Go Reticulum is designed for field resilience and low-power hardware.

For detailed manufacturing instructions, complete bills of materials (BOM), Gerber files, pre-compiled firmware binaries, and one-click in-browser flashing, consult the Hardware Projects Guide.

• Compute: Raspberry Pi Zero 2W (quad-core 64-bit ARM)

• Display: 2.8" ST7789 SPI color LCD (320×240)

• Input: I2C M5Stack CardKB full QWERTY keyboard

• Radio: Semtech SX1262 LoRa transceiver (868/915 MHz)

• Power: 18650 Li-ion cell with integrated TP4056 charging circuit

• Software: Linux with Go Reticulum + NomadNet TUI

• Compute: Espressif ESP32-C5 (single-core RISC-V SoC with native 2.4/5 GHz Wi-Fi 6 and Bluetooth 5)

• Display: E-Paper or daylight-readable transflective LCD

• Radio: Integrated SPI Semtech SX1262 LoRa transceiver

• Battery Life: Multi-day standby runtime with deep-sleep support

• Compute: ESP32-C5 / ESP32-S3

• Operation: Headless, solar-powered mesh repeater and RRC relay daemon

• Connectivity: Simultaneously bridges LoRa mesh packets to a local Wi-Fi 6 SoftAP access point for nearby phones and laptops

The Go Reticulum Lifesaver (GRL) is a sovereign, pocket-sized off-grid survival communicator and field assistant designed around a sealed, low-cost (~$22.50 BOM) hardware puck. It pairs an Espressif ESP32-C5 RISC-V SoC with an SX1262 LoRa transceiver, a multi-constellation GNSS receiver, an electronic compass, and an optional cryptographic ASIC coprocessor.

T282828

Rather than burdening the device with fragile screens and tiny keyboards that inflate cost to $80–$150, GRL uses the smartphone already in the traveler's pocket:

• Automatic Captive Portal: When the user connects to the device's Wi-Fi 6 SoftAP (T383838Reticulum-Lifesaver-[ID]), iOS and Android automatically pop up the captive dashboard without installing any app, creating accounts, or requiring cellular service.

• In-Process Survival Engine: Wilderness first aid protocols (T383838med), repeater and cell tower catalogs (T383838tower near), solar/lunar ephemeris (T383838sun, T383838moon), geodetics (T383838whereami, T383838geo), and Plus Codes (T383838olc) resolve locally in microseconds with zero radio airtime and zero network hops.

• Radio for True Emergencies: LoRa radio airtime is reserved exclusively for broadcasting signed emergency SOS distress beacons, coordinating with human rescue parties, peer messaging, and syncing with hubs when reachable.

• Multi-Constellation GNSS: A high-sensitivity (-162 dBm) GNSS receiver (ATGM336H or Quectel L80) outputs standard NMEA-0183 sentences over UART at 9600 baud, deriving 10-character Plus Codes (Open Location Codes) and Maidenhead grid locators. Coordinates automatically inject into all operational commands.

• 3-Axis Digital Compass (RDF): A magnetometer (QMC5883L or LSM303DLHC) on I2C provides stationary 360° heading, unaffected by GPS stationary blindness. Combined with the World Magnetic Model (WMM2025), it calculates True North and delivers relative steering guidance for directional antennas (e.g. T383838Turn 15° RIGHT · 1 o'clock).

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| Component | Part / Specification | Approx. Cost | Source / Notes |

|---|---|---|---|

| Host MCU | Espressif ESP32-C5-DevKitC-1 | ~$4.00 | Dual-band Wi-Fi 6 (2.4/5 GHz), BLE 5, 240 MHz RV32, 8MB PSRAM |

| LoRa Radio | Semtech SX1262 SPI module (+22 dBm, 868/915 MHz) | ~$4.50 | Ebyte E22-900M22S or Ai-Thinker Ra-01SH |

| GNSS / GPS | ATGM336H or Quectel L80-M39 (ceramic patch antenna) | ~$3.50 | 3.3V UART, BDS/GPS/GLO, -162 dBm sensitivity |

