I can send on software serial, but not read?

Question

I've been cracking my head over this for a long while.

Like many before me, I'm trying to send and receive data from a HM-10 bluetooth module, arduino mega adk and the app called BLE Scanner. I've figured out receiving alright. Whatever I write into the serial monitor, shows up on the app. Whatever I write into the software serial, shows up. However, I haven't figured out how to read from the software serial. The available function never gets triggered, and always printing out the software serial read is always -1

The app supports sending data over bluetooth as well. However, using:

    #include <SoftwareSerial.h>
SoftwareSerial blueSerial(14, 15); //RX, TX
  blueSerial.begin(9600);
  Serial.begin(9600);
while (1)
  {
    blueSerial.listen();
    if (Serial.available()) {
      Serial.println("Writing");
      blueSerial.write(Serial.read());
      Serial.println(Serial.read());
      Serial.println(blueSerial.available());
    }
    if (blueSerial.available()) {
      Serial.println("Blueserial writing");
      Serial.write(blueSerial.read());
    }
}

The listen function is used out of pure desperation.

How do I fix this? This should be working right? Since I want to be sending AT commands to the bluetooth modules at some time and read their output, getting this to work is really important.

Answer 1

Possibly the built-in UART (Hardware Serial) assigned to the same pins is interfering with SoftwareSerial? If you really want to us SoftwareSerial, try it on a pair of pins that has no hardware UART attached.

And/or try SoftwareSerial (again, on a non-UART pair of pins) to connect to your PC (after uploading; you can't upload with it), and use Serial1 to connect to your device. This isn't the recommended or easiest way but it might help debug the problems you're seeing.

Answer 2

On Mega you don't need to use SoftwareSerial. Mega has 4 Serials. Connect the module to RX3/TX3 like on the Fritzing in your question and use Serial3 in sketch.

void setup() {
  Serial.begin(9600);
  Serial3.begin(8600);
}

void loop() {

  while (Serial.available()) {
    Serial3.write(Serial.read());
  }
  while (Serial3.available()) {
    Serial.write(Serial3.read());
  }
}

Answer 3

If SoftwareSerial is not working then simply do not use it.

You shouldn't be using it anyway.

You have a Mega with 4 UARTs. You are using a pair of the UART pins, and yet you are using SoftwareSerial.

Don't.

instead use the SerialX object (where X is the number by the TX and RX for the pins) to communicate.

SoftwareSerial is only for those times when you don't have enough hardware UARTs, and you have plenty.