BLUETOOTH INTERFACING WITH NODEMCU
In this experiment, we are going to interface HC-05 Bluetooth module with NodeMCU which has ESP8266 microcontroller. For wireless communication, a Bluetooth module is used and we will get messages through Bluetooth terminal app which should be installed in our smartphones.
Synopsis

In this experiment, we are going to interface HC-05 Bluetooth module with NodeMCU which has ESP8266 microcontroller. For wireless communication, a Bluetooth module is used and we will get messages through Bluetooth terminal app which should be installed in our smartphones.

Description


HC-05 Bluetooth module

• HC-05 Bluetooth module is used for wireless communication only for small distances.

• This Bluetooth module will have connected to only Bluetooth enabled devices like smartphones, laptops etc….

• HC-05 Bluetooth module has 2 modes are master and slave means that it give request for pairing as well as it accepts pairing

HC-05 Bluetooth specifications:

• Its default pin code. “1234” or “0000” for pairing with device

• Vcc and GND pins are used for powering the HC-05.

• Tx and Rx pins are used for communicating with the microcontroller.

• KEY pin for activating the HC-05 module. when it is low, the module will disable

• State pin acts status indicator. whether the Bluetooth module and device are properly paired. When pairing is done led will glow.

NodeMCU

A NodeMCU is a development board with an inbuilt Wi-Fi module in it. It is a basic and a cheapest board to carry out projects using the internet of things. The NodeMCU has ESP8266 microcontroller unit in it. The operation of this microcontroller is controlled with the programs used in Arduino thus making it very easier to use and also to learn basic IoT projects. This board has inbuilt 2.4GHz antenna to receive Wi-Fi functions. This board has a memory of 4mb to store the data acting as ROM and 64Kb of RAM. This board operates at 3.3 volts and 5v and it is mandatory to operate the board at these voltage levels and if voltage is more than that it will board may damage few GPIO pins (general input-output pins).


Pin Configuration of NodeMCU

1. Vin: 3.3V can be provided at this pin as the supply to power on the board. This pin is used to power on the entire microcontroller.

2. GND: This pin is connected to the negative terminal of the battery.

3. RST: This pin resets the microcontroller and clears the memory.

4. EN: This pin is used to enable the operation of microcontroller.

5. 3V3: This pin provides 3V output and this can be used to power up some sensor units connected to the microcontroller.

6. SD1, CMD, SD0, CLK: These pins are used in SPI communication, that is it is used to transfer the signals between two microcontrollers, Rx and Tx modules with asynchronous transmission.

7. SD3, SD2: These pins can also function as asynchronous transmission or as GPIO pins.

8. RSV: These are two reserved pins used by the microcontroller and cannot be used in connecting any external circuits to it.

9. A0: This microcontroller only has one analog pin for Analog communication. This A0 pin is used in analog signal communication.

10. GPIO 1 – 16: This controller board has 16 input-output pins which be used as input or output pin based on the programming.

11. GP10 1, 3, 13, 15: This microcontroller has 2 UART communication pins, RX0, TX0 (GPIO 1 & GPIO 3) and RX1, TX1 (GPIO 13, GPIO15).

HC-05 Bluetooth and NodeMCU pin connections


Schematic


Code

int ANALOG_PIN = A0;

void setup() {
  pinMode(ANALOG_PIN,INPUT);  // SET A0 PIN AS INPUT MODE
  Serial.begin(9600);         // 9600 BITS TRANFERING TO PC PER SECOND
}
void loop() {
 int ANALOG_VAL = analogRead(ANALOG_PIN); // READING THE VAULES FROM ANALOG PIN
 Serial.println(ANALOG_VAL);  // SENDING POT-VAULES THROUGH UART PINS TX,RX
 delay(2000);
}

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