{"id":1599,"date":"2019-06-05T15:08:43","date_gmt":"2019-06-05T07:08:43","guid":{"rendered":"https:\/\/www.techcoil.com\/blog\/?p=1599"},"modified":"2020-05-12T10:52:21","modified_gmt":"2020-05-12T02:52:21","slug":"how-to-write-a-c-program-to-communicate-with-an-esp32-development-board-via-bluetooth-serial","status":"publish","type":"post","link":"https:\/\/www.techcoil.com\/blog\/how-to-write-a-c-program-to-communicate-with-an-esp32-development-board-via-bluetooth-serial\/","title":{"rendered":"How to write a C# program to communicate with an ESP32 development board via Bluetooth Serial"},"content":{"rendered":"

Coupled with Bluetooth Serial and GPIO pins, ESP32<\/a> can augment a Windows machine<\/a> with the ability to read from sensors. <\/p>\n

So with an ESP32 development board<\/a>, you can turn your old Windows machine into an IOT gateway<\/a> that can sense its operating environment.<\/p>\n

Given these points, let us look at how we can write a C# program to communicate with an ESP32 development board via Bluetooth Serial.<\/p>\n

Getting your ESP32 development board to communicate with another device over Bluetooth Serial<\/h2>\n

In order to follow this tutorial, upload the following Arduino Sketch onto your ESP32 development board: <\/p>\n

\r\n#include "BluetoothSerial.h"\r\n   \r\nBluetoothSerial SerialBT;\r\n    \r\nvoid setup()\r\n{\r\n  SerialBT.begin("ESP32test");\r\n  delay(1000);\r\n}\r\n    \r\nvoid loop()\r\n{\r\n  String inputFromOtherSide;\r\n  if (SerialBT.available()) {\r\n    inputFromOtherSide = SerialBT.readString();\r\n    SerialBT.println("You had entered: ");\r\n    SerialBT.println(inputFromOtherSide);\r\n  }\r\n}\r\n<\/pre>\n
As I had mentioned in the guide on how to get your ESP32 development board to communicate with another device over Bluetooth Serial<\/a>, this Arduino Sketch will echo back whatever message that it receives from its Bluetooth connection.<\/p>\n
Connecting your ESP32 development board via Bluetooth on Windows 10<\/h2>\n
After you had uploaded the Arduino Sketch onto your ESP development board, place it near to your Windows machine.<\/p>\n
Given that, your Windows 10 machine should be able to detect your ESP32 development board as a Bluetooth device. <\/p>\n
In order for the C# program to communicate with your ESP32 board, pair your ESP32 board with Windows<\/a>.<\/p>\n
As mentioned in the post, find the COM port that is labelled as Outgoing<\/strong> as its communication Direction<\/strong>. <\/p>\n
For example, you should use COM4<\/strong> in your C# program if you have the following Bluetooth Settings window screen:<\/p>\n
\"Bluetooth<\/p>\n
Writing the C# program to communicate with your ESP32 development board via Bluetooth Serial<\/h2>\n
Once you had established the Bluetooth connection between your ESP32 development board and Windows 10, it is time to write the C# program. <\/p>\n
Since Windows had created the COM ports for you, the C# program can use the same libraries that I had mentioned in how to use C# to read sensor data from Arduino or ESPx via serial connection<\/a>.<\/p>\n
With this in mind, the following C# program gets two echo messages from your ESP32 development board and display them onto the console:<\/p>\n
\r\nusing System;\r\nusing System.IO.Ports;\r\n\r\nnamespace Communicate_With_ESP32_via_Bluetooth_Serial\r\n{\r\n    class MainClass\r\n    {\r\n        public static void Main(string[] args)\r\n        {\r\n            try\r\n            {\r\n                SerialPort port = new SerialPort();\r\n                port.BaudRate = 9600;\r\n                port.PortName = "COM4";\r\n                port.Open();\r\n\r\n                try\r\n                {\r\n                    port.Write("Hi, I am trying to talk to you.");\r\n                    Console.WriteLine(port.ReadLine());\r\n                    Console.WriteLine(port.ReadLine());\r\n\r\n                    port.Write("Why do you have to repeat what I say?");\r\n                    Console.WriteLine(port.ReadLine());\r\n                    Console.WriteLine(port.ReadLine());\r\n                }\r\n                catch (Exception ex)\r\n                {\r\n                    Console.WriteLine("Encountered error while writing to \/ or reading from serial port");\r\n                    Console.WriteLine(ex.ToString());\r\n                }\r\n\r\n            }\r\n            catch (Exception ex)\r\n            {\r\n                Console.WriteLine("Encountered error while opening serial port");\r\n                Console.WriteLine(ex.ToString());\r\n            }\r\n        }\r\n    }\r\n}\r\n<\/pre>\n
When you run the above program, you should get output similar to the following:<\/p>\n
\"Command<\/p>\n
Understanding the C# code for communicating with our program running on the ESP32 development board<\/h2>\n
First of all, we indicate that we wish to use some classes contained in the System and System.IO.Ports namespaces:<\/p>\n
\r\nusing System;\r\nusing System.IO.Ports;\r\n<\/pre>\n
Once we had done so, we define our own namespace and a class with a Main method.<\/p>\n
Inside the Main method, we try to create a SerialPort<\/a> instance to COM4 with a baud rate of 9600. When we had done so, we attempt to open the connection to our serial port:<\/p>\n
\r\nSerialPort port = new SerialPort();\r\nport.BaudRate = 9600;\r\nport.PortName = "COM4";\r\nport.Open();\r\n<\/pre>\n
After that, we are ready to communicate with the program running on our ESP32 development board:<\/p>\n
\r\nport.Write("Hi, I am trying to talk to you.");\r\nConsole.WriteLine(port.ReadLine());\r\nConsole.WriteLine(port.ReadLine());\r\n \r\nport.Write("Why do you have to repeat what I say?");\r\nConsole.WriteLine(port.ReadLine());\r\nConsole.WriteLine(port.ReadLine());\r\n<\/pre>\n
As an illustration, our C# program send two lines of string to the ESP32 program using SerialPort.Write<\/code><\/a>.<\/p>\n
Since we know that the ESP32 program will return us two lines<\/strong> of string for every line it receives, we use SerialPort.Read<\/code><\/a> twice<\/strong> right after<\/strong> we send one line of string. In addition to that, we directly output what we read with SerialPort.Read<\/code> to the console. <\/p>\n
Further extensions<\/h2>\n
At this point in time, you should be able to create a C# program that can communicate with an ESP32 program via Bluetooth Serial.<\/p>\n
If you have some sensors<\/a> to play with, you should be able to connect them to your ESP32 board and extend the C# program to get some sensor readings via your ESP32 board.  <\/p>\n
In case you need it, here some some ESP32 tutorials that you can refer for sensing the real world:<\/p>\n