# Armachat FLIP > Pocket-sized open-source LoRa mesh messenger with ESP32-S3, RFM95 radio, 2.8" IPS display, and 36-key QWERTY keyboard. Runs Meshtastic and CircuitPython firmware for off-grid text communication. ## Quick Facts - **Brand:** Bobricius - **Board Type:** handheld-messenger - **Price:** ~$52.49 - **Product Readiness:** diy-kit - **CPU:** ESP32-S3 - **CPU Architecture:** Xtensa LX7 - **CPU Cores:** 2 - **RAM:** 512KB SRAM - **Flash:** varies by ESP32-S3 module - **USB:** USB-C - **Power:** 5V USB-C / 3.7V 18650 Li-ion - **Operating Voltage:** 3.3V - **Dimensions:** 115 x 95 x 18mm - **Charging Port:** USB-C - **Antenna:** Built-in PCB antenna - **Display:** 2.8" IPS LCD 320x240 ## Connectivity - **Wifi:** 802.11 b/g/n - **Bluetooth:** BLE 5.0 - **Lora:** SX1276 868/915MHz ## Open Source - **Firmware:** Yes - **Schematics:** Yes - **PCB Layout:** Yes ## Compatible Firmware meshtastic, circuitpython, arduino ## Use Cases - lora-mesh-networking - off-grid-communication - lora-messenger - portable-terminal - emergency-communication ## Components - **ESP32-S3** (mcu): Dual-core Xtensa LX7 @ 240MHz with WiFi and BLE 5.0 — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.espressif.com%2Fsites%2Fdefault%2Ffiles%2Fdocumentation%2Fesp32-s3_datasheet_en.pdf&ref=openhardware.directory&product=armachat-flip&source=md-export) - **RFM95** (radio): HopeRF LoRa transceiver (SX1276), 868/915MHz, +20dBm, -148dBm sensitivity — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.hoperf.com%2Fmodules%2Flora%2FRFM95.html&ref=openhardware.directory&product=armachat-flip&source=md-export) - **ST7789V** (display): 2.8" IPS LCD controller, 320x240 resolution, SPI interface — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.newhavendisplay.com%2Fappnotes%2Fdatasheets%2FLCDs%2FST7789V.pdf&ref=openhardware.directory&product=armachat-flip&source=md-export) - **TP4056** (power): 1A standalone linear Li-Ion battery charger with thermal regulation — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fdlnmh9ip6v2uc.cloudfront.net%2Fdatasheets%2FPrototyping%2FTP4056.pdf&ref=openhardware.directory&product=armachat-flip&source=md-export) - **SX1276** (radio): Semtech LoRa transceiver IC inside RFM95 module, 137-1020MHz, 168dB max link budget — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.semtech.com%2Fproducts%2Fwireless-rf%2Flora-connect%2Fsx1276&ref=openhardware.directory&product=armachat-flip&source=md-export) ## Protocols - **SPI** - **USB** - **UART** ## GPIO Map | Pin | Name | Type | Functions | |-----|------|------|-----------| | GP1 | Keyboard Column 1 | — | — | | GP2 | Keyboard Column 2 | — | — | | GP3 | Keyboard Column 3 | — | — | | GP4 | Keyboard Column 4 | — | — | | GP5 | Keyboard Column 5 | — | — | | GP6 | Keyboard Row 1 | — | — | | GP7 | Keyboard Row 5 | — | — | | GP8 | Keyboard Row 4 | — | — | | GP9 | Keyboard Row 2 | — | — | | GP10 | LoRa SPI SCK | — | — | | GP11 | LoRa SPI MOSI | — | — | | GP12 | LoRa SPI MISO | — | — | | GP13 | LoRa SPI CS | — | — | | GP14 | Keyboard Column 6 | — | — | | GP15 | Keyboard Row 3 | — | — | | GP16 | Display DC | — | — | | GP18 | Display SPI SCK | — | — | | GP19 | Display SPI MOSI | — | — | | GP20 | Display Backlight | — | — | | GP21 | Display SPI CS | — | — | | GP22 | Keyboard Row 6 | — | — | | GP28 | LoRa IRQ | — | — | ## Available Software - **[Meshtastic]()** (open-source) - **[Armachat CircuitPython Firmware]()** (open-source) ## Description ## Overview The Armachat FLIP is a pocket-sized "doomsday" LoRa mesh messenger designed by Slovak maker Bobricius for off-grid text communication without any cellular infrastructure. Built around an ESP32-S3 microcontroller and HopeRF RFM95 LoRa radio module (SX1276), it provides long-range mesh messaging with a standalone QWERTY keyboard and 2.8" IPS color display. The device supports dual firmware: **Meshtastic** for compatibility with the broader mesh networking ecosystem, and the custom **Armachat CircuitPython