Development environment: up to the first blinking LED

Set up STM32CubeIDE, the compiler and a debugger, then flash your first firmware. When the first LED lights up, the whole toolchain has been verified.

From source code to running inside the MCU. When the first LED lights, this whole chain is connected correctly.

What you need

Part	Example
IDE	STM32CubeIDE, VS Code + extensions
Compiler	arm-none-eabi-gcc (bundled with the IDE)
Debugger	ST-LINK (built into Nucleo boards), J-Link
Configuration tool	STM32CubeMX (set pins and clocks, then generate code)
Board	A development board such as the Nucleo-F411RE

Steps for the first project

Create a new project by board name
In the CubeMX view, set the LED pin (for example PA5) to GPIO_Output
Generate code and add the toggle code inside while(1)
Build → start a debug session → check that the LED blinks

while (1) {
    HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
    HAL_Delay(500);
}

When the LED does not light up

Check the board schematic: is the LED really on that pin?
Does the debugger connect? (The ST-LINK firmware often needs an update.)
Did you write your code outside a /* USER CODE BEGIN */ block, so it was erased when the code was regenerated?

Once this step works, the compiler, linker, startup code and debugger are all known to be good.