HTTP Integration with BLYNK


i want to use the BLYNK App for visualization of the incoming and decoded payload.
HTTP integration works well by using the GET method in TTN<BLYNK_TOKEN>/update/v0?value=12345” (in this case the value “12345” is pushed to the BLYNK App on PIN V0)

Is it possible to insert value from the decoded payload (e.g. “decoded.myDecodedValue”)?

something like that: “<BLYNK_TOKEN>/update/v0?value=decoded.myDecodedValue”


No, that would need an intermediate server (which could then also subscribe to MQTT directly, without using the HTTP Integration). See HTTP Integration: pass only payload_fields.

here is some example code which runs on a server (e.g. ESP8266) and forwards the incoming data (JSON from HTTP integration from TTN servers) and sends it to your blynk server. :slight_smile:

tested successfully and using it for month already.

in the setup:

  server.on("/<specified in the http integration>/", HTTP_POST, send_ttn_to_blynk);
void send_ttn_to_blynk() {
  const size_t capacity = JSON_ARRAY_SIZE(1) + JSON_OBJECT_SIZE(1) + JSON_OBJECT_SIZE(6) + 2 * JSON_OBJECT_SIZE(10) + 610;
  DynamicJsonDocument doc(capacity);
  String json_string = server.arg("plain");
  deserializeJson(doc, json_string);
  String payload_raw = doc["payload_raw"];

  char payload_raw_char[payload_raw.length() + 1];
  payload_raw.toCharArray(payload_raw_char, payload_raw.length() + 1);
  int decodedLen = base64_dec_len(payload_raw_char, sizeof(payload_raw_char));
  char decoded[decodedLen];
  base64_decode(decoded, payload_raw_char, sizeof(payload_raw_char));
  String decoded_data_string = String(decoded);

// data in this example is battery and position of a gps tracker sending its data via ttn

  int first_comma = decoded_data_string.indexOf(",");
  int second_comma = decoded_data_string.indexOf(",", first_comma + 1);
  int third_comma = decoded_data_string.indexOf(",", second_comma + 1);
  int v_pos = decoded_data_string.indexOf("V");
  String lat = decoded_data_string.substring(first_comma + 1, second_comma);
  String lon = decoded_data_string.substring(second_comma + 1 , third_comma);
  String bat_voltage = decoded_data_string.substring(v_pos + 1, v_pos + 4);
  server.send(200, "text/html", "OK");

  WiFiClient client;
  HTTPClient http;
  if (http.begin(client, "http://insert your server here:insert your port/insert blynk sec auth t/update/V7?value=" + String(pos_index) + "&value=" + lat + "&value=" + lon + "&value=" + bat_voltage + "V")) {
    int httpCode = http.GET();
    if (httpCode > 0) {
      if (httpCode == HTTP_CODE_OK || httpCode == HTTP_CODE_MOVED_PERMANENTLY) {
        String api_answer = http.getString();