ESP32 Integration

Real-time location data reception and parsing using the lec & lep commands.

In This Guide

we will walk you through the process of connecting a GrowSpace Developer Tag to an Arduino ESP32 board, and receiving and parsing real-time location data using the lec and lep commands. This step-by-step guide is designed to be beginner-friendly, even for those new to connecting ESP32 with tags. Unlike the UNO, the ESP32 supports multiple hardware serials, making it an ideal board for building compact test environments.

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Required Materials

Item	Purpose
ESP32 Board (e.g. DevKitC)	For serial data reception and parsing
GrowSpace Developer Tag	Location Data Transmitting Device
Arduino IDE	Code Writing and Upload
Jumper Cables (4-pin)	For connecting TX, RX, GND, 3.3V

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Arduino IDE Setup

Installation

• Download the installation file from the official Arduino IDE website. https://www.arduino.cc/en/software

• For Windows users, it is recommended to use the .msi installer.

Add ESP32 Board

• Launch the Arduino IDE. → File > Preferences

• In the Preferences window, add the following URL in the Additional Boards Manager URLs field:

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

• Tools > Board > Board Manager → Search for ESP32 and click Install for the ESP32 by Espressif Systems package.

• After installation, go to Tools > Board > ESP32 Dev Module

• Go to Tools > Port and select the automatically detected port for the ESP32.

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Serial Connection Setup

The left connector of the GrowSpace Developer Tag supports 3.3V serial communication. Connect the TX and RX pins of the tag to the TX2/RX2 pins on the ESP32 board as follows:

Developer Tag	ESP32 Board
TX	GPIO 16 (RX2)
RX	GPIO 17 (TX2)
GND	GND
3.3V	3.3V

⚠️ TX ↔ RX must be connected crossed (TX to RX and RX to TX). Example: TX → ESP32 RX, RX → ESP32 TX

Here is the pinout for the ESP32 DevKit. Please locate the TX2 and RX2 pins and make sure to connect them accurately as follows:

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Serial Relay Example Code

This code allows the ESP32 to relay serial data between a PC and a GrowSpace Developer Tag.

#define SERIAL2_RX 16  // GPIO16
#define SERIAL2_TX 17  // GPIO17

String inputFromSerial = "";
String inputFromSerial2 = "";

void setup() {
  Serial.begin(115200);
  Serial2.begin(115200, SERIAL_8N1, SERIAL2_RX, SERIAL2_TX);
  Serial.println("ESP32 Serial <-> Serial2 중계 (\\n 기준, \\r 추가, lep/lec 파싱)");
}

void loop() {
  // Serial 입력 → Serial2로 전송
  while (Serial.available()) {
    char ch = (char)Serial.read();
    if (ch != '\n') {
      inputFromSerial += ch;
    }

    if (ch == '\n') {
      Serial2.print(inputFromSerial);
      Serial2.print('\r');  // CR 추가
      inputFromSerial = "";
    }
  }

  // Serial2 입력 → 파싱 및 출력
  while (Serial2.available()) {
    char ch = (char)Serial2.read();
    inputFromSerial2 += ch;

    if (ch == '\n') {
      inputFromSerial2.trim();

      if (inputFromSerial2.startsWith("POS,")) {
        parseLEP(inputFromSerial2);
      } else if (inputFromSerial2.startsWith("DIST,")) {
        parseLEC(inputFromSerial2);
      } else {
        Serial.print("[Serial2 → Serial] 수신: ");
        Serial.println(inputFromSerial2);
      }

      inputFromSerial2 = "";
    }
  }
}

• Serial Monitor Setup: Set baud rate to 115200 bps and enable newline transmission.

• If the device information appears after entering the si command, the connection is successful.

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Example: Parsing Location Data (lep / lec commands)

A developer tag returns current location data using the lep or lec command. The example below shows how to parse the response and display it in a readable format.

