{"id":9920,"date":"2022-06-20T09:45:22","date_gmt":"2022-06-20T09:45:22","guid":{"rendered":"http:\/\/fastbitlab.com\/?p=9920"},"modified":"2023-08-04T09:36:00","modified_gmt":"2023-08-04T04:06:00","slug":"microcontroller-embedded-c-programming-lecture-48-embedded-hello-world","status":"publish","type":"post","link":"https:\/\/fastbitlab.com\/blog\/microcontroller-embedded-c-programming-lecture-48-embedded-hello-world\/","title":{"rendered":"Microcontroller Embedded C Programming Lecture 48 | Embedded – ‘Hello World’"},"content":{"rendered":"
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Embedded – ‘Hello World’<\/strong><\/span><\/h1>\n
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In this lecture, let’s write a ‘Hello World’ program for our embedded board based on the ARM Cortex M4 processor.<\/span><\/p>\n

Now we’ll start a new STM32 project. To create a new STM32 project, go to file, go to new, and click on STM32 project, as shown in Figure 1. <\/span><\/p>\n

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Figure 1. Creating a new STM32 Project<\/span><\/figcaption><\/figure>\n

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After that, select the STM32F4DISCOVERY option, and click on Next, as shown in Figure 2.<\/span> <\/span><\/p>\n

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Figure 2. Target selection<\/span><\/figcaption><\/figure>\n

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Now you have to give a name for your project. Let me give a 001HelloWorld. After that, the targeted language is ‘C,’ the Targeted Binary type is Executable here, and the targeted project type is select Empty, and after click Finish, as shown in Figure 3.<\/span><\/p>\n

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Figure 3. Project setup<\/span><\/figcaption><\/figure>\n

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We just created an empty 001HelloWorld project, so it has added a couple of folders here\u2014the <\/span>Inc<\/b> folder or include folder, where we keep all our header files of our project. And the source(Src) folder so where we keep all our source codes that is <\/span>.c <\/b>files. And here, we can see that the IDE has already added three files: main.c, syscalls.c, sysmem.c.<\/span><\/span><\/p>\n

After that, the important thing here is the startup code for the microcontroller. So, before working with any microcontroller, it doesn’t matter whether it is from ST, or whether it is from TI, or prescale, or whatever it is. So, you should have a startup code for that microcontroller in your project. That is very very important, and so for this article, we are not going to explore the startup code because that would be too early to explore. But, in later sections, I have a plan to introduce writing startup files from scratch.<\/span><\/p>\n

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Figure 4. 001 HelloWorld Project<\/span><\/figcaption><\/figure>\n

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So, we’ll see that later when we understand more about the microcontroller and the Embedded ‘C’ concept. <\/span><\/p>\n

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The main thing here that you should observe is that it has added the main source file where we will write our code for the microcontroller.<\/span><\/p>\n

Now, let’s write a program to print the “Hello World” message. For that, let’s use the standard library function <\/span>printf<\/b>. Let me write <\/span>printf(“Hello World\\n”);<\/b> And since it is a standard library function, I write<\/span> #include<stdio.h> <\/b><\/span><\/p>\n

\/**<\/span>\r\n******************************************************************************<\/span>\r\n* @file main.c<\/span>\r\n* @author Auto-generated by STM32CubeIDE<\/span>\r\n* @version V1.0<\/span>\r\n* @brief Default main function.<\/span>\r\n******************************************************************************<\/span>\r\n*\/<\/span>\r\n\r\n#include<\/span><stdio.h><\/span>\r\nint<\/span> main(void<\/span>)\r\n{\r\nprintf<\/span>(\"Hello World\\n<\/span>\");\r\n\r\nfor(;;);<\/span>\r\n}<\/pre>\n
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Now you may wonder how this printf would work because we don’t have any display or standard output device which is connected to our embedded board. So, we don’t have any monitor, or we don’t have an LCD, which is connected to our embedded board. <\/span><\/p>\n
How are we going to see the message output without a display device connected to our board? <\/span><\/p>\n
For that, there is one solution, and that solution comes from the ARM Cortex Processor itself. Let’s explore that. <\/span><\/p>\n
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Using printf outputs on ARM Cortex M3\/M4\/M7 based MCUs<\/strong><\/span><\/p>\n