Blinky Example

The Blinky example is the simplest ALP SDK project. It toggles the on-board LED at a fixed interval, verifying that your toolchain, SDK installation, and hardware connection are working correctly.

Source Code

/**
 * Blinky Example - ALP SDK
 *
 * Toggles the on-board LED every 500 ms using the GPIO driver.
 */

#include "alp_gpio.h"
#include "alp_board.h"

/* Board-specific LED pin definition (from BSP) */
/* TODO: Confirm LED pin macro name per board */
#define LED_PIN    BOARD_LED_PIN
#define LED_PORT   BOARD_LED_PORT

static ALP_GPIO_Driver_t *gpio;

/* Simple busy-wait delay */
static void delay_ms(uint32_t ms)
{
    /* TODO: Replace with a timer-based delay or RTOS sleep in production */
    volatile uint32_t count;
    for (uint32_t i = 0; i < ms; i++) {
        for (count = 0; count < 8000; count++) {
            __asm volatile("nop");
        }
    }
}

int main(void)
{
    /* Initialize the board (clocks, pin mux) */
    ALP_Board_Init();

    /* Get GPIO driver and initialize */
    gpio = ALP_GPIO_GetDriver(LED_PORT);
    gpio->Initialize(NULL);
    gpio->PowerControl(ALP_POWER_FULL);

    /* Configure LED pin as push-pull output */
    gpio->SetDirection(LED_PIN, ALP_GPIO_DIR_OUTPUT);
    gpio->SetOutputMode(LED_PIN, ALP_GPIO_OUTPUT_PUSH_PULL);
    gpio->SetValue(LED_PIN, 0);

    while (1) {
        gpio->ToggleValue(LED_PIN);
        delay_ms(500);
    }

    return 0;
}

FreeRTOS Variant

When using FreeRTOS, replace the busy-wait loop with vTaskDelay:

#include "FreeRTOS.h"
#include "task.h"
#include "alp_gpio.h"
#include "alp_board.h"

#define LED_PIN    BOARD_LED_PIN
#define LED_PORT   BOARD_LED_PORT

static ALP_GPIO_Driver_t *gpio;

void blinky_task(void *params)
{
    (void)params;

    gpio = ALP_GPIO_GetDriver(LED_PORT);
    gpio->Initialize(NULL);
    gpio->PowerControl(ALP_POWER_FULL);
    gpio->SetDirection(LED_PIN, ALP_GPIO_DIR_OUTPUT);
    gpio->SetOutputMode(LED_PIN, ALP_GPIO_OUTPUT_PUSH_PULL);

    for (;;) {
        gpio->ToggleValue(LED_PIN);
        vTaskDelay(pdMS_TO_TICKS(500));
    }
}

int main(void)
{
    ALP_Board_Init();

    xTaskCreate(blinky_task, "blinky", 256, NULL, 1, NULL);
    vTaskStartScheduler();

    /* Should never reach here */
    for (;;);
}

Building

mkdir build && cd build
cmake -DBOARD=e1m_x_v2n -DEXAMPLE=blinky ..
cmake --build . --parallel

Expected Behavior

• The on-board LED toggles every 500 ms
• Serial console output (if UART is initialized by the BSP):

[ALP SDK] Blinky example started

Next Steps

• Modify the delay interval to experiment with different blink rates
• Add a second LED or toggle a GPIO pin connected to an oscilloscope
• Move on to the Sensor Reading example