01 Read the following program: #include <stdio.h> main() { int i,j, m=55; for(i=1;i<=3;i++) for(j=3; j<=i; j++) m=m%j; printf(“%d\n “, m); } The output of the program is A) 0 B) 1 C) 2 D) 3 Answer: B Explanation: Brief 02 Read the following program: main() { int a=5,b=4,c=3,d=2; if(a>b>c) printf(“%d\n”,d); else if((c-1>=d)==1) printf(“%d\n”,d+1); else printf(“%d\n”,d+2); … Read more
01 Read the following program: main() { int a=1, b=3, c=5; int *p1=&a, *p2=&b, *p3=&c; *p3=*p1*(*p2); printf(“%d\n”,c); } The output result after execution is A) 1 B) 2 C) 3 D) 4 Answer: C Analysis: Brief 02 To write a good program, it is essential to ensure its correctness and reliability, and also to emphasize … Read more
First Encounter with bareboxHey, I’ve been experimenting with embedded booting recently, and I was captivated by a project called barebox. It is not just a simple follower of U-Boot; it inherits the spirit of U-Boot while also drawing on the design philosophy of the Linux kernel. Written in C and managed with kbuild/Kconfig for configuration, … Read more
Scan to FollowLearn Embedded Systems Together, learn and grow together Overview 1.1 What is the SWD Protocol SWD (Serial Wire Debug) is a two-wire debugging interface protocol developed by ARM, specifically designed for debugging and programming Cortex-M series microcontrollers. As a replacement for the traditional JTAG interface, SWD significantly reduces the number of pins while … Read more
Using Overlays in Buildroot Introduction In the article “Automatic Mounting of USB Hard Drives,” I completed debugging by modifying <span>/usr/lib/udev/rules.d/usbmount.rules</span>. During the debugging process, I operated on the development board. After debugging, how can I synchronize the modifications to the SDK code? To address this issue, I first searched the SDK and found that it … Read more
01 The ASCII value of the digit character ‘0’ is 48. Given the following program: main() { char a=’1′,b=’2′; printf(“%c,”,b++); printf(“%d\n”,b-a); } The output of the program is: A) 3,2 B) 25,2 C) 2,2 D) 2,25 Answer: C Explanation: printf(“%c, b++): The initial value of b is ‘2’ (ASCII value 50); b++ is a post-increment, … Read more
Developers working on embedded systems have certainly encountered issues such as tedious programming, difficult debugging, and lengthy log collection. Today, I would like to recommend a powerful tool—DAPLink—that provides a one-stop solution for programming, debugging, and serial logging, making the process incredibly smooth! What is DAPLink? In simple terms, DAPLink is firmware that runs on … Read more
Why Choose boot-wrapper-aarch64? If you are only focused on the Linux kernel, there is no need to run the complete software stack. Using boot-wrapper-aarch64 to boot Linux is quicker, and it is simple and easy to understand, which is sufficient for understanding the ARM boot process. There will be a tutorial later that explains running … Read more
The Ultimate Weapon for Embedded Developers In the field of embedded systems, the bootloader is a critical bridge connecting hardware and the operating system. As the modern successor to U-Boot, Barebox (formerly known as “Das U-Boot v2”) is redefining the possibilities of embedded bootloaders with its innovative design philosophy and developer-friendly features. It not only … Read more
Definition First, let’s look at the definitions of both in the authoritative guide for Cortex-M. 1 Exception Definition According to the authoritative guide for Cortex-M, an exception refers to an event that can alter the normal program flow. When an exception occurs, the processor pauses the currently executing task and executes a dedicated program to … Read more