Issues using HC-06 Bluetooth module with arduino

Question

I recently ordered an HC-06 Bluetooth module for my Arduino Uno, and after watching this video, and many others, I still have been having many issues figuring out how to get it to work, and some questions for how the code receives and reads serial data from my phone.

1. I assume this wiring is correct, right?

   • Rx> Tx
   • Tx> Rx
   • Gnd> Gnd
   • Vcc> 3.3V

2. When I sent a command over the Bluetooth terminal app I have, the serial monitor displays that command over and over, I assume that is correct also?

3. How do I read the serial input? I've been using

   if(Serial.available() > 0)
    phoneInput = (char) Serial.read();
   

   and then displaying the value of phoneInput to the serial monitor, but for some reason I can't seem to have it control anything properly (in this case an LED)

4. What datatype is the Serial.read() returning to my variable before I cast char on to it?

5. I get errors uploading the code to the board (avrdude: stk500_recv(): programmer is not responding), until I remove the pin connected to the Rx on the arduino, is there a cleaner solution to uploading the board without unplugging wires?

• Nguyen Van Quoc: I had follow this tutorial and problem fixed: Tutorial Configure HC-06 Bluetooth Module using AT Command

Answer 1

I assume this wiring is correct, right?

Rx > Tx
Tx > Rx
Gnd > Gnd
Vcc > 3.3V

Almost. The Arduino's TX should be reduced to 3.3V using a 10k/20k potential divider.

How do I read the serial input? I've been using

if(Serial.available() > 0)
 phoneInput = (char) Serial.read();

You should read and digest this.

What datatype is the Serial.read() returning to my variable before I cast char on to it?

An integer. It holds either 0-255 representing the ASCII code for a character, or -1 if there is nothing in the buffer to read.

I get errors uploading the code to the board (avrdude: stk500_recv(): programmer is not responding), until I remove the pin connected to the Rx on the arduino, is there a cleaner solution to uploading the board without unplugging wires?

That will be because you are using pins 0/1 to communicate with the bluetooth which you can't do because those are used to communicate with the PC.

• Zelkins: I'm away from my computer so I can't test your answers, but thanks so much, your answers were super helpful, but I do have one question; If I shouldn't use pins 0 and 1 as Rx and Tx, what pins should I use?
• Majenko: Anything else - I assume you're using SoftwareSerial - that library is designed to use any pin except 0/1. You use Serial for pins 0/1. There seems to be a number of tutorials (videos?) around that show SoftwareSerial being incorrectly used with pins 0/1.