Parse response from lep command (tag location data)

// ✅ LEP 결과 파서: POS,x,y,z,qf
void parseLEP(String line) {
  Serial.println("[LEP 위치 결과]");
  int idx = 0;
  String parts[5];

  while (line.length() > 0 && idx < 5) {
    int comma = line.indexOf(',');
    if (comma == -1) {
      parts[idx++] = line;
      break;
    } else {
      parts[idx++] = line.substring(0, comma);
      line = line.substring(comma + 1);
    }
  }

  Serial.print("X: "); Serial.println(parts[1]);
  Serial.print("Y: "); Serial.println(parts[2]);
  Serial.print("Z: "); Serial.println(parts[3]);
  Serial.print("품질(QF): "); Serial.println(parts[4]);
  Serial.println();
}

// 안전한 split 유틸(간단)
static void splitByComma(const String& s, std::vector<String>& out) {
  out.clear();
  int start = 0;
  while (start <= s.length()) {
    int comma = s.indexOf(',', start);
    if (comma == -1) {
      out.push_back(s.substring(start));
      break;
    } else {
      out.push_back(s.substring(start, comma));
      start = comma + 1;
    }
  }
}

Parse response from lec command (ranging + location data)

// ✅ LEC 결과 파서(안전한 토큰 파싱): DIST, n, (ANk, id, x, y, z, d)*, POS, x, y, z, qf
void parseLEC(String line) {
  Serial.println("[LEC 거리 + 위치 결과]");

  line.trim();
  std::vector<String> t;
  splitByComma(line, t);
  if (t.size() < 2 || t[0] != "DIST") {
    Serial.println("→ 형식 오류: DIST 헤더 없음");
    return;
  }

  int i = 1;
  int anchorCount = t[i++].toInt(); // 예: 4
  int parsedAnchors = 0;

  // Anchor 묶음 파싱: ANk, id, x, y, z, d
  while (i + 5 < (int)t.size() && t[i].startsWith("AN")) {
    String anLabel = t[i++];      // AN0, AN1, ...
    String anId    = t[i++];      // 3364, 35BE, ...
    float x = t[i++].toFloat();   // -1.00
    float y = t[i++].toFloat();   // 11.48
    float z = t[i++].toFloat();   // 0.00
    float d = t[i++].toFloat();   // 2.80

    Serial.print(anLabel); Serial.print(" (ID ");
    Serial.print(anId); Serial.print("): ");
    Serial.print("x="); Serial.print(x);
    Serial.print(", y="); Serial.print(y);
    Serial.print(", z="); Serial.print(z);
    Serial.print(" → 거리: "); Serial.print(d); Serial.println("m");

    parsedAnchors++;
  }

  if (parsedAnchors != anchorCount) {
    Serial.print("→ 경고: DIST가 가리킨 Anchor 수(");
    Serial.print(anchorCount);
    Serial.print(")와 실제 파싱 수(");
    Serial.print(parsedAnchors);
    Serial.println(") 불일치");
  }

  // POS, x, y, z, qf
  if (i < (int)t.size() && t[i] == "POS") {
    // parseLEP는 "POS,..." 전체 문자열을 기대하므로 그대로 만들어 전달
    String posLine = "POS";
    for (int k = i + 1; k < (int)t.size(); ++k) {
      posLine += ",";
      posLine += t[k];
    }
    Serial.println("▶ 태그 위치:");
    parseLEP(posLine);
  } else {
    Serial.println("→ POS 정보 없음");
  }
}

LEP execution result

LEC execution result

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Test Method Summary

• Upload the code and open the Serial Monitor in the Arduino IDE.

• Enter the lep or lec command.

• Check if the location data is displayed correctly (e.g., XYZ coordinates, distance).

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Conclusion

In this manual, we showed how to connect the GrowSpace developer tag to an ESP32, send location commands via serial communication, and receive and parse the data. This process allows real-time location tracking of a single tag, and can be extended to experiments using BLE transmission, Wi-Fi integration, or MQTT communication. If you don’t see any response during testing, please double-check the TX/RX pin connections and your serial port settings.