Project Overview
Pocket Beacon is a self-contained LoRa handheld/base station that aggregates data from remote sensor nodes and puts it in the palm of your hand. The unit features a Heltec V4 LoRa board paired with an OrangePi Zero2 single-board computer, a GPS module, and dual 10,000 mAh Li-Po cells — giving you 20,000 mAh, serious battery life in a compact, portable form factor that fits in a large pocket.
At its core, the device operates in two complementary modes:
Handheld Mode
Receive real-time notifications and view aggregated node data directly on the Heltec's on-board OLED screen. Carry it in the field to monitor your mesh network on the go. As of v1.1, exposed GPIO pins allow adding a buzzer, extra indicator LEDs, or other peripherals for customizable alerts and feedback.
Base Station Mode
The OrangePi serves a web dashboard over Wi-Fi — view every node on a live map, inspect sensor data, adjust node configurations, and manage the entire mesh from any device on the network.
The combination of LoRa's long-range, low-power radio with an on-board SBC means you get both offline utility and rich web-based management without needing any external infrastructure. GPS tagging lets you geolocate every node on the map dashboard, and the dual Li-Po configuration ensures extended runtime for field deployments.
Parts List
Click any row to open the product listing.
| Component | Qty | Notes | Image |
|---|---|---|---|
| Heltec WiFi LoRa 32 V4 | 1 | ESP32-S3 + SX1262 LoRa transceiver + 0.96" OLED. The brain of the radio side — handles LoRa mesh communication and displays node data on screen. | |
| GPS Module | 1 | Plugs directly into the Heltec V4 GPS header. Provides position data for geolocating the unit and its nodes on the web dashboard map. | |
| OrangePi Zero2 | 1 | Allwinner H616 SBC. Runs the web dashboard, hosts the Wi-Fi access point, and communicates with the Heltec V4 over UART for data relay. | |
| 5A Boost Converter | 1 | Small DC-DC boost module, pre-set to 5V output. Steps the Li-Po voltage (3.0–4.2V) up to a stable 5V rail for the OrangePi and peripherals. | |
| 10,000 mAh Li-Po Cell | 2 | Wired in parallel for 20,000 mAh total capacity. Spot-welded together and mounted inside the lower enclosure compartment. | |
| U.FL/IPEX to SMA Female Adapter | 3 | Pigtail adapters to bring the internal U.FL connectors (2× Heltec LoRa/Wi-Fi, 1× OrangePi Wi-Fi) out to panel-mount SMA jacks on the enclosure. | |
| Latching LED Switch | 1 | Main power switch with integrated LED indicator. Latching type — one press on, one press off. Mounts through the enclosure panel. |
Schematic
Below is a high-level wiring diagram showing how power flows from the parallel Li-Po pack through the latching switch and boost converter, then distributes to the Heltec V4 (via its charging port) and the OrangePi Zero2 (via 5V USB). The Heltec connects to the GPS module via its dedicated header, and the three U.FL pigtails route from the Heltec's two antenna ports and the OrangePi's Wi-Fi antenna to external SMA jacks.
Enclosure
The enclosure is designed for 3D printing (FDM) and consists of a main body shell, a battery compartment tray, and a snap-fit end cap. SMA antenna connectors, the latching LED switch, and any charging ports mount through cutouts in the side panels. No supports are required for printing, and dual-color printing is not necessary but helps with aesthetics if your printer supports it.
Build Guide
Step-by-step assembly instructions. Each step includes a photo placeholder for reference images.
Spot-weld batteries & insert into enclosure
Spot-weld the two 10,000 mAh Li-Po cells together in parallel (positive-to-positive, negative-to-negative). Important: Set your spot welder to a very low power setting — Li-Po cells are thin-walled and puncture-prone. Attach nickel strip leads for the positive and negative output. Test continuity, then seat the battery pack into the lower battery compartment of the enclosure.
Solder battery to switch, voltage regulator & Heltec charging port
Solder the battery pack's positive lead through the latching LED switch (so the switch controls the main power rail). Don't forget to also solder a ground wire to the switch's LED terminal so the indicator LED lights up when powered on. From the switch output, run wires to the input side of the 5A boost converter (set to 5V). Then tap the battery output to the Heltec V4's charging port input so the Heltec charges from the Li-Po pack directly.
Insert the 3 antenna adapters
Thread the three U.FL-to-SMA female pigtail adapters through their respective panel cutouts on the enclosure. Use a wrench to tighten the SMA nuts from the outside — hold the threads from the inside with your fingers and a strip of electrical tape for grip to prevent the pigtail from spinning.
Reconfigure Heltec board for external antenna
Required before connecting external antennas. On the bottom of the Heltec V4's ESP32-S3 module, locate the small inductor near the U.FL pad that routes the RF signal to the on-board PCB antenna. Carefully desolder this inductor, then bridge the pair of pads immediately adjacent to it — this reroutes the Wi-Fi RF path from the PCB trace antenna to the U.FL connector. Without this modification, the external antenna adapter will not function for Wi-Fi.
