Topic

C Programming

C is the most widely used language for firmware. Sixteen short insights build up the C you need, starting with the compiler chain, with what changes on a microcontroller (MCU) and on a microprocessor (MPU). Each one is a 3–4 minute read with a diagram, C11 code that compiles without warnings, and the output it prints.

Read the first insight

main.cC

void poll_sensors(void);int main(void) {    for (;;) {        poll_sensors();    }}

Insights

From source to binary

Preprocess, compile, assemble and link: what each tool does.

3 min read
Types and integer widths

int, stdint, sizeof, promotion and overflow: how wide is a number?

4 min read
Operators and bit operations

Logical vs bitwise, shifts and masks: set, clear, toggle, test.

4 min read
Control flow

if, switch and loops, and the super-loop that runs forever.

3 min read
Functions, scope and storage

The call stack, pass by value, static and extern.

3 min read
Pointers

Addresses, & and *, pointer arithmetic and fixed-address registers.

3 min read
Arrays and strings

Fixed-size arrays, decay to pointers, and the terminating zero.

3 min read
Structs, unions and bit-fields

Layout and padding, unions, bit-fields and register overlays.

3 min read
The preprocessor and macros

#define, function-like macros, #if and their pitfalls.

3 min read
volatile and const

Registers, interrupt flags and read-only data in Flash.

3 min read
Memory layout

text, rodata, data, bss, heap and stack: where each variable lives.

3 min read
Dynamic memory

malloc, free, fragmentation, and static pools instead.

3 min read
Function pointers and callbacks

Dispatch tables, callbacks and the vector table.

3 min read
Headers and multi-file projects

Declaration vs definition, include guards and private names.

3 min read
enum, typedef and state machines

Named states, switch-based and table-driven state machines.

3 min read
Undefined behaviour and endianness

UB traps the optimiser exploits, and byte order on the wire.

3 min read