LoRa Modem

Firmware that presents a LoRa radio to a host as framed opaque bytes over a UART.

1. Requirements

• Python 3.6+
• A board with an SX127x-family radio (default environment: Arduino MKR WAN 1310)
• A USB-to-TTL adapter, if you want the debug output

2. Install PlatformIO

pip install platformio

First build downloads the toolchain and libraries into ~/.platformio (~300 MB).

3. Configure

Defaults are in src/config.h. Override any of them with build_flags in platformio.ini — every device on the link must be built with matching values for the first six:

flag	default
LORA_FREQUENCY_HZ	915000000L
LORA_SPREADING_FACTOR	7
LORA_BANDWIDTH_HZ	125000L
LORA_CODING_RATE	5
LORA_PREAMBLE_SYMBOLS	8
LORA_SYNC_WORD	0x2B
LORA_TX_POWER_DBM	17
LORA_MAX_PAYLOAD_BYTES	200
LORA_HOST_PORT	Serial
LORA_DEBUG_PORT	Serial1
LORA_HOST_BAUD	115200
LORA_TX_QUEUE_DEPTH	6
LORA_STATS_PERIOD_MS	30000UL

[env:mkrwan1310]
platform = atmelsam
board = mkrwan1310
build_flags =
    -D LORA_SYNC_WORD=0x4F
    -D LORA_SPREADING_FACTOR=9

On a board other than the MKR WAN, add the radio's pins:

    -D LORA_SS_PIN=10 -D LORA_RESET_PIN=9 -D LORA_DIO0_PIN=2

4. Build

pio run -e mkrwan1310

5. Upload

pio run -e mkrwan1310 -t upload

Add --upload-port <usb_port> if more than one board is attached.