Wireless Communication Between Two Arduino Board Using HC-05 Module
In this post I will show you how you can communicate between two Arduino Boards using HC-05 Module. I am using Arduino IDE's version 1.8.7. There are now newer modules that use a 3.0-20170601 firmware due to which module gives an error, But I will show you how you can fix this error. Just follow the exact same steps listed below and you will not get any error.
Material Required-:
- PCB Board
- Arduino Uno x 2
- Led
- Bluetooth Module(HC-05) x 2
- Push Button (Switch)
- Resistor (1k ohm)
- Jumper Wire
Connection for AT Mode -:
- 5V to Arduino 5V
- GND to Arduino GND
- TX to Arduino TX(D1)
- RX to Arduino RX(D0)
- Enable Pin to 5V
 |
| Connections for AT Command Mode |
Step-1:
- Upload Blank code on Arduino Board.
Step-2:
- While connecting supply to module long press the "Key Button" situated above enable pin.
- Now, You will see a delay in flashing of HC-05 led, that's means you are successfully entered in AT Command Mode.
Step-3:
- Now open serial monitor .
- Remember that HC-05 requires Both "NL and CR" to be set and Baud rate should be on 38400
- Now type "AT" without qoutes , you should get reply OK, it means yor are in AT Command Mode.
Step-4:
- Type "AT+ROLE=0" as it is without quotes, this will set HC-05 on Slave Mode.
- Now, Type "AT+ADDR?" as it is without quotes, this willl give you Module's address note it down somewhere.
- This is all you have to do to set HC-05 on Slave Mode.
Step-5:
- Connect other Module same as previous one.
- Type "AT" to confirm that you are in AT Command Mode.
- Now, Type "AT+ROLE=1" without quotes this will set this module to Master Mode.
- Then, Type "AT+CMODE=0" this will set the connect mode to the fixed address.
- Then,Type "AT+BIND=your_slave's_address", ( Paste the Slave's address you have noted earlier , Address should be in the pattern of 4,2,6 like this->FCA8,9A,00034)
Note-> If the address is not in 4,2,6 pattern make it by adding zeros in start, and use commas instead of colan.
Step-6:
- Now you have successfully set both module.
- Now detach everything and power both module. They will automatically connect to each other
- You will see a sync in flashing of led with a delay of 2seconds.
- Now, it's time to test it.
Connections of Master Module-:
- 5V to Arduino 5V
- GND to Arduino GND
- RX to Arduino TX
- TX to Arduino RX
- Button to Digital Pin 2
- Button to GND
 |
| Master Connection |
Connection of Slave Module-:
- 5V to Arduino 5V
- GND to Arduino GND
- RX to Arduino TX
- TX to Arduino RX
- Led(+ terminal) to Digital Pin 2
- Led (- terminal) to Arduino GND
 |
| Slave Connection |
=== MASTER CODE ===
#define button 2
int value = 0;
void setup() {
Serial.begin(9600);
pinMode(button, INPUT_PULLUP);
}
void loop() {
int val = digitalRead(button);
if (val == 0 && value == 0)
{
Serial.println("1");
value = 1;
delay(200);
}
else if (val == 0 && value == 1)
{
Serial.println("0");
value = 0;
delay(200);
}
delay(200);
}
=== SLAVE CODE ===
#define led 2
void setup() {
Serial.begin(9600);
pinMode(led, OUTPUT);
}
void loop() {
if (Serial.available())
{
char val = Serial.read();
Serial.println(val);
if (val == '1')
{
digitalWrite(led, HIGH);
}
else if (val == '0')
{
digitalWrite(led, LOW);
}
}
}
Note-:
- While Uploading the code to Arduino disconnect the RX and TX pin.
- We can also use "AT+CMODE=1" but this is not recommended because of security reason.
Some AT Commands-:
- AT+NAME (Show name of module)
- AT+PSWD (Show password of module)
- AT+UART (Show default baud rate)
- AT+VERSION (Show version of module)
For any queries contact me on -: tombriddle28@gmail.com
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