| Compass / RDF | QMC5883L or LSM303DLHC (I2C breakout board) | ~$1.50 | 3.3V I2C, 360° stationary heading, relative antenna pointing |

| Storage | MicroSD card slot + 16GB FAT32 card | ~$3.00 | Stores offline survival manuals, topo maps, and logs |

| Battery & Power | 18650 Li-Ion cell (3000 mAh) + TP4056 USB-C charger | ~$4.00 | 3–5 days active standby; weeks on duty-cycled sleep |

| Enclosure | 3D-printed ruggedized PETG/TPU carabiner case | ~$2.00 | Compact, water-resistant, shock-absorbing |

| Total BOM | Complete sovereign off-grid communicator | ~$22.50 | 1/20th the cost of proprietary satellite hardware |

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| Subsystem | Signal Name | ESP32-C5 Pin | Direction | Description |

|---|---|---|---|---|

| SX1262 LoRa | T383838SCK | T383838GPIO 11 | Host $rightarrow$ Radio | SPI Bus Clock |

| | T383838MOSI | T383838GPIO 12 | Host $rightarrow$ Radio | SPI Data In |

| | T383838MISO | T383838GPIO 13 | Radio $rightarrow$ Host | SPI Data Out |

| | T383838CS# | T383838GPIO 14 | Host $rightarrow$ Radio | Active-low chip select |

| | T383838RST | T383838GPIO 15 | Host $rightarrow$ Radio | Hardware reset |

| | T383838BUSY | T383838GPIO 16 | Radio $rightarrow$ Host | Modem busy status line |

| | T383838DIO1 | T383838GPIO 17 | Radio $rightarrow$ Host | Packet received / TX done interrupt |

| GNSS (GPS) | T383838RX1 | T383838GPIO 9 | GNSS $rightarrow$ Host | NMEA-0183 serial stream (9600 baud) |

| | T383838TX1 | T383838GPIO 10 | Host $rightarrow$ GNSS | Optional configuration commands |

| Compass (I2C) | T383838SDA | T383838GPIO 21 | Bi-directional | I2C Data bus (QMC5883L / LSM303) |

| | T383838SCL | T383838GPIO 22 | Host $rightarrow$ Compass | I2C Clock bus |

| MicroSD | T383838DAT0 / T383838CLK / T383838CMD | T383838GPIO 18, 19, 20 | Bi-directional | Standard SD 1-bit or SPI mode |

| Power Sense | T383838BATT_ADC | T383838GPIO 1 (ADC1_CH0) | Analog In | Resistor divider to monitor battery voltage |

| Crypto ASIC | T383838CLK, T383838CS, T383838IO0..IO3, T383838IRQ | T383838GPIO 2..8 | Bi-directional | 7-Pin QSPI interconnect + interrupt (optional) |

!!! danger "Safety, Emergency & Medical Disclaimer"

GRL is an experimental open-source appliance. It is NOT a certified life-safety device, NOT a certified medical instrument, and NOT connected to official 911/112 dispatch or government search-and-rescue satellites. Transmission over unlicensed LoRa mesh frequencies is best-effort and never guaranteed. Always carry certified primary safety equipment (EPIRB/PLB, paper maps, magnetic compass). See the full legal and safety disclaimer for complete terms.

For complete software and configuration details, see the grl tool documentation and ASIC Plans §6.9–§6.12.

If purchasing ready-to-use hardware:

140

| Device | Frequency | Architecture | Notes |

|--------|-----------|--------------|-------|

| LilyGO TTGO T-Beam v1.1 / Supreme | 868 / 915 MHz | ESP32 / SX1262 | Built-in GPS, 18650 battery holder, OLED display |

| LilyGO T-Echo | 868 / 915 MHz | NRF52840 / SX1262 | Ultra-low power, sunlight-readable E-paper display, GPS |

| Heltec WiFi LoRa 32 (v3) | 868 / 915 MHz | ESP32-S3 / SX1262 | Compact, integrated 0.96" OLED |

| RNode (Custom PCB) | 433 / 868 / 915 MHz | ATmega1284P or ESP32 | Reference hardware designed by Mark Qvist |

All of these devices can be inspected, provisioned, and flashed using gornodeconf.