展示：开源电子墨水屏自行车码表

展示：开源电子墨水屏自行车码表
Show HN: Open-Source eInk Bike Computer

OpenTrailPaper 是一个基于 LilyGO T5S3 4.7 英寸电子墨水屏开发板的开源 DIY 自行车码表项目。它提供阳光下清晰可见的显示效果、GPS 导航、蓝牙传感器连接以及 FIT 文件记录功能，且骑行过程中无需联网或订阅服务。核心功能包括： * **离线使用：** 通过 iOS 配套应用加载路线和地图后，设备即可独立运行。 * **多功能性：** 支持 GPX 路线规划、转向提示、结构化训练和实时数据追踪。 * **硬件配置：** 配备 960×540 分辨率电子墨水屏、USB-C 接口以及用于数据存储的 SD 卡槽。 **注意事项：** 作为一个开发项目而非商业产品，它缺乏内置防水、气压高度计和耐用的实体按键。它最适合乐于动手、具有一定技术背景的自行车爱好者。该项目目前正在寻求社区贡献，特别是在改进 GPS、防水性能和传感器功能的硬件方案方面的建议。固件可通过基于 Chromium 内核的桌面浏览器轻松安装，用户可以自定义骑行数据和地图体验。

一位 Hacker News 用户近期发布了“OpenTrailPaper”，这是一个开源的电子墨水自行车码表。该项目的一大亮点是利用人工智能协助逆向工程未记录的寄存器，从而在 ESP32 芯片上实现了 ANT+ 无线协议。该项目在社区成员中引发了关于 DIY 自行车硬件挑战的技术讨论。争论的焦点包括不同电动自行车制造商之间通信协议（如 CAN 总线和私有 UART）的碎片化，以及实现系统通用兼容性的难度。评论者还提出了关于设备耐用性和性能的实际担忧。有人质疑电子墨水屏在阳光直射下是否依然清晰易读，以及硬件在暴雨等恶劣天气下的表现。尽管存在这些挑战，但开发者在专注于 BLE 的硬件上运行 ANT 协议的成就，依然引起了社区的浓厚兴趣。

OpenTrailPaper — DIY e-paper bike computer

DIY hardware · open-source firmware

OpenTrailPaper is firmware for the LilyGO T5S3 4.7" E-Paper PRO. It shows ride data and offline maps, follows GPX routes, records FIT files and connects to Bluetooth sensors. You buy and protect the board yourself.

01 — Device controls

Device walkthrough

Each item shows the screen it describes. Use the orange touch target on the device to move between related screens.

02 — Optional iPhone app

Use the app for setup and file transfer.

The iOS companion can plan and transfer routes, build offline maps, copy recorded rides, change settings and install firmware updates over Bluetooth. The head unit does not need the phone during a ride.

Plan a routeSearch for a destination, check the proposed route and send the GPX file to the device.

Copy recorded ridesTransfer rides from the device, then review the map, distance, power, heart rate and estimated ascent.

Settings and updatesSet FTP, timezone, units and backlight level, or install a firmware update over Bluetooth.

03 — Device and phone

What works without a phone

After routes and maps are loaded, the head unit can record and navigate by itself. There is no account or subscription. The app is used when you want to prepare or transfer data.

On the device — every ride

GPS tracking with speed, distance and a live map
Records each ride to a .fit file on the SD card
Turn-by-turn prompts along a loaded route
Runs structured workouts from .erg or .mrc files
Pairs with heart-rate & power sensors over Bluetooth
Works without a phone or data signal once maps and routes are loaded

In the app — setup and transfer

Plan a route and send it to the device
Build offline maps for a new area
Create workouts and arrange the device screens
Pull rides off the device and review them
Change settings and update the firmware

04 — Supported hardware

Currently supported on one board

OpenTrailPaper currently targets the LilyGO board below. It is a development project, not a finished or weatherproof retail product.

Strengths

A 4.7" e-paper panel that is readable in direct sunlight
An SD card slot for offline maps, routes, ride files and logs
GPS, capacitive touch, a front light, battery and USB-C on one board
Bluetooth 5 for heart-rate, power and cadence sensors
Firmware can be installed from a desktop Chromium browser over USB

Tradeoffs

No pressure sensor. There’s no barometric altimeter, so climbing is derived from elevation baked into the map tiles rather than measured — total ascent is an estimate.
Basic GPS. The receiver works, but a modern multi-band module would lock on faster and hold a fix better under tree cover or between buildings.
No magnetometer. Without a compass the map can only orient from your direction of travel, so it can’t point the right way while you’re stopped.
Measured baseline: about eight hours. A 1,500 mAh build ran for roughly 7.4 usable hours with the front light off. Power work is ongoing, so newer builds may differ.
Weak hardware buttons. Most interaction goes through the touch panel, which is fiddly with winter gloves or in the rain.
No waterproofing. The board ships bare with no seal or IP rating, so it needs a case or a bag of its own before you ride it in the wet.

Got a better board in mind?

Suggestions and pull requests welcome

Help wanted

A better target board would include a barometric altimeter, multi-band GPS, magnetometer, larger battery, usable hardware buttons and a weatherproof case. If you know of one, open an issue. Board ports are also welcome in the source repository.

Have the hardware?

Install the firmware and prepare an SD card.

The setup page flashes the board over USB and can build basic offline maps. It requires a desktop Chromium browser; the iOS app produces maps with elevation data.

Read setup instructions →