带SIM卡和天线的MKR GSM 1400通过HTTP POST向Kaa云发送数据的Arduino代码问题排查

Let's break down why your Arduino code isn't working, even though the serial monitor says you're connected. I'll walk through the key issues and share a corrected version that matches your working cURL command.

Key Issues in Your Code #

1. Missing SSL/TLS Support for HTTPS #

Your code uses GSMClient, which is a plain TCP client. Kaa's endpoint uses HTTPS (port 443), so you need to use GSMSSLClient to establish a secure encrypted connection. Without this, your "connection" is just a raw TCP handshake—but the critical HTTPS handshake will fail silently, so no data actually gets transmitted to the cloud.

2. Malformed HTTP Request Format #

Your POST request has several formatting errors:

• You included the full https://connect.cloud.kaaiot.com:443 in the request line, but HTTP standards require only the path here. The server is specified via the Host header instead.
• You're missing mandatory headers:
  • Content-Type: application/json: Tells Kaa you're sending valid JSON data
  • Host: connect.cloud.kaaiot.com: Required for all HTTP/1.1 requests
• Your JSON payload doesn't match the working cURL command (yours is a single object, cURL uses an array of objects). While Kaa might accept single objects, aligning with your proven cURL request eliminates unnecessary variables.

3. Unnecessary Reconnection Spam #

Your loop calls client.connect(server, port) every iteration, which causes unnecessary connection churn. Instead, check if the client is already connected before attempting to reconnect.

4. No Server Response Debugging #

You never read the server's response after sending the request. This means you can't see error codes (like 401 Unauthorized for a bad token, or 400 Bad Request for invalid JSON) that would help you debug exactly what's going wrong.

5. Syntax Error in Unused Code #

The line String queryString = String(" \"temperature\": ) + String(temp) "); has unclosed quotes. Even though it's commented out, it's a bug waiting to happen if you uncomment it later.

Corrected Arduino Code #

Here's the fixed version that addresses all these issues:

#include <ArduinoHttpClient.h>
#include <MKRGSM.h>
#include <ArduinoJson.h>

const char PINNUMBER[] = "";
const char GPRS_APN[] = "";
const char GPRS_LOGIN[] = "";
const char GPRS_PASSWORD[] = "";
const String TOKEN = ""; // Fill in your endpoint token
const String APP_VERSION = ""; // Fill in your app version name

const unsigned long publishInterval = 5000UL; // 5 seconds
unsigned long lastPublish = 0;

// Use GSMSSLClient for HTTPS connections (critical for port 443)
GSMSSLClient client;
GPRS gprs;
GSM gsmAccess;

const char server[] = "connect.cloud.kaaiot.com";
const int port = 443;
HttpClient httpClient = HttpClient(client, server, port);

void setup() {
  Serial.begin(9600);
  while (!Serial); // Wait for serial monitor to connect (native USB only)

  Serial.println("Initializing GSM connection...");
  boolean connected = false;

  // Connect to GSM and GPRS network
  while (!connected) {
    if ((gsmAccess.begin(PINNUMBER) == GSM_READY) && 
        (gprs.attachGPRS(GPRS_APN, GPRS_LOGIN, GPRS_PASSWORD) == GPRS_READY)) {
      connected = true;
      Serial.println("GSM/GPRS connected successfully!");
    } else {
      Serial.println("Failed to connect. Retrying...");
      delay(1000);
    }
  }
}

void loop() {
  // Reconnect to server if disconnected
  if (!client.connected()) {
    Serial.println("Connecting to Kaa server...");
    if (client.connect(server, port)) {
      Serial.println("Connected to Kaa cloud!");
    } else {
      Serial.println("Server connection failed. Retrying in 3 seconds...");
      delay(3000);
      return; // Skip rest of loop if connection fails
    }
  }

  // Publish data at specified interval
  unsigned long now = millis();
  if (now - lastPublish >= publishInterval) {
    lastPublish = now;

    // Generate sample sensor data
    int temp = random(18, 24); // Range: 18-23 inclusive
    int humidity = random(40, 60);
    Serial.printf("Publishing data: temperature=%d, humidity=%d\n", temp, humidity);

    // Build the exact path from your working cURL command
    String path = "/kp1/" + APP_VERSION + "/dcx/" + TOKEN + "/json";

    // Send properly formatted POST request
    httpClient.beginRequest();
    httpClient.post(path);
    // Add required HTTP headers
    httpClient.sendHeader("Host", server);
    httpClient.sendHeader("Content-Type", "application/json");
    // Send Content-Length header (good practice for JSON payloads)
    String payload = "[{\"temperature\": " + String(temp) + ", \"humidity\": " + String(humidity) + "}]";
    httpClient.sendHeader("Content-Length", payload.length());
    // Finalize headers and send payload
    httpClient.endRequest();
    httpClient.print(payload);

    // Read and print server response for debugging
    Serial.println("\nServer response:");
    int statusCode = httpClient.responseStatusCode();
    Serial.printf("Status code: %d\n", statusCode);
    String responseBody = httpClient.responseBody();
    Serial.println(responseBody);
  }

  // Small delay to prevent loop spam
  delay(100);
}

Additional Tips #

• Fill in your credentials: Make sure you populate PINNUMBER, GPRS_APN, GPRS_LOGIN, GPRS_PASSWORD, TOKEN, and APP_VERSION with your actual values.
• Use serial output for debugging: The corrected code prints the server's status code and response body. This will immediately tell you if there's an authentication issue, invalid path, or malformed JSON.
• Power supply: MKR GSM 1400 uses significant power during GPRS/SSL connections. Use a robust power supply (not just USB) if running the device for extended periods.

内容的提问来源于stack exchange，提问作者Timor Bader