Control a blinking light with a master and slave HC-05

Projects Programming
1

I am trying to make a project with a master and slave HC-05 module. Right now I'm just trying to make sure that it works and is connected properly. I have written this code for the master module:

#include <SoftwareSerial.h>

SoftwareSerial serial(2,3);

void setup() {
  // put your setup code here, to run once:
  serial.begin(38400);

}

void loop() {
  // put your main code here, to run repeatedly:
  serial.write('1');
  delay(1000);
  serial.write('0');
  delay(1000);
  
}

and this for the slave module:

#include <SoftwareSerial.h>

SoftwareSerial serial(2,3);
int led = 8;
int data;

void setup() {
  // put your setup code here, to run once:
  serial.begin(38400);
  pinMode(led, OUTPUT);

}

void loop() {
  if (serial.available() > 0) {
    data = serial.read();
  }

  if (data == "1") {
    digitalWrite(led, HIGH);
  }
  
  else if (data == "0") {
    digitalWrite(led, LOW);
  }
  
}

I have been reading the SerialSoftware documentation, and I believe that the master code should simply send a 1, wait a second, send a 0, and then wait a second. And the slave should be receiving this data, turning on the LED, waiting a second, then turning it off. I see the synchronized blinking lights so I believe that my HC-05s are connected, and I paired the successfully. It may be something I did wrong with the wiring? On both of them, RX of the HC-05 is connected to pin 2 and TX is connected to pin 3. And on the slave I simply have pin 8 connected to an led. When I plug in both arduinos and upload the sketches, the LED doesn't do anything. Is there a way I can make sure data is being transmitted? Did I do something wrong in my code to make it not work? Thanks for any help!

2

Try

if (data == '1') {

I'm a little surprised you didn't get a compilation error

3

You can write a simple loopback sketch to re-transmit any characters that are received. If that works, you can try the LED code.

4

You may want to limit your changes to when data comes in.

void loop() {
   if (serial.available() > 0) {
      data = serial.read();
      if (data == '1') {
         digitalWrite(led, HIGH);
      } else if (data == '0') {
         digitalWrite(led, LOW);
      }
   }
}

-jim lee

5

I have tried changing the double quotes to single quotes, as well as moving the if statement to right after we read the data and neither fix the problem. I did quickly just write the LED pin on with the slave module, and the pin turned on as expected. How can I make sure serial data is being sent or received?

6

Why in the world would you name you SoftwareSerial instances "serial"? That's one capitalization mistake away from the standard Arduino "Serial" object. Seems like a very confusing mistake waiting to happen.

7

ithortureu:
How can I make sure serial data is being sent or received?

reply #2

8

Aarg, how would I go about doing that? It sounds like what I wan to do but I'm not sure how. Could you link me to a reference or something? Thanks!