This project demonstrates how to blink multiple LEDs on a breadboard using the NXP FRDM MCX A346 development board, simulating a simple traffic light. It goes beyond the standard MCUXpresso SDK examples and shows how hobbyists can take their first steps into professional embedded programming. The goal is to highlight both accessibility for newcomers and transferable skills in embedded C, hardware setup, and debugging.

I am a hobby programmer with a strong interest in robotics. My background includes Arduino Uno projects, which are widely used for prototyping. In professional settings, however, engineers often transition to boards from NXP or STMicroelectronics. I wanted to explore how different the experience is when moving from Arduino to professional boards and IDEs, especially since tutorials for hobbyists are limited.

My first impression: it's a noticeable shift, but not overwhelming. NXP's documentation and tools make the process approachable. Setting up the IDE, installing the SDK, and importing example projects has been straightforward. This series aims to show that embedded programming with professional tools is within reach for hobbyists - it just requires a different learning approach.

• MCUXpresso IDE installed
• NXP FRDM MCX A346 board
• SDK example gpio_led_output (found under driver_examples > gpio)
• Breadboard, LEDs, resistors, and jumper wires

To import SDK examples: open the Quickstart Panel in MCUXpresso IDE and select Import SDK example(s).... If the panel is hidden, go to Window > Show View > Quickstart Panel.

1. Create a new C project in MCUXpresso IDE.
2. Copy app.h and hardware_init.c from the gpio_led_output example (found under board) into the board folder of your new project.
3. Ensure the Project Explorer is visible: Window > Show View > Project Explorer.

Connect the LEDs to GPIO pins 8, 9, and 10 of GPIO3, each with a suitable resistor. Ensure correct polarity (anode to GPIO, cathode to ground). See Figure 1 for wiring layout.

• If LEDs behave unexpectedly, check for loose or touching wires.
• Verify LED orientation (anode vs. cathode).
• Confirm resistor values are appropriate.

gpio_pin_config_t

This structure configures a GPIO pin:

• pinDirection: input or output (here, kGPIO_DigitalOutput)
• outputLogic: default logic level (0 = low, 1 = high)

GPIO_PinInit()

Initializes a GPIO pin with three parameters:

1. base: GPIO peripheral block
2. pin: GPIO pin number
3. config: pointer to configuration structure

GPIO_PortToggle()

Toggles the state of one or more pins on a GPIO port. The mask parameter uses bit shifting to select the pin. For example, 1u << 10 creates a mask for pin 10.

{} - Struct initialization

Curly braces are used to initialize a structure. For example:

gpio_pin_config_t led_config = {
    kGPIO_DigitalOutput,
    0,
};

This sets the pinDirection to output and the outputLogic to low (0 volts). The values inside the braces match the order of fields in the gpio_pin_config_t struct.

* - Pointer indicator

The asterisk denotes a pointer, which holds the memory address of another variable. Example:

const gpio_pin_config_t *config

This means the function expects a pointer to a gpio_pin_config_t structure. When calling:

GPIO_PinInit(GPIO3, 10, &led_config);

we pass the address of led_config using &.

& - Address-of operator

The ampersand symbol means "address of". It's how you pass a variable's memory location to a function that expects a pointer.

Example:

&led_config

This gives the function direct access to the struct in memory, rather than a copy.

<< - Bitwise shift operator

The shift operator moves bits left or right. It's used to create bitmasks for selecting pins.

Example:

1u << 10

This shifts the binary value 1 left by 10 positions, producing a mask that targets pin 10.

u - Unsigned integer suffix

Adding u after a number makes it an unsigned integer.

Example:

1u

This ensures the value is treated as non-negative, which is important for bitwise operations. Using 1u avoids unexpected behavior when shifting bits.