ChronoDisplay

An ESP32-based display panel for the FX Archery Chronograph (v1) that provides a real-time, always-on ePaper display of shot data via Bluetooth Low Energy (BLE). Compatible with airguns and archery applications.

Overview

ChronoDisplay connects wirelessly to the FX Archery Chronograph via BLE, receives speed readings in real time, and displays comprehensive shot statistics on a 7.5" monochrome ePaper screen. It runs entirely on an ESP32 — no PC or phone required.

Key Features

• Live BLE Connection — Automatically scans for, connects to, and maintains a link with the FX Chronograph
• Real-Time E-Paper Display — Always-on, sunlight-readable display showing:
  • Latest shot velocity (FPS) and energy (FPE)
  • Running shot count, average / min / max FPS
  • Spread and standard deviation
  • Profile info (gun name, power level, projectile type/caliber/weight)
  • Last 32 shot history
  • Real-time clock (EST timezone)
  • Connection status indicator
• Built-in Web Server — Configure everything from any browser on your WiFi network
  • Gun profiles (Bow/Airsoft, CO2 Pistol, Air Pistol, Air Gun UK, FAC)
  • Projectile profiles (pellets & slugs with caliber and weight)
  • Export all readings as CSV
  • Reset readings, format storage, toggle test mode
  • Accessible at http://esp32.local (mDNS) or the device's IP
• Persistent Storage — Gun and projectile profiles saved to LittleFS filesystem
• Test Mode — Generate simulated readings for display debugging

Hardware

Component	Specification
Microcontroller	ESP32
Display	7.5" Monochrome ePaper (UC8179 chipset, Screen Combo board ID: 502)
BLE Library	NimBLEDevice
Display Library	TFT_eSPI
Filesystem	LittleFS

Pin / Board Configuration

The board type is defined in driver.h:

#define BOARD_SCREEN_COMBO 502
#define USE_XIAO_EPAPER_DRIVER_BOARD

Ensure your User_Setup_Select.h (from TFT_eSPI) is configured for the XIAO ePaper driver board with a 7.5" UC8179 display.

Architecture

┌──────────────┐     BLE      ┌──────────────────┐     WiFi      ┌──────────────┐
│  FX Chrono   │ ◄──────────► │     ESP32        │ ◄──────────► │  Browser     │
│  (v1)        │   (speed     │                  │   (web UI)    │              │
│              │    data)     │  ┌──────────────┐│               │ 192.168.x.x  │
│              │              │  │  ChronoBLE   ││               │  esp32.local │
│              │              │  ├──────────────┤│               │              │
│              │              │  │  Display   │ │               │              │
│              │              │  ├──────────────┤│               │              │
│              │              │  │  WebServer │  │               │              │
│              │              │  ├──────────────┤│               │              │
│              │              │  │  FileMgr   │  │               │              │
│              │              │  └──────────────┘│               │              │
└──────────────┘              └──────────────────┘               └──────────────┘

Core Modules

Module	File(s)	Purpose
Main	ChronoDisplay.ino	Arduino setup/loop, orchestrates all subsystems
BLE Client	ChronoBLE.h/.cpp	NimBLE connection to FX Chronograph, reads speed notifications
Display	Display.h/.cpp	E-Paper rendering of all data fields
Web Server	ChronoWebServer.h/.cpp	HTTP server with embedded HTML/JS UI
File Manager	FileManager.h/.cpp	Persistent profile storage on LittleFS
Reading Manager	ChronoReadingManager.h/.cpp	Singleton that tracks all readings, profiles, and stats
Profiles	GunProfile.h/.cpp, ProjectileProfile.h/.cpp, ChronoProfile.h/.cpp	Gun and projectile profile data models
Reading	ChronoReading.h/.cpp	Individual shot reading (FPS + FPE + profile)

BLE Details

FX Chronograph BLE Characteristics

The device uses a custom GATT service with the following UUIDs:

Description	UUID
Device Info Service	0000180A-0000-1000-8000-00805F9B34FB
Chronograph Service	00001623-88EC-688C-644B-3FA706C0BB75
Speed Characteristic (notify)	00001624-88EC-688C-644B-3FA706C0BB75
Profile Setting Low	00001626-88EC-688C-644B-3FA706C0BB75
Battery Level	00001627-88EC-688C-644B-3FA706C0BB75
Profile Setting High	00001628-88EC-688C-644B-3FA706C0BB75

Speed data is received as a 2-byte big-endian value and converted to FPS by multiplying by 0.0475111859.

