Getting started with mbed-OS and mbed Online Compiler

PART 1: PINOUT

##PART 2: INTRODUCE TO MBED-OS

When building an Internet of Things (IoT) system, choosing a platform to design and build a system is very important. ARM Inc is a well-known ARM microcontroller manufacturer, which is widely used in embedded systems and mobile devices. With the advantage of the chip designer, this company provides a complete platform for developing IoT systems, called ARM mbed IoT Device Platform.

Important component of ARM mbed IoT Device Platform is the embedded operating system for ARM Cortex-M microcontrollers, called mbed-OS. It is evaluated as an embedded operating system that is well suited for developing IoT systems with basic features such as: security, multiple interfaces, RTOS, multiple libraries for common types of sensors and peripherals and in particular it is open-source. Let’s take a look at some of the basic features of the mbed OS.

The features and benifits of mbed-OS

###mbed OS Connectivity

Architecture

Typical mbed OS Applications

Useful website for mbed-OS

• https://www.mbed.com/en/platform
• https://www.mbed.com/en/platform/mbed-os/
• https://docs.mbed.com/
• https://developer.mbed.org/
• https://github.com/ARMmbed/mbed-os

##PART 3: PROGRAMMING FOR THE VBLUno51 BOARD USING MBED ONLINE COMPILER

mbed Online Compiler is a compiler for mbed-OS. It works online, you need only a computer with internet connection, you can write code and compile easily for the VBLUno51 board. The following sections presents the steps to using mbed Online Compiler.

Step 1: Register an account on developer.mbed.org

(If you have an account already, you can skip this step)

Access to [https://developer.mbed.org] (https://developer.mbed.org), register an account for developers with mbed OS. It is completely free so you can confidently register.

Step 2: Login

Click Compiler button or access this address https://developer.mbed.org/compiler/

Step 3: Chose Device Platform for application

• Click on the Platform button in the upper right corner of the screen. The Select a Platform window appears, click on Add platform

• You select Nordic NRF51-DK board. This board has configuration quite similar to the VBLUno51 board.

• Next, you choose Add to your mbed compiler

• Click on Compiler button to return to the compiler, the right-hand corner of the browser will display the Nordic NRF51-DK board.

Step 4: Hello World Example

In this step, we are going to make a simple example, with name "vbluno51_blinky”.

• 4.1 Add an existing example to your account

  • Click on “Import a program”,
  • Search by mbed_blinky keywords.
  • In results list, select mbed_blinky example. Click Import button to add this example to your account

You can edit the project name follow below picture.

• 4.2 Modify program source code in the main.cpp file

Copy the following source code to main.cpp file.

/********************************************
VBLUNO51 BOARD
mbed Online Compiler
Project: Blink led and transmit via UART (with HWFC)
Note: select NRF51_DK platform
*********************************************/

#include "mbed.h"

/*For VBLUno51 board*/
#define PIN_TX  p10
#define PIN_RX  p11
#define PIN_RTS p12
#define PIN_CTS p13
#define PIN_LED p7

Serial pc(PIN_TX, PIN_RX); // tx, rx
DigitalOut led(PIN_LED);

int main() {        

	//Init
	pc.baud(115200);
	pc.set_flow_control(SerialBase::RTSCTS, PIN_RTS, PIN_CTS);
	pc.printf("\r\n-------------------------------------\r\n"
	      		"Tests for VNG VBLUno51 board\n\r"              
	      		"-------------------------------------\r\n");   

	//No condition loop
	while(1) {
		led = 1;
		wait(1);
		led = 0;
		wait(1);        
		pc.printf("Finish a period\r\n");
	}
	return 0;
}

Click on the Save button

• 4.3 Press Compile button to compile the program

The result is a successful compilation, creating an executable file (* .hex) and automatically saving it to your computer

• 4.4 Load executable file into VBLUno51 board

After the VBLUno51 board is connected to computer via USB cable, a partition which has name is DAPLINK will be added to your computer. For downloading executable file into VBLUno51 board, you only need to copy this file into the above partition and wait for this progress is done.

• 4.5 Run application

After loading executable file into VBLUno51 board is done, the application will be run automatically. If every thing is success, you will see LED on the VBLUno51 board is lights on and off at 2 second intervals. Using a terminal software such as Hercules or PuTTY to connect to the VBLUno51 board at 115200 baud speed, you will see results as the below image.