Control Output using Bluetooth on ESP32

1// This example code is in the Public Domain (or CC0 licensed, at your  option.)
2// By Evandro Copercini - 2018
3//
4// This example creates a bridge  between Serial and Classical Bluetooth (SPP)
5// and also demonstrate that SerialBT  have the same functionalities of a normal Serial
6//
7// The code displays the  received data and controls the on board LED
8//
9// Connect your device to ESP32test
10//  Use Serial Bluetooth Terminal app.
11
12// this library forms part of the ESP32  Boards Manager file
13#include "BluetoothSerial.h"
14
15#if !defined(CONFIG_BT_ENABLED)  || !defined(CONFIG_BLUEDROID_ENABLED)
16#error Bluetooth is not enabled! Please  run `make menuconfig` to and enable it
17#endif
18
19#if !defined(CONFIG_BT_SPP_ENABLED)
20#error  Serial Bluetooth not available or not enabled. It is only available for the ESP32  chip.
21#endif
22
23// set variables and constants
24BluetoothSerial SerialBT;                   // set the Object SerialBT
25String text = "";                           //  define the text variable to receive BT input
26int LED_BUILTIN = 2;                        //  the pin number of the onboard LED
27bool LED_STATE = false;                     //  set the LED Status to False
28
29// set up a number array called BT.
30// The  assigned values are LED_ON = 0, LED_OFF = 1, TOGGLE = 2, UNDEFINED = 3
31enum BT  {LED_ON, LED_OFF, TOGGLE, UNDEFINED };   
32int BT = LED_OFF;                            //  set the enum array to 1
33
34void setup() {
35  Serial.begin(115200);                      //  Serial Monitor
36  SerialBT.begin("ESP32test");               // Bluetooth device  name
37  Serial.println("The device started, now you can pair it with bluetooth!");
38  pinMode(LED_BUILTIN, OUTPUT);              // set up the onboard LED pin as output
39}
40
41void  loop() {
42  // This line sets the output from the PC to the BT device
43  if  (Serial.available()) {SerialBT.write(Serial.read()); }
44
45  // This line sets  the input from the device to the PC
46  if (SerialBT.available() > 0) {
47    //  stripping transfer characters to get the actual text
48    text = SerialBT.readStringUntil('\n');     // get the BT input upto CRLF
49    text.trim();                               //  remove whitespace
50
51    // set the value of BT enum array dependent on the  input text received
52    if (text == "Led On"){ BT = LED_ON; }       // set  BT to 0
53    else if (text == "Led Off"){ BT = LED_OFF; }// set BT to 1
54    else if (text == "Toggle"){ BT = TOGGLE; }  // set BT to 2
55    else { BT  = UNDEFINED; }                    // input not recognised
56    //Serial.println(text);                     // show the received text in the monitor
57
58    // this  switch case statement uses the value of BT to decide which code to run 
59    switch  (BT) {
60      case 0 :                                  // LED_ON
61        LED_STATE  = true;                       // set the variable to true
62        Serial.println("LED  ON");               // print to the Monitor
63        digitalWrite(LED_BUILTIN,  LED_STATE);   // turn on the LED
64        break;                                  //  break out of the switch case statement
65
66      case 1 :                                  //  LED_OFF
67        LED_STATE = false;                      // set the variable to  false
68        Serial.println("LED OFF");              // print to the Monitor
69        digitalWrite(LED_BUILTIN, LED_STATE);   // turn off the LED
70        break;                                  // break out of the switch case statement
71
72      case 2 :                                  // LED_TOGGLE
73        LED_STATE  = !LED_STATE;                 // set the variable. Toggle the previous state
74        Serial.println("TOGGLE LED");           // print to the Monitor
75        digitalWrite(LED_BUILTIN,  LED_STATE);   // toggle the LED
76        break;                                  //  break out of the switch case statement
77
78      case 3:                                   //  UNDEFINED
79        LED_STATE = false;                      // set the variable  to false
80        Serial.println("UNDEFINED INPUT");      // print to the Monitor
81        digitalWrite(LED_BUILTIN, LED_STATE);   // turn off the LED
82        break;                                  // break out of the switch case statement
83
84      default :                                 // if BT is not in the correct range  then this code is executed
85        Serial.println("Unrecognised input received");
86    }
87  }
88  // slight 20ms delay
89  delay(20);
90}
91