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CapiBridge is an open-source one-way gateway for low-power devices. It supports various communication technologies including LoRa, ESP-NOW, and WiFi. The gateway receives JSON strings from LoRa and ESP-NOW DIY devices and publishes them to an MQTT server. It automatically separates the JSON string into dynamic MQTT topics based on keys within the JSON, such as "b" for battery or "m" for motion, making it highly compatible with Home Assistant. This gateway simplifies adding new DIY nodes/sensors to your smart home by standardizing the communication protocol across all your DIY projects, focusing on simplicity and unified protocol handling.

• CapiBridge Full KIT or only Mainboard

If you prefer a DIY approach instead of buying a ready-made device, here are the links for antennas and cables.

• 2.4Ghz Antenna + Cable
• Cable UFL to SMA
• Antenna 433 MHz SMA male
• Antenna 868 MHz SMA male

• 1x LoRa Module 868 or 433MHz
• 2x ESP32-C3
• ESP1 Free GPIOs
  • IO7, IO10
• ESP2 Free GPIOs
  • IO10, IO3, IO1, IO0, IO4, IO5, IO6, IO7
• Power Pins 5V, 3.3V, GND
• USB-C with auto reset
• UART switch for selecting ( ESP1 | ESP2 )
• Buttons for flashing and reset
• Debug LEDs
  • USB - TX, RX
  • ESP1 to ESP2 - TX, RX
  • One LED for LoRa
  • One LED for ESP-NOW

View schematic. Click here

#include <Arduino.h>
#include <SPI.h>
#include <LoRa.h>
#include <WiFi.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
#include <esp_now.h>

CapiBridge is based on ESP32-C3 so If you are using ESP32 for the first time, you need To install the ESP32 board and all libraries, in your Arduino IDE.

• In your Arduino IDE, go to File> Preferences.
• Enter https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json into the “Additional Boards Manager URLs” field. Then, click the “OK” button
• Open the Boards Manager. Go to Tools > Board > Boards Manager and Search for ESP32 and press the install button for the “esp32 by Expressif Systems“
• Open Library Manager search for PubSubClient and press the install button, do the same for other libraries.

#define GATEWAY_KEY "xy"

#define WIFI_SSID "your_wifi_ssid"
#define WIFI_PASSWORD "your_wifi_passwd"
#define MQTT_USERNAME "your_mqtt_user"
#define MQTT_PASSWORD "your_mqtt_passwd"
#define MQTT_SERVER "your_mqtt_broker_address"
#define MQTT_PORT 1883

#define SIGNAL_BANDWITH 125E3  // signal bandwidth in Hz, defaults to 125E3
#define SPREADING_FACTOR 8    // ranges from 6-12, default 7 see API docs
#define CODING_RATE 5          // Supported values are between 5 and 8
#define SYNC_WORD 0xF3         // Any hexadecimal value from 0x00 to 0xFF. Dont use LoRaWAN/TTN "0x34"
#define PREAMBLE_LENGTH 6      // Supported values are between 6 and 65535.
#define TX_POWER 20            // TX power in dB, defaults to 17, Supported values are 2 to 20
#define BAND 433E6             // 433E6 / 868E6 / 915E6 - Depends on what board you bought.

// For sending 6 bytes "6 characters" of data using different Spreading Factors (SF), the estimated time on air (ToA)
// for each SF is as follows:

// SF7: Approximately 0.027 seconds (27.494 milliseconds)
// SF8: Approximately 0.052 seconds (52.224 milliseconds)
// SF9: Approximately 0.100 seconds (100.147 milliseconds)
// SF10: Approximately 0.193 seconds (193.413 milliseconds)
// SF11: Approximately 0.385 seconds (385.297 milliseconds)
// SF12: Approximately 0.746 seconds (746.127 milliseconds)
// These calculations demonstrate how the time on air increases with higher Spreading Factors
// due to the decreased data rate, which is a trade-off for increased communication range and signal robustness.

1. Open ESP1.ino sketch and configure config.h file see https://github.com/PricelessToolkit/CapiBridge?tab=readme-ov-file#esp1ino-sketch-configuration
2. Set the UART switch on the CapiBridge to the 'ESP1' position.

4. Click Upload and wait until the upload is done.
5. Set the UART switch on the CapiBridge to the 'ESP2' position.

Everything will be ready shortly; the CapiBridge RSSI entity should appear in the Home Assistant MQTT devices list within a minute or two.

{
  "k": "xy",
  "id": "ESP32",
  "b": "3.8",
  "rw": "Test123",
  "dr": "on"
}

Full Suported MQTT-Autodiscovery List

The simplest way to create JSON String without the ArduinoJson.h library and transmit it via LoRa. Example from MailBox sensor

#define NODE_NAME "mbox"
float volts = analogReadEnh(PIN_PB4, 12) * (1.1 / 4096) * (30 + 10) / 10;

// Send a message via LoRa
LoRa.print("{\"k\":\"xy\",\"id\":\"" + String(NODE_NAME) + "\",\"s\":\"mail\",\"b\":" + volts + "}");  

If your DIY sensor/assembly is not showing up in Home Assistant, here are some tips that may help you find the problem.

1. Check if the node LoRa settings are the same as the LoRa Gateway config, like Frequency, and spreading factor...
2. Connect CapiBridge to PC with switch position selected ESP1, open Arduino IDE Serial monitor "Speed 115200 baud" and check received JSON strings for errors.
3. Download MQTT Explorer and connect to your MQTT server. Check the homeassistant/sensor/Your_Node_Name topic for any errors.