Attach Heltec antenna ports to adapters
Carefully snap two of the U.FL pigtail connectors onto the Heltec V4's LoRa and Wi-Fi U.FL antenna pads. Press straight down with even pressure — U.FL connectors are fragile. Leave the third pigtail free for the OrangePi.
Insert Heltec V4 & GPS module — glue GPS
Seat the Heltec V4 into its mounting position inside the enclosure. Plug the GPS module into the Heltec's GPS header, then apply two small drops of super glue to the sides of the GPS board to bond it securely to the enclosure wall. Allow a minute for the glue to set before moving on, simply hold with a clamp, or use super glue accelerator (1 teaspoon baking soda, 1/4 cup water).
Insulate & tighten the power switch
Before final mounting, wrap the body of the latching switch in a layer of electrical tape or Kapton (polyimide) tape to prevent any metal-on-metal shorts against the ESP32 or other nearby components. Then fully tighten the switch's panel nut from the outside of the enclosure using a wrench. Ensure the switch sits flush and doesn't wobble.
Glue down the voltage regulator
Apply a couple drops of super glue to the bottom of the boost converter module and press it into its designated spot inside the enclosure. This prevents it from shifting around during use or transport.
Insert OrangePi into enclosure & attach antenna adapter
Position the OrangePi Zero2 into its mounting area inside the enclosure. Snap the remaining U.FL pigtail connector onto the OrangePi's Wi-Fi antenna pad. Connect power from the boost converter's 5V output to the OrangePi via USB.
Solder UART lines
Solder the TX and RX lines from the Heltec V4's UART0 to the OrangePi's UART5 pins. Remember to cross them — the ESP32's TX goes to the Pi's RX, and vice versa. Also connect a common ground wire between the two boards.
Glue battery enclosure to bottom portion
Apply adhesive along the mating edges of the battery compartment tray and press it firmly onto the bottom section of the main enclosure body. Ensure alignment with the screw holes or snap features before the glue sets.
Snap in end cap & glue
Snap the end cap into the open side of the enclosure. Once seated, apply a thin bead of super glue along the seam to permanently seal it. Hold with clamps if necessary to keep it tight while curing. Wipe any excess glue and let it cure fully before powering on.
Notes
Battery safety: Always use a spot welder rated for Li-Po cells. Never solder directly to lithium battery terminals — excessive heat can cause thermal runaway. Use nickel strips and proper technique.
Boost converter calibration: Set the output to 5.0V before connecting any load. Use a multimeter to confirm. The OrangePi will brown-out below ~4.8V and may corrupt its SD card on unclean shutdown.
U.FL connector lifespan: U.FL connectors are rated for approximately 30 mating cycles. Avoid unnecessary disconnects during assembly. Press straight down, pull straight up.
Heat management: The OrangePi Zero2 can get warm under load. Consider adding a small heatsink to the SoC if running the web dashboard continuously. Ventilation holes in the enclosure design are recommended.
Serial communication: The Heltec V4 and OrangePi communicate over UART — specifically UART0 on the ESP32 and UART5 on the OrangePi. Make sure the OrangePi's OS is configured to listen on the correct /dev/ttyS5 device and that UART5 is enabled in the device tree overlay.
Charging: The Heltec V4 has on-board Li-Po charging via USB-C. With this wiring scheme, the pack charges when you plug USB-C into the Heltec — but charge current is limited by the Heltec's on-board charger IC. For faster charging, a dedicated BMS + TP4056 or similar module wired in parallel is recommended for future revisions.
Updates
Project revisions and modifications in reverse chronological order.
Expose GPIOs
Modified the enclosure design and Heltec V4 wiring to expose select GPIO pins through a breakout area on the side panel. This enables users to connect external peripherals — such as buzzers, indicator LEDs, relay modules, or additional sensors — without needing to open the enclosure. Wiring is routed from the ESP32-S3's available GPIO pads to a small pin header accessible from outside the case.
Coming Soon
Version 2.0 is in early planning. Here's what's on the roadmap:
Custom PCB
A purpose-built PCB to replace the current off-the-shelf module stack. Integrates the radio, power management, and SBC interface onto a single board — drastically shrinking the form factor and improving reliability.
LR1121 Radio Upgrade
Switching from the SX1262 to the LR1121 radio for increased transmit power and sensitivity. Longer range, better penetration through obstacles, and improved overall mesh reliability. The LR1121 also supports 2.4 GHz LoRa, enabling higher-bandwidth applications like voice transmission and bulk data transfer alongside the standard sub-GHz long-range link.
RPi Zero 2W (2GB)
Upgrading from the OrangePi Zero2 to a Raspberry Pi Zero 2W with 2GB RAM. Better software ecosystem, wider community support, and sufficient memory for more complex dashboard and data processing tasks.
Waterproofing
Redesigned enclosure with IP-rated gaskets, sealed SMA bulkheads, and a waterproof switch. Suitable for outdoor mounting and all-weather field deployment.
Solar Input
Integrated solar charge controller with a panel input jack. Enables indefinite deployment in sunny conditions — critical for remote base station installations where mains power isn't available.
1/4"-20 Mount
Standard 1/4"-20 threaded insert on the bottom of the enclosure. Mounts directly to tripods, camera mounts, RAM mounts, or custom bracket hardware for versatile field installation.