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Topic: Weird issue when using 433 RF transmitter and ethernet shield (Read 1 time) previous topic - next topic


Hello Everyone,
Can you please give me your opinion on something I am working on? I am stuck on the same error for days and I can't figure this one out.

I modified W.A. Smith's SD Card Web Server I/O tutorial to fit my needs, the tutorial is great and I completed it with no issues.
I added a DHT11 sensor for temperature and humidity for this setup and I would like to use an RF transmitter to remotely operate my radio controlled power outlets.

I read the values from the remote and I created a sketch that can turn on and off each outlet - so that part is working fine.
I am able to read and display the DHT sensor values and I can control LED-s remotely from the SD card hosted website.

But when I try to modify the script to send a " mySwitch.send();" command instead of turning on the LED, it translates fine, I can upload to the Arduino but I can't access the webpage this way... the request times out and nothing happens.

My RF transmitter is on pin7 and the DHT is on pin 2.
I tried to use other available pins but didn't help. I am using an Uno with 328-PU.
The website is hosted on the sD card.

I attached my code, please advice, any suggestion is highly appreciated since I am out of ideas on my own:

Code: [Select]


Pin0: Free
Pin1: Free
Pin2: DHT
Pin3: Free
Pin4: SD?
Pin5: Free
Pin6: Free
Pin7: RF
Pin8: Free
Pin9: Free
pin10: Ethernet?
Pin11: Ethernet?
Pin12: Ethernet?
Pin13: Ethernet?

A0: Ethernet
A1: Ethernet
Based on the script by Author:  W.A. Smith, http://startingelectronics.com

#include <SPI.h>
#include <Ethernet.h>
#include <SD.h>
#include <RCSwitch.h>
#include "DHT.h"
// size of buffer used to capture HTTP requests
#define REQ_BUF_SZ   60
#define DHTPIN 2
#define DHTTYPE DHT11

RCSwitch mySwitch = RCSwitch();
int RCTransmissionPin = 7;

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip(192,168,1,177);
EthernetServer server(80);
File webFile;
char HTTP_req[REQ_BUF_SZ] = {0};
char req_index = 0;
boolean LED_state[4] = {0};


void setup()
  // disable Ethernet chip
  pinMode(10, OUTPUT);
  digitalWrite(10, HIGH);

  Serial.begin(9600);       // for debugging

  // initialize SD card
  Serial.println("Initializing SD card...");
  if (!SD.begin(4)) {
    Serial.println("ERROR - SD card initialization failed!");
    return;    // init failed
  Serial.println("SUCCESS - SD card initialized.");
  // check for index.htm file
  if (!SD.exists("index.htm")) {
    Serial.println("ERROR - Can't find index.htm file!");
    return;  // can't find index file
  Serial.println("SUCCESS - Found index.htm file.");

  Ethernet.begin(mac, ip);  // initialize Ethernet device
  server.begin();           // start to listen for clients

  //initialize RF Transmiter
  mySwitch.enableTransmit( RCTransmissionPin );

  //Initialize DHT sensor
  pinMode(9, OUTPUT);

