Concept Flow - HTTP requests from Arduino
Start Arduino
Connect to WiFi
Create HTTP Client
Send HTTP Request
Receive Response
Process Response
End or Repeat
Arduino connects to WiFi, sends an HTTP request, waits for response, then processes it.
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HTTP requests from Arduino - Step-by-Step Execution
Execution Sample
Arduino
void setup() {
WiFi.begin("SSID", "password");
while (WiFi.status() != WL_CONNECTED) {}
HTTPClient http;
http.begin("http://example.com");
int code = http.GET();
if (code > 0) {
String payload = http.getString();
}
http.end();
}
void loop() {
// put your main code here, to run repeatedly:
}This code connects Arduino to WiFi, sends a GET request to example.com, and reads the response.
Execution Table
| Step | Action | Condition/Status | Result/Output |
|---|---|---|---|
| 1 | Start WiFi connection | WiFi.status() != WL_CONNECTED | Connecting... |
| 2 | Wait for WiFi | WiFi.status() == WL_CONNECTED | Connected to WiFi |
| 3 | Create HTTPClient | N/A | HTTP client ready |
| 4 | Begin HTTP request | http.begin("http://example.com") | Connection opened |
| 5 | Send GET request | http.GET() | Response code received |
| 6 | Check response code | code > 0 | Valid response received |
| 7 | Read response | http.getString() | Payload stored in variable |
| 8 | End HTTP connection | http.end() | Connection closed |
| 9 | Finish | N/A | Program ready for next action |
💡 HTTP request cycle ends after closing connection with http.end()
Variable Tracker
| Variable | Start | After Step 2 | After Step 5 | After Step 7 | Final |
|---|---|---|---|---|---|
| WiFi.status() | WL_IDLE_STATUS | WL_CONNECTED | WL_CONNECTED | WL_CONNECTED | WL_CONNECTED |
| code | undefined | undefined | 200 | 200 | 200 |
| payload | empty | empty | empty | "<html>...</html>" | "<html>...</html>" |
Key Moments - 3 Insights
Why do we wait in a loop until WiFi.status() == WL_CONNECTED?
Because the Arduino needs to be connected to WiFi before sending HTTP requests. See execution_table step 2 where it waits until connected.
What does the code variable represent after http.GET()?
It holds the HTTP response code (like 200 for success). Check execution_table step 5 and 6 for this.
Why do we call http.end() at the end?
To close the HTTP connection and free resources. This is shown in execution_table step 8.
Visual Quiz - 3 Questions
Test your understanding
Look at the execution_table at step 5, what does http.GET() do?
💡 Hint
Check the 'Action' and 'Result/Output' columns at step 5 in execution_table
At which step does the Arduino confirm it is connected to WiFi?
💡 Hint
Look at the 'Condition/Status' column for WiFi.status() in execution_table
If the response code is 0 or negative, what happens?
💡 Hint
See execution_table step 6 where code > 0 is checked before reading payload
Concept Snapshot
Arduino HTTP Requests: 1. Connect to WiFi with WiFi.begin() 2. Wait until WiFi.status() == WL_CONNECTED 3. Create HTTPClient and call http.begin(url) 4. Send request with http.GET() 5. Check response code > 0 6. Read response with http.getString() 7. Close connection with http.end()
Full Transcript
This example shows how Arduino makes HTTP requests. First, it connects to WiFi and waits until connected. Then it creates an HTTP client and begins a connection to a URL. It sends a GET request and waits for the response code. If the response code is positive, it reads the response payload as a string. Finally, it closes the HTTP connection. Variables like WiFi.status(), code, and payload change during these steps. This process repeats as needed to communicate with web servers.