firmware** with AES-256 encryption, delivery confirmation, and automatic message resending. ## Hardware Design The FLIP uses a compact PCB design with all components on a single board: - **ESP32-S3** dual-core Xtensa LX7 @ 240MHz with WiFi and BLE 5.0 - **RFM95 (SX1276)** LoRa transceiver at 868MHz (EU) or 915MHz (US) with +20dBm output power - **ST7789V** 2.8" IPS LCD at 320x240 resolution - **36-key QWERTY keyboard** using Diptronic tactile switches (100gF/1N) in a 6x6 matrix - **TP4056** USB-C charging circuit for replaceable 18650 Li-ion battery - Separate charging module design for easy repair and replacement ## Pin Assignments ### LoRa Radio (SPI) | Signal | GPIO | |--------|------| | CS | GP13 | | SCK | GP10 | | MOSI | GP11 | | MISO | GP12 | | IRQ | GP28 | ### Display (SPI) | Signal | GPIO | |--------|------| | SCK | GP18 | | MOSI | GP19 | | DC | GP16 | | CS | GP21 | | Backlight | GP20 | ### Keyboard Matrix (6x6) - **Columns:** GP1, GP2, GP3, GP4, GP5, GP14 - **Rows:** GP6, GP9, GP15, GP8, GP7, GP22 ## Communication Range At maximum power (SF12, 125kHz bandwidth): - **700m** at ground level - **1.5km** from 4m elevation - **4.3km** from 10m elevation (intermittent) ## Firmware Options ### Meshtastic Standard Meshtastic firmware with BASE UI for standalone operation. Supports Bluetooth connection to phone apps for extended functionality. WiFi and Bluetooth noted as experimental on newer UI versions. ### Armachat (CircuitPython) Custom open-source firmware with features not available in Meshtastic: - AES-256 encrypted messaging - On-device message history and contact list - Delivery confirmation with automatic resend - Direct configuration via `/lib/config.py` - Configurable LoRa parameters (frequency, spreading factor, bandwidth, coding rate) ## Default LoRa Configuration ``` Frequency: 906.875 MHz (US) / 869.525 MHz (EU) Bandwidth: 125 kHz Coding Rate: 4/8 Spreading Factor: 12 Preamble Length: 32 TX Power: 15 dBm Sync Word: 0x2B ``` ## Open Source All firmware, schematics, and PCB designs are open source and available on GitHub. The CircuitPython firmware is fully transparent and user-modifiable. ## Important Notes This is an experimental device under active development, not a certified commercial product. The RFM95 radio module is not FCC/CE certified for commercial use. Intended for hobbyist, educational, and emergency preparedness applications. ## Where to Buy - [Lectronz](https://openhardware.directory/r?to=https%3A%2F%2Flectronz.com%2Fproducts%2Farmachat-meshtastic-compatible-lora-messenger&ref=openhardware.directory&product=armachat-flip&source=md-export) — $52.49 ## Resources - [product](https://openhardware.directory/r?to=https%3A%2F%2Flectronz.com%2Fproducts%2Farmachat-meshtastic-compatible-lora-messenger&ref=openhardware.directory&product=armachat-flip&source=md-export) - [github](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fbobricius%2Farmachat&ref=openhardware.directory&product=armachat-flip&source=md-export) - [wiki](https://openhardware.directory/r?to=https%3A%2F%2Fhackaday.io%2Fproject%2F171790-armawatch-armachat-long-range-radio-messengers&ref=openhardware.directory&product=armachat-flip&source=md-export) - [datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.espressif.com%2Fsites%2Fdefault%2Ffiles%2Fdocumentation%2Fesp32-s3_datasheet_en.pdf&ref=openhardware.directory&product=armachat-flip&source=md-export) - [schematics](https://openhardware.directory/r?to=https%3A%2F%2Fgithub.com%2Fbobricius%2FArmachat-circuitpython%2Ftree%2Fmain%2FHardware&ref=openhardware.directory&product=armachat-flip&source=md-export) ## Tags `lora`, `meshtastic`, `esp32-s3`, `off-grid`, `messenger`, `qwerty`, `circuitpython`, `mesh-networking`, `rfm95`, `handheld` ## Images ![Armachat FLIP](https://nbg1.your-objectstorage.com/openhardware-directory/entities/armachat-flip/32c1076f0709.jpg) > **Battery Powered:** 18650 --- [View full device page](https://openhardware.directory/devices/armachat-flip)