LoRaGateway - a real LoRa radio bridged to the gateway

Layer: Foundation · Build flags: PROTOCORE_ENABLE_LORA, PROTOCORE_ENABLE_GATEWAY

What this example teaches

The radio-plugin half of RadioGateway: instead of a simulated feed, this drives an actual Semtech SX127x / RFM95-96 over SPI and bridges its frames to the gateway.

RFM95 RX --SPI--> protocore_lora_recv() --> protocore_lora_frame_parse() --> protocore_gateway_uplink()
                                                              |
                                           envelope + topic  lora/0/<from>
                                                              |
                                                     northbound publish (MQTT/HTTP/WS)

The services/lora module has two layers, and only the first is hardware-specific:

• Driver - the SX127x register protocol over a protocore_lora_bus (two callbacks that read / write a chip register). Here they are a few SPI transfers; that is the only code tied to your board.
• Codec - protocore_lora_frame_parse / protocore_lora_frame_build handle the RadioHead 4-byte header (to / from / id / flags) that sits on top of the header-less LoRa PHY.

protocore_lora_config cfg = {}; cfg.freq_hz = 915000000; cfg.spreading = 7; cfg.bandwidth = 7;
cfg.coding_rate = 1; cfg.sync_word = 0x12; cfg.tx_power = 17;
protocore_lora_init(&bus, &cfg);           // verifies the chip id, applies the config
protocore_lora_set_rx(&bus);               // listen
 
int n = protocore_lora_recv(&bus, buf, sizeof(buf), &rssi);   // -> a frame, or -1
protocore_lora_header h; const uint8_t *payload; uint16_t plen;
protocore_lora_frame_parse(buf, n, &h, &payload, &plen);
protocore_gateway_uplink(0, h.from, payload, plen, rssi);      // bridge northbound

A downlink (a northbound command) is the mirror: protocore_lora_frame_build() then protocore_lora_send(), driven by the gateway port's transmit callback.

Wiring (ESP32 <-> RFM95)

RFM95	ESP32
SCK	GPIO 18
MISO	GPIO 19
MOSI	GPIO 23
NSS	GPIO 5
RST	GPIO 14
DIO0	GPIO 26
VCC	3V3
GND	GND

Change the PIN_* constants for your board. A production build triggers RX off the DIO0 interrupt and rides the DMA + FORWARD-lane path (RadioGateway); this sketch polls to stay simple. It needs the module wired to actually receive - the codec and the register protocol are host-tested in test/test_lora.

Build-flag note

The flags must reach the library build, so pass them as build flags:

pio ci --board=esp32dev --project-option="framework=arduino" \
  --project-option="build_flags=-DPROTOCORE_ENABLE_LORA=1 -DPROTOCORE_ENABLE_GATEWAY=1" \
  --lib="." examples/Drivers/LoRaGateway/LoRaGateway.ino