Help needed with browser switch project with nrf24l01 and servo

Hi, I am a beginner to electronics and I am trying to make an arduino project which allows me to activate a servo motor by a browser switch. Adding to the complexity, the ethernet module and the servo motor are of separate arduino units, linked via the RF module, nrf24l01.

Currently, the recieving node does not seem to recieve the transmission as servo motor fails to activate. Additionally, successful transmission is not seen over the serial monitor of the IDE. I think I have some difficulties with interfacing the browser switch on the ethernet unit to trigger the transmission of data to the recieving unit. I appreciate if I could get some advice on correcting it.

Transmitting unit

#include <SPI.h>

#include "RF24.h"

#include <Ethernet2.h>

int msg[1];

RF24 radio(9,10);

const uint64_t pipe = 0xE8E8F0F0E1LL;

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

byte ip[] = { 192,168,1,101 };

const int MAX_PAGENAME_LEN = 8; // max characters in page name

char buffer[MAX_PAGENAME_LEN+1]; // additional character for terminating null

EthernetServer server(232);

void setup()

{

Serial.begin(9600); //Start serial port for debugging

radio.begin();

radio.openWritingPipe(pipe);

Ethernet.begin(mac, ip);

server.begin();

delay(2000);

}

void loop()

{

EthernetClient client = server.available();

if (client) {

int type = 0;

while (client.connected()) {

if (client.available()) {

// GET, POST, or HEAD

memset(buffer,0, sizeof(buffer)); // clear the buffer

if(client.readBytesUntil('/', buffer,sizeof(buffer))){

if(strcmp(buffer,"POST ") == 0){

client.find("\n\r"); // skip to the body

// find string starting with "pin", stop on first blank line

// the POST parameters expected in the form pinDx=Y

// where x is the pin number and Y is 0 for LOW and 1 for HIGH

while(client.findUntil("pinD", "\n\r")){

int pin = client.parseInt(); // the pin number

int val = client.parseInt(); // 0 or 1

pinMode(pin, OUTPUT);

if(pin == 1){

msg[0] = 111; //Send the 111 to the reciever

radio.write(msg, 1); }

}

sendHeader(client,"Post example");

//Control of Servo

client.print(

"<form action='/' method='POST'><p><input type='hidden' name='pinD7'");

client.println(" value='1'><input type='submit' value='Servo Right'/></form>");

client.println("</body></html>");

client.stop();

}

// give the web browser time to receive the data

delay(1);

client.stop();

}

void sendHeader(EthernetClient client, char *title)

{

// send a standard http response header

client.println("HTTP/1.1 200 OK");

client.println("Content-Type: text/html");

client.println();

client.print("<html><head><title>");

client.print(title);

client.println("</title><body>");

}

Recieving unit

#include <SPI.h>

#include <Servo.h>

#include "nRF24L01.h"

#include "RF24.h"

Servo myservo; // create servo object to control a servo

int msg[1];

RF24 radio(9,10); // NRF24L01 Pin

const uint64_t pipe = 0xE8E8F0F0E1LL; //Start Pipe Communication Address

void setup(void){

Serial.begin(9600);

myservo.attach(3);

radio.begin();

radio.openReadingPipe(1,pipe);

radio.startListening();

}

void loop(void){

if (radio.available()){

bool done = false;

while (!done){

done = radio.read(msg, 1);

Serial.println(msg[0]);

if (msg[0] == 111)

{myservo.write(90);}

else

delay(10);}}

else{Serial.println("Error: No Radio Transmission");}}

shabaz over 9 years ago

Hi Thomas,

You have created a serial interface for debugging, but not used it.
If you think the problem is in the transmission unit code then you can use the serial interface to pass debug information to understand
where the code execution has reached and the value of key variables to see where the code begins to deviate from expected behaviour.
Sometimes even an LED can be useful to understand code flow, but you've got a serial interface you could be using.,

