Communication between Postman and Arduino - http

Question

I plan to send from a server a POST request to my Arduino Uno WiFi Rev2. More correctly, when the server sends this request a servomotor controlled by the Arduino should start moving. Right now, I'm using Postman to try and connect with the Arduino but I can't get it to work. So first I connect the Arduino to WiFi using my smartphone as a hotspot. This should be the unit's IP address, right?
I then try to send a POST request to this IP but it doesn't work. I'm also unsure which port number I should use, so I have just been trying with the standard ones (80, 4430, etc).
What am I doing wrong and how should I proceed?
EDIT: Here is my code.
#include <SPI.h>
#include <Servo.h>
#include <WiFiNINA.h>
char ssid[] = "MyNetwork"; // The network SSID
char pass[] = "testtest"; // The network password
int status = WL_IDLE_STATUS; // The Wifi radio's connection status
Servo servo_9; // Initializes the servomotor
WiFiServer server(80); // Server socket
//WiFiClient client;
WiFiClient client = server.available();
void setup() {
// Connects the servomotor to pin 9
servo_9.attach(9, 500, 2500);
// Initialize serial and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // Wait for serial port to connect. Needed for native USB port only
}
enable_WiFi();
connect_WiFi();
server.begin();
printCurrentNet();
printWifiData();
}
void loop() {
// Check the network connection once every 10 seconds:
delay(10000);
client = server.available();
if(client){
printWEB();
}
}
void enable_WiFi(){
// Check for the WiFi module:
if (WiFi.status() == WL_NO_MODULE) {
Serial.println("Communication with WiFi module failed!");
// Don't continue
while (true);
}
// Check if the latest Firmware version is installed
String fv = WiFi.firmwareVersion();
if (fv < WIFI_FIRMWARE_LATEST_VERSION) {
Serial.println("Please upgrade the firmware");
}
}
void connect_WiFi(){
// Attempt to connect to Wifi network:
while (status != WL_CONNECTED) {
Serial.print("Attempting to connect to WPA SSID: ");
Serial.println(ssid);
// Connect to WPA/WPA2 network:
status = WiFi.begin(ssid, pass);
// Wait 10 seconds for connection:
delay(10000);
}
// Now the arduino is connected, so print out the data:
Serial.print("You're connected to the network: ");
Serial.println();
}
void printCurrentNet() {
// Print the SSID of the network you're attached to:
Serial.print("SSID: ");
Serial.println(WiFi.SSID());
// Print the MAC address of the router you're attached to:
byte bssid[6];
WiFi.BSSID(bssid);
Serial.print("BSSID: ");
printMacAddress(bssid);
// Print the received signal strength:
long rssi = WiFi.RSSI();
Serial.print("Signal strength (RSSI): ");
Serial.println(rssi);
// Print the encryption type:
byte encryption = WiFi.encryptionType();
Serial.print("Encryption Type: ");
Serial.println(encryption, HEX);
Serial.println();
}
void printWifiData() {
Serial.println("Your board's IP and MAC address: ");
// Print your board's IP address:
IPAddress ip = WiFi.localIP();
Serial.print("IP Address: ");
Serial.println(ip);
// Print your MAC address:
byte mac[6];
WiFi.macAddress(mac);
Serial.print("MAC address: ");
printMacAddress(mac);
Serial.println();
}
// Find the MAC adress for your Arduino board
void printMacAddress(byte mac[]) {
for (int i = 5; i >= 0; i--) {
if (mac[i] < 16) {
Serial.print("0");
}
Serial.print(mac[i], HEX);
if (i > 0) {
Serial.print(":");
}
}
Serial.println();
}
void printWEB() {
if (client) { // if you get a client,
Serial.println("new client"); // print a message out the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected()) { // loop while the client's connected
if (client.available()) { // if there's bytes to read from the client,
char c = client.read(); // read a byte, then
Serial.write(c); // print it out the serial monitor
if (c == '\n') { // if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what's coming, then a blank line:
client.println("HTTP/1.1 200 OK");
client.println("Content-type:text/html");
client.println();
// The HTTP response ends with another blank line:
client.println();
// break out of the while loop:
break;
}
else { // if you got a newline, then clear currentLine:
currentLine = "";
}
}
else if (c != '\r') { // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
}
}
}
// close the connection:
client.stop();
Serial.println("client disconnected");
}
}
void servomotorGate(){
int position = 0;
for (position = 0; position <= 90; position += 1) {
servo_9.write(position);
Serial.println("Opening the gate");
}
delay(5000); // Wait for 5000 millisecond(s)
for (position = 90; position >= 0; position -= 1) {
servo_9.write(position);
Serial.println("Closing the gate");
}
}

Answer 1

I added the server client to listen for connections. However, the main reason why I couldn't connect to my IP address with Postman was that I was trying to get WiFi from my phone as a hotspot. I guess there is a problem with the port forwarding when using a hotspot. In the end, I solved the issue by connecting to a normal router WiFi network.