My Journey in Embedded C Programming

Introduction

My journey to C programming began as a result of my deep interest in the field of embedded systems. Growing up, I loved playing with electronic gadgets, whether good or bad ones. I loved building things with them, and it was even more joyful when I found someone using what I built. At age 11, I would visit dump sites to sort and pick up spoiled electronics gadgets that I would piece together(reverse engineer) to build something useful. For instance, I built a mini-air conditioner from a trash plastic container, a CPU fan, and pipes. I reverse-engineered spoiled rechargeable lanterns to light up my grandma's house in several instances. This passion for building consumer electronics devices fueled my interest in becoming an embedded systems engineer.

The Beginning: The World of Embedded C

To achieve my goal of becoming an embedded systems engineer, I taught myself the basics of electronics and then followed an Arduino programming tutorial by Paul McWhorter (Top Tech Boy) on YouTube, where I was introduced to C and C++ programming using the Arduino IDE. After taking the lessons from Paul McWhorter, I was equipped with basic electronics and C programming skills that enabled me to develop cool projects like an automatic medicine dispenser, automatic water pump controllers, IoT soil moisture monitoring, a smart waste management system, and many others. Despite being able to handle these cool projects with my Arduino programming skills, I saw a strong need to learn raw C programming language, where I can learn low-level programming, and write efficient C code without the use of libraries, as is with the Arduino environment.

While searching for the right C programming course to enroll in, I got into an embedded systems mentorship program organized by a mentor, Agha Kingsley. Through this mentorship program, I was guided to enroll in a Udemy course on "Microcontroller Embedded C Programming: Absolute Beginners" by Kiran Nayak. This course became the launchpad that helped me learn and understand the basic and key concepts like pointers, heap, stack, struct, and unions in C programming. So far, I have gotten a hands-on experience with low-level programming, driver development, and understanding the inner workings of the STM32 microcontroller.

A Game-Changing Discovery: Showcasing the Significance of Pointers

In taking the C programming course, the area that interested me the most was learning about pointers. I gave much attention to studying pointers when I realized that they can enable direct hardware access, making them essential in embedded programming. Getting an in-depth knowledge and understanding of pointers was quite challenging until I came across a lecture playlist on understanding pointers in C by Piyush Itankar on his Pyjama Brah! YouTube Channel. From Piyush's lectures on pointers, I saw a clear picture of why pointers are used in embedded systems.

Now, when I think about pointers, what comes to mind is how memory interacts with the CPU, where memory is arranged in a structured manner, and the CPU accesses it using different buses. A pointer is a number representing a memory address. This address can be 0 or any positive integer corresponding to the location of a byte in memory. Similarly, another way to understand pointers would be to imagine reading a book where you start on page 1 (memory location 0x0001), but instead of proceeding sequentially, you jump to page 20 (0x0014 in hex), with "20" representing an address that points to specific content. In this analogy, the book represents the memory, the page number corresponds to the address, and the CPU is like the person reading, navigating through memory by jumping to the required addresses to access data.

A Real-World Project That Strengthened My Understanding of Pointers

Previously, if a typical me wants to turn ON an LED, especially with the use of Arduino library (which uses C++ on top of Embedded C), here is the code I would write below:

#define LED_PIN 13 // Define which pin LED is connected to

void setup() {

 pinMode(LED_PIN, OUTPUT); // Set the pin as output

}

void loop() {

 digitalWrite(LED_PIN, HIGH); // Turn on the LED

}

If you are a good programmer, you would understand that the code above uses built-in functions that are abstractions over the low-level memory access, making it easier for beginners. However, now that I have gotten a good hold of C programming with a good understanding of pointers, this is what my LED code will look like:

#define LED_PIN (*(volatile unsigned char*) 0x25) // Assume 0x25 is the LED memory-mapped address

void turnOnLED() {

   LED_PIN = 1; // Write to memory location

}

Looking at the two codes above, the latter directly writes to the LED control register in embedded systems, where peripherals are mapped to memory addresses. This makes the program execution very fast and gives me maximum control compared to the former. The more I explore embedded systems, the more I realize how pointers are to everything from simple LED blink programs to complex sensor systems.

Wrapping Up

As I continue my journey to becoming an exceptional embedded systems engineer, I will ensure to master the A-Z of pointers. Pointers are a key to opening the door to optimizing code, controlling hardware directly, and ensuring that embedded systems run efficiently on limited resources. My journey with embedded C and pointers is far from over, and I am excited about the projects and challenges that await.