📊CAB202 | 2024 S1

Microprocessors and Digital Systems

Table Of Contents

• Week 1: Microcontroller Fundamentals

• Week 2: Digital Representations and Operations

• Week 3: Microcontroller Interfacing

• Week 4: Assembly Programming

• Week 5: Introduction to C

• Week 6: Pointers, Arrays, Functions and Scope

• Week 7: C for Embedded Systems

• Week 8: OVERVIEW SUMMARY

• Week 9: Timers: PWM and ADCs

• Week 10: Serial Communication and Strings

• Week 11: State Machines, Debouncing and Debugging

• Week 12: Serial Protocol Design and Parsing

• Week 13: Review

CAB202 Microprocessors and Digital Systems

Describe what CAB202 is about

Week 1: Microcontroller Fundamentals

Week 2: Digital Representations and Operations

Week 3: Microcontroller Interfacing

Week 4: Assembly Programming

Week 5: Introduction to C

Week 6: Pointers, Arrays, Functions and Scope

Pointers in C, a pointer is a special type of variable that can store the address of another variable in memory. For example, if you have a variable called num that stores the value 10, you can create a pointer called ptr that stores the address of num. This means that ptr points to num, or in other words, ptr references num.

To declare a pointer, you need to specify the type of the variable that it points to, followed by an asterisk (*) and the name of the pointer. For example, if you want to declare a pointer to an integer (int), you can write:

int *ptr; // Pointer to int

This code declares a pointer variable named ptr, but this variable is not a int itself. It is a pointer that can be used to point to a int variable. You can think of a pointer as a signpost that shows the way to another variable.

Internally, pointers store a memory address, which is a number that identifies a location in the computer's memory where some data is stored. For example, if num is stored at the memory address 1000, then ptr will store the value 1000 as well. You can use the ampersand (&) operator to get the address of a variable.

int num = 10; // Declare and initialise a int variable

int *ptr; // Declare a pointer to int

ptr = # // Assign the address of num to ptr

This code assigns the address of num to ptr, which means that ptr now points to num. You can use the printf function to print the address of a variable using %p format specifier. For example:

printf("Address of num: %p\n", &num); // Print the address of num
printf("Value of ptr: %p\n", ptr); // Print the value of ptr

This code will print something like

Address of num: 0x3e8
Value of ptr: 0x3e8

Note that the actual memory address may vary depending on your system and compiler. The 0x prefix indicates that the address is in hexadecimal (base 16) notation, which is commonly used to represent memory addresses.

To access the value of the variable tha ta pointer points to, you can use the asterisk (*) operator again, but this time as a dereference operator. This operator returns the value of the variable located at the address specified by its operand. For example:

printf("Value of num: %d\n", num); // Print the value of num
printf("Value of *ptr: %d\n", *ptr); // Print the value of *ptr

This code will print

Value of num: 10
Value of *ptr: 10

As you can see, changing the value of *ptr also changes the value of num, because they are the same variable You can also make a pointer point to different variable by assigning a new address to it. For example:

int num1 = 10; // Declare and initialise a int variable
int num2 = 20; // Delcare and initialise another int variable
int *ptr; // Declare a pointer to int
ptr = &num1; // Make ptr point to num1
printf("Value of *ptr: %d\n", *ptr); // Print the value of *ptr
ptr = &num2; // Make ptr point to num2
printf("Value of *ptr: %d\n", *ptr); // Print the value of *ptr

This code will print:

Value of *ptr: 10
Value of *ptr: 20

As you can see, the value of *ptr changes depending on which variable it points to. You can also use pointers to pass variables by reference to functions, or to access elements of arrays using pointer arithmetic, but those are more advanced topics.

Week 7: C for Embedded Systems

Week 8: OVERVIEW SUMMARY

Week 9: Timers: PWM and ADCs

Week 10: Serial Communication and Strings

Week 11: State Machines, Debouncing and Debugging

Week 12: Serial Protocol Design and Parsing

Week 13: Review