> For the complete documentation index, see [llms.txt](https://longer-vision-robot.gitbook.io/arduino-full-stack/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://longer-vision-robot.gitbook.io/arduino-full-stack/14_communication/03_bluetooth.md).
# 14.3 Bluetooth
A **ZS-040** (detected as **HC-0X**) bluetooth module is provided in our Arduino course on-site, which looks like:
The **ONLY** difference is that the provided bluetooth module has 4 pins but **NOT** 6 pins, without pin **STATE** and pin **EN**.
## Hardware Wiring
## Sketch
The code can be found at [Examples\_Arduino - arduinocc - \_003\_Bluetooth - \_003\_Bluetooth.ino](https://github.com/LongerVisionRobot/Examples_Arduino/blob/master/howtomechatronics/_003_Bluetooth/_003_Bluetooth.ino) You can also refer to Adafruit's official website at .
```
#include
#define ledPin 7
SoftwareSerial mySerial(10, 11); // RX, TX
int state = 0;
void setup() {
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, HIGH);
Serial.begin(38400); // Default communication rate of the Bluetooth module
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
Serial.println("Goodnight moon!");
// set the data rate for the SoftwareSerial port
mySerial.begin(9600);
//mySerial.println("Hello, world?");
}
void loop() {
if(mySerial.available() > 0){ // Checks whether data is coming from the serial port
state = mySerial.read(); // Reads the data from the serial port
Serial.print("mySerial available!\n");
}
if (state == '0') {
digitalWrite(ledPin, LOW); // Turn LED OFF
Serial.println("LED: OFF"); // Send back, to the phone, the String "LED: ON"
state = 0;
}
else if (state == '1') {
digitalWrite(ledPin, HIGH);
Serial.println("LED: ON");;
state = 0;
}
}
```
**Note: Please remove your bluetooth module before flashing your code onto Arduino board. Otherwise, you'll obtain the following ERROR messages:**
## Mobile APPs
### Arduino Bluetooth Tutorial Example Android App
This APP can be downloaded from
After the installation, by click on **Connect** on the **FIRST** page of this APP, you'll see all detected bluetooth devices as:
By selecting one of the devices, you'll see the device is NOW **connected**.
By clicking **Turn ON** and **Turn OFF**, you will see the led can be light on and off accordingly.
And, some serial message will be printed on the **Monitor Serial** dialog as:
### Longer Vision Robot LVControl
[Longer Vision Robot](http://www.longervisionrobot.com) provides its own APP **LVContrl**, which can be downloaded from ...
The first page of **LVContrl** looks like:
By selecting page **BTSet**, we can easily **SEARCH FOR VISIBLE DEVICES**:
After simply pair the device by just clicking on the listed device name, you will be able to see that our bluetooth device is now listed in **LIST PAIRED DEVICES**.
## Assignment:
Two other very similar reference examples can be found at:
*
*
， which are left for students as their assignments.