Connection Flow

1. Start BLE scan for devices advertising the Device Info Service UUID
2. When target found, connect using cached or new BLE client
3. Subscribe to the speed characteristic for notifications
4. Write low/high speed profile bytes to configure range
5. On disconnect, return to scan state and repeat

Web Interface

Connect to the device's WiFi network (or existing network — SSID and password are set in ChronoWebServer.cpp), then open:

• mDNS: http://esp32.local
• Direct IP: http://<ESP32-IP>

Available Pages & Endpoints

Route	Method	Purpose
/	GET	Main dashboard — select gun & projectile profiles, control panel
/gunprofile	GET	Form to add a new gun profile
/gunprofile/add	POST	Create a gun profile (name + type)
/gunprofile/set	POST	Activate a gun profile
/gunprofile/remove	POST	Delete a gun profile
/projectileprofile	GET	Form to add a projectile profile
/projectileprofile/add	POST	Create a projectile profile (name, type, caliber, weight)
/projectileprofile/set	POST	Activate a projectile profile
/projectileprofile/remove	POST	Delete a projectile profile
/export	GET	Download all readings as data.csv
/reset	GET	Clear all readings (shot count, stats)
/format	GET	Format LittleFS — erase all stored profiles
/testmode	GET	Toggle test mode (simulated readings every 5s)
/ota	GET	OTA firmware update page
/ota	POST	Upload and apply firmware update (.bin file)

Gun Profile Types

Type	Description
0	Bow / Airsoft
1	CO2 Pistol
2	Air Pistol
3	Air Gun UK
4	FAC (French)

Display Layout

┌──────────────────────────────────────────────────────────────────────────────────────────┐
│ 14:56 EST                                        ┌─────────────────────────────────┐    │
│ [Time]                                              │  Profile:                  │    │
│                                                      │  "My Rifle"     [1]        │    │
│    Latest Shot                                       │  .22 Pellet                │    │
│  ┌────────────────────┐                             │  Cal: 6.35               │    │
│  │                    │                             │  Pellet     0.58g        │    │
│  │      905 fps       │                             └─────────────────────────────────┘    │
│  └────────────────────┘                                      (Right Panel)              │
│                                                              │                           │    │
│ ┌─────────┐┌─────────┐┌─────────┐  ┌──────────────────────────────────────────┐         │    │
│ │Avg: 902│ │Count: 12│ │Spread: 5│  │Last Shots:                              │         │    │
│ └─────────┘└─────────┘└─────────┘  │ 12) 905 / 18.2  11) 904 / 18.2  ...  │         │    │
│ ┌─────────┐┌─────────┐┌─────────┐  └──────────────────────────────────────────┘         │    │
│ │Low: 897│ │High: 907│ │SD: 3.2 │                                                      │    │
│ └─────────┘└─────────┘└─────────┘                                                      │    │
│                                                                                        │    │
│  FPE: 18.2                                                                            │    │
└──────────────────────────────────────────────────────────────────────────────────────────┘

Development

Prerequisites

• Arduino IDE or PlatformIO
• ESP32 board support package
• TFT_eSPI library — configure User_Setup_Select.h for your display
• NimBLE-Arduino library

TFT_eSPI Configuration

In your TFT_eSPI User_Setup_Select.h, uncomment the XIAO ePaper 7.5" setup. The board constant used is BOARD_SCREEN_COMBO 502 with USE_XIAO_EPAPER_DRIVER_BOARD.

WiFi Configuration

Edit the SSID and password in ChronoWebServer.cpp:

const char *ssid = "your-network";
const char *password = "your-password";

Build & Upload

1. Configure libraries and board in Arduino IDE / PlatformIO
2. Set board to your ESP32 variant
3. Flash via USB

Project Status

Initial development. The project compiles and runs with the following functionality:

• ✅ BLE connection to FX Chronograph v1
• ✅ Live ePaper display of shot data
• ✅ Web-based gun & projectile profile management
• ✅ CSV export of readings
• ✅ Persistent profile storage
• ✅ Test mode for display debugging
• ✅ OTA firmware updates (via web UI at /ota)
• ✅ Time synchronization via NTP

License

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