Documentation
Onboarding
Budget Planning Common Beginner Mistakes First Boot Learning Path Legal Basics for Beginners How the Beacon Saves Lives Understanding the Modes in One Page Morse Code for Beginners Parts Overview Reading the OLED Screens Radio Basics for Complete Beginners Safety First Tools You Need Using the BOM Builder Using the Interactive Demo Welcome to the Wiki
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Power & Battery
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Hardware & Components
Audio Alert System Audio Tone Details ESP32 Board Variants Button Types Guide Buzzer Types E22 Module Pinout E22 Radio Module Guide E22 vs Bare SX1262 ESP32 Board Guide ESP32 Board Variants ESP32 Deep Sleep Hardware ESP32 Flash and Partitions ESP32 Input-Only Pins ESP32 Sleep Modes ESP32 USB Chips Firmware OLED Rendering GPS Antenna Types GPS Module Buying Guide GPS Module Variants Hardware Components LED Status Indicators LED Indicators Wiring NEO-6M GPS Module Guide NEO-6M GPS Module NEO-6M vs NEO-M8N OLED Display OLED Library Notes OLED Panel Guide OLED Panel Life OLED Panel Specs OLED SPI vs I2C Display Selection Guide Display GPIO and Pin Reference ST7735 TFT Display HD44780 LCD Displays Radio Library and SX1262 Radio Module Variants
Build & Assembly
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Radio & RF Design
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Firmware & Software
Arduino CLI Guide Boot Loop Troubleshooting Boot Screens and Errors Changelog Code Style Guide Config Backup Config Dashboard Why the Dashboard Uses System Fonts CONFIG Payload Format Configuration Reference Dashboard HTTP API Dashboard Rendering ESP32 ADC Guide ESP32 Flash Security ESP32 Interrupts Guide ESP32 RTC Notes ESP32 Serial Debug Output ESP32 Timers Guide ESP32 WiFi Hardware esptool Guide Extending the Serial Protocol Factory Reset and Recovery Firmware CW Decoder Firmware System Monitoring Frequency Setting over Serial The Button System in Firmware How Firmware Loads Configuration Firmware Deep Sleep Firmware Error Codes Firmware GPS Handling The Firmware Main Loop Firmware NVS Keys Firmware Overview The Payload Builder Firmware RSSI Measurement The Scan Cycle in Detail Firmware Scan Engine The Firmware State Machine Firmware Tone Generation The TX Cycle in Detail Firmware TX Scheduler Upgrading to v5.5 Firmware Update in the Field Firmware Wake Sources The Watchdog Benchmark Demo Mode Flash Troubleshooting No Boot? Troubleshooting No Display? Troubleshooting NVS Configuration Store PlatformIO Guide RTC RAM State Battery Logging over Serial Serial Bridge Guide Serial Command Automation Serial Command Protocol Serial Debug System Serial Monitor Guide Software Build Process Unit Testing the Firmware Upload and Monitor What's New in v5.5 What's New in v6.0 WiFi and Security WiFi Configuration Portal WiFi Troubleshooting
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Modes & Operation
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Field Operations & Rescue
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Building Effectively
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Docs USB & Connectivity USB Power vs Data

USB Power vs Data

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What the beacon does over a power-only cable, a data cable, and an unpowered hub, and the pitfalls of each.

USB Power vs Data

The beacon can be powered over USB without ever talking to a computer, and it can talk to a computer without being powered by that computer’s port. Understanding the two channels avoids the most common “my port disappeared” confusion.

Power and data are separate

A USB cable has two channels:

  • Power (VBUS): always present, 5 V.
  • Data (D+/D-): present only in data cables and data-capable ports.

The beacon needs only power to boot and run. It needs both to be seen as a serial port.

Cable / portBeacon boots?Port appears?
Charge-only cableYesNo
Data cable into a laptopYesYes
Data cable into a phone chargerYesNo (charger has no data)
Data cable into a hubDependsDepends (see below)

The three realistic setups

1. Battery installed, cable for data. The 18650 powers the board; USB only carries data. This is the cleanest setup for long bridge sessions.

2. No battery, USB for power + data. The board runs from 5 V VBUS through the onboard regulator. Everything works, but the beacon draws from the computer; unplugging the cable kills it.

3. No battery, USB for data only (unpowered hub). A passive hub without its own supply may not provide enough current, and the ESP32 can brown-out mid-boot. Use a powered hub or keep a battery in.

Never power from two sources at once

With a battery installed AND a strong USB port, both feed the 5 V rail. The TP4056 charger in the standard build is designed for this (it prefers the higher source), but cheap clones without proper charging circuitry can misbehave. If your board has no charger, remove the battery before long USB sessions, or expect the battery to be topped up by the USB port when one is present.

Symptoms and causes

SymptomLikely cause
LED on, no COM portCharge-only cable
Port appears then vanishes during uploadBad cable / flaky connector; try another port and cable
Boot loop when USB is the only powerInsufficient supply; use a powered hub or add a battery
Bridge connects then drops when unpluggedYou were powering from USB only; keep the battery in