Synced devices use the exact NTP date. Before NTP sync, stats can still use a saved date as OFFLINE DATE when a previous sync exists. Stats still require an available SD card.

Voice Memos

In Rich mode, hold M to record a voice memo from the built-in microphone. Recording does not stop the timer. Voice memos are saved as WAV files under /voice_memos/ on the SD card.

• Hold M: record
• Release M: save
• V: open voice memo list
• fn + ;: previous memo
• fn + /: next memo
• Enter: play or stop
• Del: return

Synced devices use timestamp filenames. Unsynced devices use sequential filenames.

Configuration

Copy config.example.h to config.h and edit only config.h.

#define WIFI_ENABLED true
#define WIFI_SSID ""
#define WIFI_PASSWORD ""

#define NTP_SERVER_1 "pool.ntp.org"
#define NTP_SERVER_2 "time.google.com"
#define NTP_SERVER_3 "time.cloudflare.com"
#define GMT_OFFSET_SECONDS 32400
#define DAYLIGHT_OFFSET_SECONDS 0

Do not commit real Wi-Fi credentials. config.h is intentionally ignored.

If Wi-Fi is not configured, the timer still works. When a previous sync date is available, completed sessions are logged as offline with a date. If no date is available, they are logged as unsynced.

CSV Log

Completed sessions are appended to:

/study_log.csv

Current CSV format:

date,time,sync_status,duration_min,completed,input_type
2026-05-19,13:32:52,synced,25,1,preset4
2026-05-19,14:10:12,synced,45,1,custom
2026-05-19,,offline,25,1,preset4
,,unsynced,15,1,preset3

Columns:

• date: YYYY-MM-DD, empty when no date is available
• time: HH:MM:SS, empty when NTP is not synced
• sync_status: synced, offline, or unsynced
• duration_min: timer duration in minutes
• completed: 1 for completed sessions
• input_type: preset1 to preset5, or custom

The date and time columns are split so the Cardputer can later aggregate daily totals locally without parsing a combined timestamp string.

Build

Target board:

m5stack:esp32:m5stack_cardputer

Required Arduino libraries include:

• M5Cardputer
• M5Unified
• M5GFX

Example compile command:

arduino-cli compile --fqbn m5stack:esp32:m5stack_cardputer .

Repository Contents

This public-ready repository intentionally tracks only:

• CARDPUTER-StudyTimer.ino
• README.md
• README.ja.md
• LICENSE
• config.example.h
• images/
• .gitignore

Local notes, generated docs, private configuration, and editor files are ignored.

AI Assistance

This project was developed with assistance from AI tools, including Codex app and GitHub Copilot.

License

This project is licensed under the MIT License.

Copyright (c) 2026 omiya-bonsai