LoRaEcho.ino

#include <RH_RF95.h>

#define RF95_CS  10
#define RF95_INT 2
#define RF95_RST 9

#define RF95_FREQ 915.0

RH_RF95 rf95(RF95_CS, RF95_INT);

// Message buffer
uint8_t data[RH_RF95_MAX_MESSAGE_LEN];

RH_RF95::ModemConfig modem = {0x72, 0x74, 0x00};

// Set the bandwidth for LoRa modem
void setBandwidth(uint32_t bw) {
  uint8_t index;
  uint32_t bandwidths[] = {
    7800,
    10400,
    15600,
    20800,
    31250,
    41700,
    62500,
    125000,
    250000,
    500000
  };
  for (index = 0x00; index < 9; index++) {
    if (bw <= bandwidths[index]) {
      break;
    }
  }
  modem.reg_1d = (modem.reg_1d & 0x0f) | (index << 4);
}

// Set the coding rate for LoRa modem
void setCodingRate(uint8_t d) {
  if (d == 5) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x02;
  } else if (d == 6) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x04;
  } else if (d == 7) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x06;
  } else if (d == 8) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x08;
  }
}

// Set the spreading factor for LoRa modem
void setSpreadingFactor(uint8_t sf) {
  if (sf < 6 || sf > 12) {
    return;
  }
  modem.reg_1e = (modem.reg_1e & 0x0f) | (sf << 4);
}

void setup()  {
  // Reset RF module
  pinMode(RF95_RST, OUTPUT);
  digitalWrite(RF95_RST, HIGH);
  delay(10);
  digitalWrite(RF95_RST, LOW);
  delay(10);
  digitalWrite(RF95_RST, HIGH);
  delay(10);
  // Init RF module
  rf95.init();
  rf95.setFrequency(RF95_FREQ);
  rf95.setTxPower(23, false);
  setBandwidth(250000);
  setCodingRate(8);
  setSpreadingFactor(10);
  rf95.setModemRegisters(&modem);
}

void loop() {
  if (!rf95.available()) {
    return;
  }
  uint8_t len = sizeof(data);
  if (!rf95.recv(data, &len)) {
    return;
  }
  if (len == 0) {
    return;
  }
  data[0] = 0x00;
  rf95.send(data, len);
  rf95.waitPacketSent();
}

LoRaRecv.ino

// Required base64 library:
// https://www.arduino.cc/reference/en/libraries/base64/
#include <Base64.h>
#include <RH_RF95.h>

#define RF95_CS  10
#define RF95_INT 2
#define RF95_RST 9

#define RF95_FREQ 915.0

RH_RF95 rf95(RF95_CS, RF95_INT);

// Message buffer
uint8_t data[RH_RF95_MAX_MESSAGE_LEN];

RH_RF95::ModemConfig modem = {0x72, 0x74, 0x00};

// Set the bandwidth for LoRa modem
void setBandwidth(uint32_t bw) {
  uint8_t index;
  uint32_t bandwidths[] = {
    7800,
    10400,
    15600,
    20800,
    31250,
    41700,
    62500,
    125000,
    250000,
    500000
  };
  for (index = 0x00; index < 9; index++) {
    if (bw <= bandwidths[index]) {
      break;
    }
  }
  modem.reg_1d = (modem.reg_1d & 0x0f) | (index << 4);
}

// Set the coding rate for LoRa modem
void setCodingRate(uint8_t d) {
  if (d == 5) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x02;
  } else if (d == 6) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x04;
  } else if (d == 7) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x06;
  } else if (d == 8) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x08;
  }
}