void loop()
  EthernetClient client = server.available();  // try to get client
  if (client) {  // got client?
    boolean currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {   // client data available to read
        char c = client.read(); // read 1 byte (character) from client
        // limit the size of the stored received HTTP request
        // buffer first part of HTTP request in HTTP_req array (string)
        // leave last element in array as 0 to null terminate string (REQ_BUF_SZ - 1)
        if (req_index < (REQ_BUF_SZ - 1)) {
          HTTP_req[req_index] = c;          // save HTTP request character
        // last line of client request is blank and ends with \n
        // respond to client only after last line received
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          // remainder of header follows below, depending on if
          // web page or XML page is requested
          // Ajax request - send XML file
          if (StrContains(HTTP_req, "ajax_inputs")) {
            // send rest of HTTP header
            client.println("Content-Type: text/xml");
            client.println("Connection: keep-alive");
            // send XML file containing input states
          else {  // web page request
            // send rest of HTTP header
            client.println("Content-Type: text/html");
            client.println("Connection: keep-alive");
            // send web page
            webFile = SD.open("index.htm");        // open web page file
            if (webFile) {
              while(webFile.available()) {
                client.write(webFile.read()); // send web page to client
          // display received HTTP request on serial port
          // reset buffer index and all buffer elements to 0
          req_index = 0;
          StrClear(HTTP_req, REQ_BUF_SZ);
        // every line of text received from the client ends with \r\n
        if (c == '\n') {
          // last character on line of received text
          // starting new line with next character read
          currentLineIsBlank = true;
        else if (c != '\r') {
          // a text character was received from client
          currentLineIsBlank = false;
      } // end if (client.available())
    } // end while (client.connected())
    delay(1);      // give the web browser time to receive the data
    client.stop(); // close the connection
  } // end if (client)

void SetLEDs(void)
//switch1 ON
  if (StrContains(HTTP_req, "Kapcsolo1ON")) {
  mySwitch.send(4527411, 24);

//switch1 OFF
  if (StrContains(HTTP_req, "Kapcsolo1OFF")) {
  mySwitch.send(4527420, 24);
  if (StrContains(HTTP_req, "Kapcsolo2ON")) {
  mySwitch.send(4527555, 24);

  if (StrContains(HTTP_req, "Kapcsolo2OFF")) {
  mySwitch.send(4527564, 24);

  if (StrContains(HTTP_req, "Kapcsolo3ON")) {
  mySwitch.send(4527875, 24);

  if (StrContains(HTTP_req, "Kapcsolo3OFF")) {
  mySwitch.send(4527884, 24);

  if (StrContains(HTTP_req, "MindenON")) {
  mySwitch.send(4527411, 24); 
  mySwitch.send(4527555, 24); 
  mySwitch.send(4527875, 24);

  if (StrContains(HTTP_req, "MindenOFF")) {
  mySwitch.send(4527420, 24); 
  mySwitch.send(4527464, 24); 
  mySwitch.send(4527884, 24);


// send the XML file with analog values, switch status
//  and LED status
void XML_response(EthernetClient cl)
  //int analog_val;            // stores value read from analog inputs
  int count;                 // used by 'for' loops
  float h = dht.readHumidity();
  float t = dht.readTemperature();

  cl.print("<?xml version = \"1.0\" ?>");




// sets every element of str to 0 (clears array)
void StrClear(char *str, char length)
  for (int i = 0; i < length; i++) {
    str[i] = 0;

// searches for the string sfind in the string str
// returns 1 if string found
// returns 0 if string not found
char StrContains(char *str, char *sfind)
  char found = 0;
  char index = 0;
  char len;

  len = strlen(str);

  if (strlen(sfind) > len) {
    return 0;
  while (index < len) {
    if (str[index] == sfind[found]) {
      if (strlen(sfind) == found) {
        return 1;
    else {
      found = 0;

  return 0;

Thanks and regards,


Apr 11, 2014, 10:21 pm Last Edit: Apr 12, 2014, 09:29 am by B83s Reason: 1
I see that req_index is reset to 0 at the end of the loop ... Try to set it at 0 just after the if (client) ... It will be better for understanding the program

Maybe add a '\0' car at the end of the string HTTP_req once all the request has been read ...

You should serial.print the HTTP_req before using it to see what it contains Just after the the line if (c == '\n' && ....)


Thanks thats a good idea!

I didn't find a fix for this issue... instead I searched for another RF library and after implementing the RemoteSwitch from https://github.com/hjgode/homewatch/tree/master/arduino/libraries/RemoteSwitch it worked perfectly fine!

Thanks for the help!


Hi jorgibravo,

Thanks a lot for the link to Randy Simons library. It works great.

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