# Responder NAV: an offline field computer

Carry a dedicated touchscreen for GPS navigation, LoRa messages, radio utilities and vehicle diagnostics without relying on cloud services.

## Hardware
M5Stack Tab5 (ESP32-P4 + ESP32-C6), Tab5 Keyboard, GPS and LoRa modules

The Tab5 runs custom firmware that reads GPS and radio modules and connects to external RTL-SDR and ELM327 OBD-II adapters. Its physical screen and keyboard bring the field tools together in one portable device.

## Shopping list

Base computer: Tab5, keyboard, storage and power. GPS, LoRa, SDR, OBD and camera are feature-specific additions, not a requirement to buy every expansion at once. The current repository is v0.73 beta.

Quantities are for one build. Unless marked source-specified, they are planning quantities; confirm kit contents and the chosen configuration before ordering.

### Confirm before buying
- Radio adapter revisions, ELM327 USB bridge, antennas, enclosure fasteners and power budget still need configuration-specific checks.

### 1 × M5Stack Tab5
- Requirement: Required
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: ESP32-P4 field-computer base.
- Destination: https://shop.m5stack.com/products/m5stack-tab5-iot-development-kit-esp32-p4
- Match: Product page
- Link review: Page checked; stock not assessed
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × Tab5 Keyboard (A164)
- Requirement: Required
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Physical input.
- Destination: https://shop.m5stack.com/products/keyboard-for-tab5
- Match: Exact product
- Link review: Page checked; stock not assessed
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × microSD card
- Requirement: Required
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Firmware, operating system or project storage.
- Notes: FAT32 or exFAT; copy the repository’s sdcard folder to the card root.
- Sourcing: No exact purchase link verified; confirm the model and requirements above before ordering.
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × USB-C data cable
- Requirement: Required
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Connect to the computer for programming or data.
- Notes: A charge-only cable cannot flash firmware. Example requires a USB-A host port. If your computer has only USB-C, use an appropriate USB-C data cable instead. Reuse the device’s included cable where possible; this is not a standalone power-supply recommendation.
- Destination: https://www.adafruit.com/product/4474
- Match: Accessory example: USB-A to USB-C, 1 m, data capable
- Link review: Page checked; stock not assessed
- Evidence: Setup requirement — check against your configuration
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer
- Source: https://www.adafruit.com/product/4474

### 1 × Computer for setup
- Requirement: Tool
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Build, configure or flash the software.
- Sourcing: Use existing equipment or match the specification above. No exact purchase link verified.
- Evidence: Setup requirement — check against your configuration
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × M5Stack Module GPS V2.0 with external antenna (AT6668)
- Requirement: Conditional
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: GPS functionality.
- Notes: V2.0 is end of life; V2.1 is not automatically a verified replacement.
- Destination: https://shop.m5stack.com/products/gps-module-v2-0-with-external-antenna-at6668
- Match: Exact product; end-of-life listing
- Link review: Page checked; stock not assessed
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × M5Stack U184-US915 LORAWAN-US915
- Requirement: Conditional
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: LoRa functionality.
- Notes: US915 only; includes the manufacturer antenna and HY2.0-4P cable. Confirm legality and the Tab5 connection for your configuration; do not substitute EU868.
- Destination: https://shop.m5stack.com/products/lorawan-unit-us915-stm32wle5-with-antenna
- Match: Exact U184-US915; region-specific
- Link review: Page checked; stock not assessed
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × RTL2832U receiver with R820T / R820T2 tuner
- Requirement: Conditional
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Radio and aircraft functions.
- Notes: Repository’s hardware guide specifies this target. The article also names Blog V4; do not assume V4 compatibility.
- Sourcing: No exact purchase link verified; confirm the model and requirements above before ordering.
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × USB ELM327 OBD-II adapter
- Requirement: Conditional
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Vehicle diagnostics.
- Notes: Exact USB serial bridge, vehicle and protocol support must be verified.
- Sourcing: No exact purchase link verified; confirm the model and requirements above before ordering.
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × Freenove FNK0060/FNK0060B ESP32-WROVER camera
- Requirement: Optional
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Deploy Cam companion.
- Notes: The creator targets CAMERA_MODEL_WROVER_KIT and the onboard CH340 USB serial bridge; an external FTDI programmer is not required. The kit’s 1GB card is not a replacement for the Tab5 application storage.
- Destination: https://store.freenove.com/products/fnk0060
- Match: Exact FNK0060 kit; select this board, not an ESP32-S3 camera
- Link review: Page checked; stock not assessed
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer
- Source: https://store.freenove.com/products/fnk0060
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer/blob/main/deploy_cam_esp32cam/README.md

### Per module × Radio antennas and matched connectors
- Requirement: Conditional
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Selected RF features.
- Notes: Choose the correct bands and connectors; the GPS listing includes its own external antenna.
- Sourcing: Use existing equipment or match the specification above. No exact purchase link verified.
- Evidence: Setup requirement — check against your configuration
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × Powered USB hub / stable peripheral power
- Requirement: Conditional
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Multiple or high-current USB peripherals.
- Notes: An unpowered hub may cause brownouts; foreground USB apps share the host controller.
- Sourcing: Use existing equipment or match the specification above. No exact purchase link verified.
- Evidence: Setup requirement — check against your configuration
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 set × 3D-printed enclosure and assembly hardware
- Requirement: Required
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: House the complete field computer.
- Notes: Exact fastener counts depend on the enclosure revision.
- Sourcing: No exact purchase link verified; confirm the model and requirements above before ordering.
- Evidence: Creator source
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

### 1 × Tab5 power / NP-F550 battery
- Requirement: Conditional
- Quantity basis: Planning quantity for one build; check the selected configuration
- Purpose: Power the device.
- Notes: Standard Tab5 has no battery; Tab5 Kit includes NP-F550. Check the selected bundle and peripheral load.
- Sourcing: Use existing equipment or match the specification above. No exact purchase link verified.
- Evidence: Setup requirement — check against your configuration
- Source: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

Source reviewed, not assembled or hands-on tested. A working product page does not confirm stock, firmware compatibility or a complete build.

## Setup
Multi-device setup

## Coding tool
OpenAI Codex

## How the agent helped
Creator Alberto Cajiao explicitly says OpenAI Codex was used extensively for firmware implementation, debugging, refactoring and rapid prototyping. The article documents the assembled hardware and current functions separately from future plans.

## Before you build
This is an expandable prototype, not a finished appliance. Different features need their own modules or USB adapters, and the enclosure is 3D printed. The article names both RTL2832U/R820T2 and RTL-SDR Blog V4 hardware; check the repository for the supported receiver. Radio frequencies and transmission rules vary by location. Vehicle functions are diagnostic; do not operate the device while driving.

## Sources
- Original build: https://hackster.io/albertocajiaoac/responder-nav-an-expandable-offline-field-computer-28db01
- Supporting source: https://github.com/fistulareffigy/Responder-NAV-Field-Computer

Source reviewed 2026-11-04. Not hands-on tested.