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Arduino入門

2. デバイス&サンプル

6. アプリケーション

Unit C6L LoRa 通信

Unit C6L の LoRa 通信に関する API とサンプルプログラムです。

注意
Unit C6L は SX1262 LoRa トランシーバを使用します。開発時は必ず対応するクラスを選択してください。

サンプルプログラム

コンパイル要件

  • M5Stack ボードマネージャ バージョン >= 3.2.3
  • ボードオプション = M5UnitC6L
  • RadioLib ライブラリ バージョン >= 7.3.0

送信側

cpp
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#include <RadioLib.h>

// SX1262: NSS, DIO1, NRST, BUSY
SX1262 radio = new Module(23, 7, RADIOLIB_NC, 19);

// save transmission state between loops
int transmissionState = RADIOLIB_ERR_NONE;

// flag to indicate that a packet was sent
volatile bool transmittedFlag = false;

// this function is called when a complete packet is transmitted by the module
// IMPORTANT: this function MUST be 'void' type and MUST NOT have any arguments!
#if defined(ESP8266) || defined(ESP32)
ICACHE_RAM_ATTR
#endif

void setFlag(void) {
  // we sent a packet, set the flag
  transmittedFlag = true;
}

void setup() {
  delay(1000);
  Serial.begin(115200);

  // initialize SX1262
  Serial.print(F("[SX1262] Initializing ... "));
  // frequency, bandwidth, spreading factor, coding rate, sync word, power, preamble length, TCXO reference voltage, useRegulatorLDO
  int state = radio.begin(868.0, 125.0f, 12, 5, 0x34, 22, 20, 3.0, true);
  if (state == RADIOLIB_ERR_NONE) {
    Serial.println(F("success!"));
  } else {
    Serial.print(F("failed, code "));
    Serial.println(state);
    while (true) { delay(10); }
  }

  // set the function that will be called when packet transmission is finished
  radio.setPacketSentAction(setFlag);

  // start transmitting the first packet
  Serial.print(F("[SX1262] Sending first packet ... "));

  // you can transmit C-string or Arduino string up to 256 characters long
  transmissionState = radio.startTransmit("Hello world from M5Stack!");
}

// counter to keep track of transmitted packets
int count = 0;

void loop() {
  // check if the previous transmission finished
  if (transmittedFlag) {
    // reset flag
    transmittedFlag = false;

    if (transmissionState == RADIOLIB_ERR_NONE) {
      // packet was successfully sent
      Serial.println(F("transmission finished!"));

      // NOTE: when using interrupt-driven transmit method, it is not possible to automatically measure transmission data rate using getDataRate()

    } else {
      Serial.print(F("failed, code "));
      Serial.println(transmissionState);
    }

    // clean up after transmission is finished. This will ensure transmitter is disabled, RF switch is powered down etc.
    radio.finishTransmit();

    // wait a second before transmitting again
    delay(1000);

    // send another one
    Serial.print(F("[SX1262] Sending another packet ... "));

    // you can transmit C-string or Arduino string up to 256 characters long
    String str = "Hello world from M5Stack! #" + String(count++);
    transmissionState = radio.startTransmit(str);
  }
}

受信側

cpp
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#include <RadioLib.h>

// SX1262: NSS, DIO1, NRST, BUSY
SX1262 radio = new Module(23, 7, RADIOLIB_NC, 19);

// flag to indicate that a packet was received
volatile bool receivedFlag = false;

// this function is called when a complete packet is received by the module
// IMPORTANT: this function MUST be 'void' type and MUST NOT have any arguments!
#if defined(ESP8266) || defined(ESP32)
ICACHE_RAM_ATTR
#endif

void setFlag(void) {
  // we got a packet, set the flag
  receivedFlag = true;
}

void setup() {
  delay(1000);
  Serial.begin(115200);

  // initialize SX1262
  Serial.print(F("[SX1262] Initializing ... "));
  // frequency, bandwidth, spreading factor, coding rate, sync word, power, preamble length, TCXO reference voltage, useRegulatorLDO
  int state = radio.begin(868.0, 125.0f, 12, 5, 0x34, 22, 20, 3.0, true);
  if (state == RADIOLIB_ERR_NONE) {
    Serial.println(F("success!"));
  } else {
    Serial.print(F("failed, code "));
    Serial.println(state);
    while (true) { delay(10); }
  }

  // set the function that will be called when new packet is received
  radio.setPacketReceivedAction(setFlag);

  // start listening for LoRa packets
  Serial.print(F("[SX1262] Starting to listen ... "));
  state = radio.startReceive();
  if (state == RADIOLIB_ERR_NONE) {
    Serial.println(F("success!"));
  } else {
    Serial.print(F("failed, code "));
    Serial.println(state);
    while (true) { delay(10); }
  }
}

void loop() {
  // check if the flag is set
  if (receivedFlag) {
    // reset flag
    receivedFlag = false;

    // you can read received data as an Arduino String
    String str;
    int state = radio.readData(str);

    if (state == RADIOLIB_ERR_NONE) {
      // packet was successfully received
      Serial.println(F("[SX1262] Received packet!"));

      // print data of the packet
      Serial.print(F("[SX1262] Data:\t\t"));
      Serial.println(str);

      // print RSSI (Received Signal Strength Indicator)
      Serial.print(F("[SX1262] RSSI:\t\t"));
      Serial.print(radio.getRSSI());
      Serial.println(F(" dBm"));

      // print SNR (Signal-to-Noise Ratio)
      Serial.print(F("[SX1262] SNR:\t\t"));
      Serial.print(radio.getSNR());
      Serial.println(F(" dB"));

      // print frequency error
      Serial.print(F("[SX1262] Frequency error:\t"));
      Serial.print(radio.getFrequencyError());
      Serial.println(F(" Hz"));

    } else if (state == RADIOLIB_ERR_CRC_MISMATCH) {
      // packet was received, but is malformed
      Serial.println(F("CRC error!"));

    } else {
      // some other error occurred
      Serial.print(F("failed, code "));
      Serial.println(state);
    }
  }
}

実行結果

2 台の Unit C6L にそれぞれスケッチをコンパイルして書き込みます。送信側は LoRa 信号を送信し、受信側はその信号を受信します。各デバイスのシリアル出力は次のとおりです:

API

Unit C6L の LoRa 通信は RadioLib ライブラリをドライバとして使用します。詳細な API は以下のドキュメントを参照してください:

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