The demo examples from the Ethernet2 library contain Serial debug, so you can see from those how to go about this.
https://github.com/adafruit/Ethernet2/blob/master/examples/WebServer/WebServer.ino
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Former Member over 9 years ago in reply to shabaz

Thanks for the advice. I have modified codes of both the transmitting and recieving units since. To better determine the cause of the issue, I've also changed the output of the recieving unit to a blinking LED instead of a servo. I've ran a serial debug of the transmitting unit and it appears that the recieving unit is able to sent the data as seen by the serial input 'Sent' when the web browser button is clicked on. However, the recieving unit does not seem to recieve the data. Again, I ran the serial debug on this end and it seems that it stops at the point when the radio coding interface kicks in. Can anyone help me identify the error in my code?

Transmitting unit
#include <SPI.h>
#include "RF24.h"
#include <Ethernet2.h>

int msg[1];
RF24 radio(9,10);

const uint64_t pipe = 0xE8E8F0F0E1LL;

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192,168,1,101 };

const int MAX_PAGENAME_LEN = 8; // max characters in page name
char buffer[MAX_PAGENAME_LEN+1]; // additional character for terminating null

EthernetServer server(232);

void setup()
{
Serial.begin(9600); //Start serial port for debugging
radio.begin();
radio.openWritingPipe(pipe);
Ethernet.begin(mac, ip);
server.begin();
delay(2000);
}

void loop()
{
EthernetClient client = server.available();

if (client) {

    int type = 0;

    while (client.connected()) {

        if (client.available()) {
        // GET, POST, or HEAD
        memset(buffer,0, sizeof(buffer)); // clear the buffer
        if(client.readBytesUntil('/', buffer,sizeof(buffer))){
          if(strcmp(buffer,"POST ") == 0){
            client.find("\n\r"); // skip to the body
            // find string starting with "pin", stop on first blank line
            // the POST parameters expected in the form pinDx=Y
            // where x is the pin number and Y is 0 for LOW and 1 for HIGH
            while(client.findUntil("pinD", "\n\r")){
              int pin = client.parseInt();       // the pin number
              int val = client.parseInt();       // 0 or 1
              pinMode(pin, OUTPUT);
              Serial.println(pin);
              Serial.println(OUTPUT);
              if (OUTPUT == 1) {
              msg[0] = 111; //Send the 111 to the reciever
              radio.write(msg, 1);
              Serial.println("Sent"); //This works
              }
          }


          }
          sendHeader(client,"Post example");

          //Control of Servo
          client.print(
          "<form action='/' method='POST'><p><input type='hidden' name='pinD7'");
          client.println(" value='1'><input type='submit' value='Servo Right'/></form>");



          client.println("</body></html>");



          client.stop();
        }
      }
    }
    // give the web browser time to receive the data
    delay(1);
    client.stop();
}
}

void sendHeader(EthernetClient client, char *title)
{
// send a standard http response header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println();
client.print("<html><head><title>");
client.print(title);
client.println("</title><body>");
}

Recieving unit
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

int msg[1];
RF24 radio(9,10); // NRF24L01 Pin
const uint64_t pipe = 0xE8E8F0F0E1LL; //Start Pipe Communication Address
int led=3;

void setup()
{
Serial.begin(9600);
radio.begin();
radio.openReadingPipe(1,pipe);
radio.startListening();
pinMode(led, OUTPUT);
}

void loop(void){
   Serial.println("Hello"); //Successful serial print stops at this point until serial error message at the end
if (radio.available()){
   bool done = false;
   while (!done){
     done = radio.read(msg, 1);
     Serial.println(msg[0]);
     if (msg[0] == 111)
     {digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
      Serial.println("Data recieved");
      delay(3000);              // wait for a second
      digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
       delay(1000);              // wait for a second
      }
     else
     delay(10);}}
else{Serial.println("Error: No Radio Transmission");}}
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