lorawan.cpp

#include "lorawan.h"

#if defined(ESP32)

#include "web_config.h"
#include "led_effects.h"
#include "sensor_console.h"
#include "util.h"
#include "ntp.h"

// Requires "MCCI LoRaWAN LMIC library", which will be automatically used with PlatformIO but should be added in "Arduino IDE"
// Tested successfully with v3.2.0 and connected to a thethingsnetwork.org app.
#include <lmic.h>
#include <SPI.h>
#include <hal/hal.h>
#include <arduino_lmic_hal_boards.h>

namespace config {
#if defined(CFG_eu868)
  const char *lorawan_frequency_plan = "Europe 868";
#elif defined(CFG_us915)
  const char *lorawan_frequency_plan = "US 915";
#elif defined(CFG_au915)
  const char *lorawan_frequency_plan = "Australia 915";
#elif defined(CFG_as923)
  const char *lorawan_frequency_plan = "Asia 923";
#elif defined(CFG_kr920)
  const char *lorawan_frequency_plan = "Korea 920";
#elif defined(CFG_in866)
  const char *lorawan_frequency_plan = "India 866";
#else
#  error "Region should be specified"
#endif
}

// Payloads will be automatically sent via MQTT by TheThingsNetwork, and can be seen with:
//   mosquitto_sub -h eu.thethings.network -t '+/devices/+/up' -u 'APPLICATION-NAME' -P 'ttn-account-v2.4xxxxxxxx-xxxxxxxxxx-xxxxxxxxxxxxxxxxxxxxxx' -v
//      or encrypted:
//   mosquitto_sub -h eu.thethings.network -t '+/devices/+/up' -u 'APPLICATION-NAME' -P 'ttn-account-v2.4xxxxxxxx-xxxxxxxxxx-xxxxxxxxxxxxxxxxxxxxxx' -v --cafile mqtt-ca.pem -p 8883
// ->
//   co2ampel-test/devices/esp3a7c94/up {"app_id":"co2ampel-test","dev_id":"esp3a7c94","hardware_serial":"00xxxxxxxx","port":1,"counter":5,"payload_raw":"TJd7","payload_fields":{"co2":760,"rh":61.5,"temp":20.2},"metadata":{"time":"2020-12-23T23:00:51.44020438Z","frequency":867.5,"modulation":"LORA","data_rate":"SF7BW125","airtime":51456000,"coding_rate":"4/5","gateways":[{"gtw_id":"eui-xxxxxxxxxxxxxxxxxx","timestamp":1765406908,"time":"2020-12-23T23:00:51.402519Z","channel":5,"rssi":-64,"snr":7.5,"rf_chain":0,"latitude":22.7,"longitude":114.24,"altitude":450}]}}
// More info : https://www.thethingsnetwork.org/docs/applications/mqtt/quick-start.html

namespace lorawan {
  bool waiting_for_confirmation = false;
  bool connected = false;
  char last_transmission[23] = "";

  void initialize() {
    Serial.print(F("Starting LoRaWAN. Frequency plan : "));
    Serial.print(config::lorawan_frequency_plan);
    Serial.println(F(" MHz."));

    // More info about pin mapping : https://github.com/mcci-catena/arduino-lmic#pin-mapping
    // Has been tested successfully with ESP32 TTGO LoRa32 V1, and might work with other ESP32+LoRa boards.
    const lmic_pinmap *pPinMap = Arduino_LMIC::GetPinmap_ThisBoard();
    // LMIC init.
    os_init_ex(pPinMap);
    // Reset the MAC state. Session and pending data transfers will be discarded.
    LMIC_reset();
    // Join, but don't send anything yet.
    LMIC_startJoining();
    sensor_console::defineIntCommand("lora", setLoRaInterval, F("300 (Sets LoRaWAN sending interval, in s)"));
  }

