EPaperClock

ESP32 firmware (Arduino IDE / arduino-cli) for a 1.54" e-paper clock. Shows a 24h digital clock (NTP, configured timezone).

Status: the panel is wired and driven by a hello-world sketch — a full-screen partial refresh on every 1 min wake, over deep sleep, with no flashing. The clock layout below isn't drawn yet.

Display layout

Normal	Fallback

Element	Content	Example	Fallback
Time	24h HH:MM, the largest element	14:37	--:--
Temperature	current temp in °C, next to the weather icon	18°C	--°C
Date	weekday + dd/mm	QUA 22/07	--- --/--

Each area degrades on its own: weather when OpenWeather fails, time and date only on a never-synced board (no NTP, no RTC), rather than showing a plausible wrong time. The mockup uses Bebas Neue; on-device that maps to a bitmap/GFX big font.

Hardware

Waveshare 1.54" e-Paper (V2) — 200×200 monochrome SSD1681, partial refresh — on a LOLIN C3 Pico (ESP32-C3), wired to the FSPI bus.

E-paper	Function	LOLIN C3 Pico	Wire color
VCC	3.3V power	3V3	${\color{#808080}\textsf{Gray}}$
GND	Ground	GND	${\color{#8B4513}\textsf{Brown}}$
DIN	MOSI (SPI data)	IO6	${\color{#1E6FD9}\textsf{Blue}}$
CLK	SCK (SPI clock)	IO4	${\color{#D4A800}\textsf{Yellow}}$
CS	Chip Select	IO3	${\color{#E8730C}\textsf{Orange}}$
DC	Data / Command	IO2	${\color{#2E9E44}\textsf{Green}}$
RST	Reset	IO1	${\color{#BDBDBD}\textsf{White}}$
BUSY	Busy status	IO0	${\color{#7B3FA0}\textsf{Purple}}$

• LOLIN C3 Pico pinout
• Waveshare 1.54" e-Paper — ESP32 wiring

Build, Upload

Board: LOLIN C3 Pico (esp32:esp32:lolin_c3_pico), pinned in sketch.yaml.

arduino-cli compile --upload --profile lolin_c3_pico -p /dev/ttyACM0 .
arduino-cli monitor --profile lolin_c3_pico -p /dev/ttyACM0
./scripts/upload-littlefs.sh   # flashes data/config.json

PORT/CHIP/BAUD/PARTITION_OFFSET/PARTITION_SIZE are overridable env vars on upload-littlefs.sh. No test suite — a clean compile/upload is the definition of done.

TODO

1. Migrate all code to ESP32.
2. Move to the LOLIN C3 Pico (ESP32-C3): board, e-paper pinout, FSPI.
3. Deep sleep with NTP/Wheater sync every 1h.
4. Display: partial refresh only; full refresh every 24h.
5. Run on the 600 mAh JST LiPo.
6. Retry the OpenWeather request on failure.
7. Cache the weather result (RTC memory) across deep sleep.
8. Use HTTPS for the OpenWeather request.
9. Turn the display into a weather station only, dropping the clock; rename the project to InkWeather or PaperClima.