#include <ArduinoJson.h>

constexpr unsigned int MAX_DOC_SIZE {2000};
char JSONmessageBuffer[MAX_DOC_SIZE];

// template <typename T, const size_t ITEMS> void jsonAddArray(JsonObject &jdoc, const char *name, const T (&adata)[ITEMS]) {
//   JsonArray arr = jdoc.createNestedArray(name);
//   for (auto val : adata) { arr.add(val); }
// }

template <typename T, const size_t ITEMS> void jsonAddArray(JsonObject &jdoc, const char *name, const T (&adata)[ITEMS]) {
  for(unsigned int i = 0; i < ITEMS; ++i) {
    jdoc[name][i] = adata[i];
  }
}

void setup() {
  Serial.begin(115200);
  float a[] {1.25, -2.44, 1.556};
  double b[] {1.42, 1.91, -1.1};
  int c[] {2, 7, 4, 3};
  char d[][10] {"Eins", "Drei", "Sieben", "Fünfzehn"};

  StaticJsonDocument<MAX_DOC_SIZE> doc;
  JsonObject singleItem = doc.to<JsonObject>();
  singleItem["name"] = "Name";
  singleItem["ort"] = "Ort";

  jsonAddArray(singleItem, "array_a", a);
  jsonAddArray(singleItem, "array_b", b);
  jsonAddArray(singleItem, "array_c", c);
  jsonAddArray(singleItem, "array_d", d);
  singleItem["Ende"] = "Letzter Wert";

  serializeJsonPretty(doc, Serial);
  Serial.println();
  serializeJson(doc, JSONmessageBuffer);
  Serial.println(JSONmessageBuffer);
}

void loop() {}