  // Checks if OTAA is connected, or if payload should be sent.
  // NOTE: while a transaction is in process (i.e. until the TXcomplete event has been received), no blocking code (e.g. delay loops etc.) are allowed, otherwise the LMIC/OS code might miss the event.
  // If this rule is not followed, a typical symptom is that the first send is ok and all following ones end with the 'TX not complete' failure.
  void process() {
    os_runloop_once();
  }

  void printHex2(unsigned v) {
    v &= 0xff;
    if (v < 16)
      Serial.print('0');
    Serial.print(v, HEX);
  }

  void onEvent(ev_t ev) {
    char current_time[23];
    ntp::getLocalTime(current_time);
    Serial.print(F("LoRa - "));
    Serial.print(current_time);
    Serial.print(F(" - "));
    switch (ev) {
    case EV_JOINING:
      Serial.println(F("EV_JOINING"));
      break;
    case EV_JOINED:
      waiting_for_confirmation = false;
      connected = true;
      led_effects::onBoardLEDOff();
      Serial.println(F("EV_JOINED"));
      {
        u4_t netid = 0;
        devaddr_t devaddr = 0;
        u1_t nwkKey[16];
        u1_t artKey[16];
        LMIC_getSessionKeys(&netid, &devaddr, nwkKey, artKey);
        //NOTE: Saving session to EEPROM seems like a good idea at first, but unfortunately: too much info is needed, and a counter would need to be save every single time data is sent.
        Serial.print(F("  netid: "));
        Serial.println(netid, DEC);
        Serial.print(F("  devaddr: "));
        Serial.println(devaddr, HEX);
        Serial.print(F("  AppSKey: "));
        for (size_t i = 0; i < sizeof(artKey); ++i) {
          if (i != 0)
            Serial.print("-");
          printHex2(artKey[i]);
        }
        Serial.println();
        Serial.print(F("  NwkSKey: "));
        for (size_t i = 0; i < sizeof(nwkKey); ++i) {
          if (i != 0)
            Serial.print("-");
          printHex2(nwkKey[i]);
        }
        Serial.println();
      }
      Serial.println(F("Other services may resume, and will not be frozen anymore."));
      // Disable link check validation (automatically enabled during join)
      LMIC_setLinkCheckMode(0);
      break;
    case EV_JOIN_FAILED:
      Serial.println(F("EV_JOIN_FAILED"));
      break;
    case EV_REJOIN_FAILED:
      Serial.println(F("EV_REJOIN_FAILED"));
      break;
    case EV_TXCOMPLETE:
      ntp::getLocalTime(last_transmission);
      Serial.println(F("EV_TXCOMPLETE"));
      break;
    case EV_TXSTART:
      waiting_for_confirmation = !connected;
      Serial.println(F("EV_TXSTART"));
      break;
    case EV_TXCANCELED:
      waiting_for_confirmation = false;
      led_effects::onBoardLEDOff();
      Serial.println(F("EV_TXCANCELED"));
      break;
    case EV_JOIN_TXCOMPLETE:
      waiting_for_confirmation = false;
      led_effects::onBoardLEDOff();
      Serial.println(F("EV_JOIN_TXCOMPLETE: no JoinAccept."));
      Serial.println(F("Other services may resume."));
      break;
    default:
      Serial.print(F("LoRa event: "));
      Serial.println((unsigned) ev);
      break;
    }
    if (waiting_for_confirmation) {
      led_effects::onBoardLEDOn();
      Serial.println(F("LoRa - waiting for OTAA confirmation. Freezing every other service!"));
    }
  }

  void preparePayload(int16_t co2, float temperature, float humidity) {
    // Check if there is not a current TX/RX job running
    if (LMIC.opmode & OP_TXRXPEND) {
      Serial.println(F("OP_TXRXPEND, not sending"));
    } else {
      uint8_t buff[3];
      // Mapping CO2 from 0ppm to 5100ppm to [0, 255], with 20ppm increments.
      buff[0] = (util::min(util::max(co2, 0), 5100) + 10) / 20;
      // Mapping temperatures from [-10°C, 41°C] to [0, 255], with 0.2°C increment
      buff[1] = static_cast<uint8_t>((util::min(util::max(temperature, -10), 41) + 10.1f) * 5);
      // Mapping humidity from [0%, 100%] to [0, 200], with 0.5°C increment (0.4°C would also be possible)
      buff[2] = static_cast<uint8_t>(util::min(util::max(humidity, 0) + 0.25f, 100) * 2);

