armoured-candles

A self-refreshing multi-exchange cryptocurrency candlestick chart for a Waveshare 7.5" V2 e-paper display (800×480), driven by a Seeed XIAO ESP32-S3.

The firmware fetches OHLCV data, renders candles + indicators into a 1-bit framebuffer, and serves a full browser-based control panel for configuration, preview, and OTA updates.

What's New

Compared to early versions, the project now includes:

• Multi-panel layouts (1 / 2 / 3 / 4 charts) rendered on a single 800×480 display
• Per-panel chart configuration (exchange, pair, interval, indicators, HA mode)
• Multi-exchange data support: Hyperliquid, Binance, AsterDEX, Kraken, and Poloniex
• Searchable coin picker with exchange-specific pair loading
• Live display preview in the web UI (/api/display bitmap stream)
• Browser OTA firmware updates (/api/update)
• Optional HTTP Basic Auth for UI/API protection
• Improved WiFi recovery with STA reconnect, ghost-link resets, and AP fallback

Features

• Candlestick charts on e-paper with OHLCV overlays
• Panel layouts: 1, 2, 3, or 4 charts simultaneously
• Indicators per panel: EMA fast/slow, RSI, and volume bars
• Exchange-aware intervals with auto candle count scaling
• Heikin Ashi rendering (optional per panel)
• Web config UI at http://epdchart.local (or device IP)
• Persistent settings in ESP32 NVS flash
• Partial/full refresh strategy to balance ghosting vs. speed
• mDNS + AP fallback setup flow
• In-browser OTA firmware upload/install

Hardware

Component	Model
MCU	Seeed XIAO ESP32-S3
Display	Waveshare 7.5" V2 (800×480 B/W), GDEY075T7
Driver HAT	Waveshare e-Paper Driver HAT Rev 2.3
Power	Stable 5V USB supply to the XIAO

Wiring

Important: For the Rev 2.3 HAT, both PWR and VCC should be tied to 3.3V. Using 5V on VCC can cause SPI corruption/snow.

HAT Pin	XIAO S3 Pin	GPIO
PWR	3V3	—
VCC	3V3	—
GND	GND	—
CLK	D8	GPIO7 (SCK)
DIN	D10	GPIO9 (MOSI)
CS	D1	GPIO2
DC	D2	GPIO3
RST	D3	GPIO4
BUSY	D4	GPIO5

HAT switch config: Display B, Interface 0 (4-wire SPI)

Arduino IDE Setup

1. Install ESP32 by Espressif Systems board package (3.x recommended)
2. Select board: XIAO_ESP32S3
3. Enable PSRAM: OPI PSRAM
4. Install library: ArduinoJson (Library Manager)

First Boot / Provisioning

1. Flash armoured-candles.ino
2. Device shows splash while attempting WiFi STA connect
3. If WiFi is missing/invalid, device starts AP: EPDChart-Setup
4. Join AP and open http://192.168.4.1
5. Enter WiFi + chart settings and save
6. Device reboots and starts normal chart refresh cycle

Web UI

Open: http://epdchart.local (or the local IP)

Sections

• Display Preview
  • Live image from /api/display
  • Auto refreshes in the browser
• Layout
  • Select 1, 2, 3, or 4 chart panels
  • Inactive slots are automatically dimmed in the editor
• Chart Panels (per slot)
  • Exchange, quote asset, coin search/select, interval
  • Auto/manual candle count
  • Heikin Ashi toggle
• Global Settings
  • Refresh interval
  • Full refresh cadence
  • Partial refresh threshold
  • Timezone offset
• WiFi
  • SSID/password updates
• Authentication
  • Optional username/password for HTTP Basic Auth
• Firmware Update
  • Upload compiled .bin and install OTA
• Actions
  • Save config, force refresh, reboot

Panel Gallery

Examples of panel layouts in action on the e-paper display:

Single panel

Two-panel split

Four-panel grid

Supported Exchanges

• Hyperliquid
• Binance
• AsterDEX
• Kraken
• Poloniex

The UI fetches tradable pairs per exchange directly in the browser, then stores each slot's selected pair in device config.

Interval Support

Intervals are exchange-aware and constrained by each provider. Common intervals include:

1m, 3m, 5m, 15m, 30m, 1h, 2h, 4h, 6h, 8h, 12h, 1d, 3d, 1w, 1M

Note: not every exchange supports every interval (the UI dynamically updates options).

Configuration Defaults

Stored in NVS (Preferences namespace epdchart):

Setting	Default	Range/Notes
Layout	1	1–4 panels
Refresh	5 min	1–60
Timezone offset	0 sec	UTC offset
Full refresh every	10 cycles	1–50
Partial threshold	40%	10–100
UI username	empty	optional (Basic Auth)
UI password	empty	optional (Basic Auth)

Per-panel defaults:

Setting	Default	Range/Notes
Exchange	hyperliquid	one of supported exchanges
Coin	ETH	exchange-dependent
Quote	USDT	exchange-dependent
Interval	5m	exchange-dependent
Auto candles	true	auto map by interval
Manual candles	60	5–200
EMA fast	9	2–100
EMA slow	21	2–200
RSI period	14	2–100
Heikin Ashi	false	on/off

Auto Candle Map

Interval	Candles
1m	120
3m	80
5m	60
15m	48
30m	48
1h	48
2h	42
4h	42
8h	30
12h	30
1d	30
3d	20
1w	26
1M	12

Network Resilience

• Periodic WiFi health checks
• Consecutive fetch failure tracking
• "Ghost" connection recovery via WiFi radio reset
• AP fallback mode while still retrying STA
• Status messaging on e-paper during outages

HTTP Endpoints

• GET / — Web UI
• GET /api/status — current runtime + config snapshot
• POST /api/config — save config
• POST /api/refresh — force redraw/update
• POST /api/restart — reboot device
• GET /api/display — current framebuffer as BMP
• POST /api/update/arm — arm OTA upload mode
• POST /api/update — OTA firmware upload stream

When UI auth is enabled, endpoints require HTTP Basic Auth.

Project Structure

armoured-candles/
├── armoured-candles.ino  # Main firmware: UI, WiFi, APIs, charts + indicators
├── epd7in5_V2.cpp/.h     # Waveshare 7.5" V2 driver (full + partial refresh)
├── epdif.cpp/.h          # Low-level SPI transport glue
├── splash_image.h        # Boot splash bitmap
└── docs/
    ├── splash_preview.png
    ├── panel_single.svg
    ├── panel_dual.svg
    └── panel_quad.svg

Known Notes

• Rev 2.3 HAT reset pin is reset-only (not hard power gate)
• PSRAM should be enabled for comfortable JSON/runtime headroom
• mDNS discovery can vary by client/network (use IP if needed)
• Partial refresh artifacts are expected over time; periodic full refresh clears them

License

MIT