// Set the spreading factor for LoRa modem
void setSpreadingFactor(uint8_t sf) {
  if (sf < 6 || sf > 12) {
    return;
  }
  modem.reg_1e = (modem.reg_1e & 0x0f) | (sf << 4);
}

void setup()  {
  Serial.begin(9600);
  // Reset RF module
  pinMode(RF95_RST, OUTPUT);
  digitalWrite(RF95_RST, HIGH);
  delay(10);
  digitalWrite(RF95_RST, LOW);
  delay(10);
  digitalWrite(RF95_RST, HIGH);
  delay(10);
  // Init RF module
  rf95.init();
  rf95.setFrequency(RF95_FREQ);
  rf95.setTxPower(23, false);
  setBandwidth(250000);
  setCodingRate(8);
  setSpreadingFactor(10);
  rf95.setModemRegisters(&modem);
}

void loop() {
  if (!rf95.available()) {
    return;
  }
  uint8_t len = sizeof(data);
  if (!rf95.recv(data, &len)) {
    return;
  }
  // Messages are base64 encoded so that they can be
  // newline delimited over serial text
  int n = Base64.encodedLength(len);
  char data64[n];
  Base64.encode(data64, data, len);
  Serial.println(data64);
}

LoRaSend.ino

#include <RH_RF95.h>

#define RF95_CS  10
#define RF95_INT 2
#define RF95_RST 9

#define RF95_FREQ 915.0

RH_RF95 rf95(RF95_CS, RF95_INT);

// Message buffer
uint8_t data[RH_RF95_MAX_MESSAGE_LEN];

RH_RF95::ModemConfig modem = {0x72, 0x74, 0x00};

// Set the bandwidth for LoRa modem
void setBandwidth(uint32_t bw) {
  uint8_t index;
  uint32_t bandwidths[] = {
    7800,
    10400,
    15600,
    20800,
    31250,
    41700,
    62500,
    125000,
    250000,
    500000
  };
  for (index = 0x00; index < 9; index++) {
    if (bw <= bandwidths[index]) {
      break;
    }
  }
  modem.reg_1d = (modem.reg_1d & 0x0f) | (index << 4);
}

// Set the coding rate for LoRa modem
void setCodingRate(uint8_t d) {
  if (d == 5) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x02;
  } else if (d == 6) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x04;
  } else if (d == 7) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x06;
  } else if (d == 8) {
    modem.reg_1d = (modem.reg_1d & 0xf1) | 0x08;
  }
}

// Set the spreading factor for LoRa modem
void setSpreadingFactor(uint8_t sf) {
  if (sf < 6 || sf > 12) {
    return;
  }
  modem.reg_1e = (modem.reg_1e & 0x0f) | (sf << 4);
}

void setup()  {
  // Reset RF module
  pinMode(RF95_RST, OUTPUT);
  digitalWrite(RF95_RST, HIGH);
  delay(10);
  digitalWrite(RF95_RST, LOW);
  delay(10);
  digitalWrite(RF95_RST, HIGH);
  delay(10);
  // Init RF module
  rf95.init();
  rf95.setFrequency(RF95_FREQ);
  rf95.setTxPower(23, false);
  setBandwidth(250000);
  setCodingRate(8);
  setSpreadingFactor(10);
  rf95.setModemRegisters(&modem);
}

// Sends "Hello world!" with id=0x01 every 5 seconds
void loop() {
  // Set ID
  data[0] = 0x01;
  sprintf(data + 1, "Hello world!");
  rf95.send(data, 1 + strlen(data + 1));
  rf95.waitPacketSent();
  Serial.println("Done!");
  delay(5000);
}

usbserial.py

import datetime
from base64 import b64decode
try:
    from serial import Serial
    from serial.tools.list_ports import comports
except ImportError:
    print('pyserial not installed, try: pip install pyserial')
    exit(1)

device = None
for x in comports():
    device = x.device

if device is None:
    print('No device found')
    exit(1)

s = Serial(device)

while True:
    line = s.readline()
    data = b64decode(line)
    sender, data = data[0], data[1:]
    if sender != 0x00:
        # skip non-repeater messages
        continue
    now = datetime.datetime.now()
    print(now.strftime('%Y-%m-%d %H:%M:%S'), sender, data)