      Serial.print(F("LoRa - Payload : '"));
      printHex2(buff[0]);
      Serial.print(" ");
      printHex2(buff[1]);
      Serial.print(" ");
      printHex2(buff[2]);
      Serial.print(F("', "));
      Serial.print(buff[0] * 20);
      Serial.print(F(" ppm, "));
      Serial.print(buff[1] * 0.2 - 10);
      Serial.print(F(" °C, "));
      Serial.print(buff[2] * 0.5);
      Serial.println(F(" %."));

      // Prepare upstream data transmission at the next possible time.
      LMIC_setTxData2(1, buff, sizeof(buff), 0);

      //NOTE: To decode in TheThingsNetwork:
      //        function decodeUplink(input) {
      //          return {
      //            data: {
      //              co2:  input.bytes[0] * 20,
      //              temp: input.bytes[1] / 5.0 - 10,
      //              rh:   input.bytes[2] / 2.0
      //            },
      //            warnings: [],
      //            errors: []
      //          };
      //        }
    }
  }

  void preparePayloadIfTimeHasCome(const int16_t &co2, const float &temperature, const float &humidity) {
    static unsigned long last_sent_at = 0;
    unsigned long now = seconds();
    if (connected && (now - last_sent_at > config::lorawan_sending_interval)) {
      last_sent_at = now;
      preparePayload(co2, temperature, humidity);
    }
  }

  /*****************************************************************
   * Callbacks for sensor commands                                 *
   *****************************************************************/
  void setLoRaInterval(int32_t sending_interval) {
    config::lorawan_sending_interval = sending_interval;
    Serial.print(F("Setting LoRa sending interval to : "));
    Serial.print(config::lorawan_sending_interval);
    Serial.println("s.");
    led_effects::showKITTWheel(color::green, 1);
  }
}

void onEvent(ev_t ev) {
  lorawan::onEvent(ev);
}

// 'A' -> 10, 'F' -> 15, 'f' -> 15, 'z' -> -1
int8_t hexCharToInt(char c) {
  int8_t v = -1;
  if ((c >= '0') && (c <= '9')) {
    v = (c - '0');
  } else if ((c >= 'A') && (c <= 'F')) {
    v = (c - 'A' + 10);
  } else if ((c >= 'a') && (c <= 'f')) {
    v = (c - 'a' + 10);
  }
  return v;
}

/**
 * Parses hex string and saves the corresponding bytes in buf.
 * msb is true for most-significant-byte, false for least-significant-byte.
 *
 * "112233" will be loaded into {0x11, 0x22, 0x33} in MSB, {0x33, 0x22, 0x11} in LSB.
 */
void hexStringToByteArray(uint8_t *buf, const char *hex, uint max_n, bool msb) {
  int n = util::min(strlen(hex) / 2, max_n);

  for (int i = 0; i < n; i++) {
    int j;
    if (msb) {
      j = i;
    } else {
      j = n - 1 - i;
    }
    uint8_t r = hexCharToInt(hex[j * 2]) * 16 + hexCharToInt(hex[j * 2 + 1]);
    buf[i] = r;
  }
}

// Load config into LMIC byte arrays.

void os_getArtEui(u1_t *buf) {
  hexStringToByteArray(buf, config::lorawan_app_eui, 8, false);
}

void os_getDevEui(u1_t *buf) {
  hexStringToByteArray(buf, config::lorawan_device_eui, 8, false);
}

void os_getDevKey(u1_t *buf) {
  hexStringToByteArray(buf, config::lorawan_app_key, 16, true);
}

#endif