HC 05 Bluetooth module not communicating via UART

Projects General Guidance
1

my hc 05 Bluetooth module is fine. it connects to phone and enters AT mode. But the sent data to Bluetooth module is not receiving on my serial monitor. help me solve this issue. Also, i have tried both using diff gpio's and baud rate(9600,38400)

#include <SoftwareSerial.h>

// Define RX and TX pins (Use GPIOs that support software serial)
SoftwareSerial hc05(4, 5); // GPIO4 (D2) = RX, GPIO5 (D1) = TX

void setup() {
    Serial.begin(115200);  // Hardware Serial for debugging
   hc05.begin(38400);  // Software Serial for communication
    Serial.println("SoftSerial started!");
}

void loop() {
  // listen for communication from the ESP8266 and then write it to the serial monitor
  if (hc05.available()) {
    Serial.write(hc05.read());
  }

  // listen for user input and send it to the ESP8266
  if (Serial.available() > 0) {
    Serial.println("Writing to hc05...");
    Serial.println(Serial.available());
    Serial.println(Serial.read());
    hc05.write(Serial.read());
  }
}
2

I don't know what you eactly mean with "" and how is the BT module settings, but based on my previous (old, 3 years ago) experiences with HC05 I remember the default baud rate is 9600 not 38400.
This was one of my test sketches, just to check the communication with the phone (with a simple AppInventor app sending 'A' to turn the LED on, or 'a' off), give it a try and report the serial output when sending characters:

#include <SoftwareSerial.h>
/* 
BT module:
RXD <--> Pin 4 (Tx)
TXD <--> Pin 5 (Rx)
VCC <--> 5V
GND <--> GND

Add a LED on pin D3 with 220 Ohm resistor
*/

#define LED 3
SoftwareSerial HC05(4, 5); // TX, RX

void setup ()
{
  Serial.begin(115200);
  HC05.begin(9600);
  pinMode (LED, OUTPUT);
  Serial.println("INIT");
}
void loop ()
{
  if ( HC05.available() ) {
    char c = HC05.read();
    Serial.print(c);
    Serial.println(" received!");
    if (c == 'A') {
      digitalWrite(LED, HIGH);
      Serial.println("ON");
    }
    if (c == 'a') {
      digitalWrite(LED, LOW);
      Serial.println("OFF");
    }
    delay(100);
  }
}
3

Topic moved. Please do not post in "Uncategorized"; see the sticky topics in Uncategorized - Arduino Forum.

4

Since you are attempting to enter AT mode, you use 38400, no exceptions. Nothing you have done, or said, confirms your wiring is correct, so check that it is.

Rx to Tx, and Tx to Rx

5

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.