• Scan six menu buttons with debounce.
• Read eight isolated 24 V digital inputs.
• Capture two high-speed counter inputs using timer input-capture/counter mode up to 10 kHz.
• Drive four protected transistor outputs.
• Exchange process data with the Linux SOM over SPI or UART.
• Feed TPS3828 watchdog with a periodic heartbeat.
• Manage sensor expansion buses: I2C, SPI, UART, GPIO interrupts.

C
#include "main.h"
#include <stdbool.h>
#include <stdint.h>

// TODO: replace GPIO ports/pins after schematic pin assignment.
#define WDI_GPIO_Port GPIOA
#define WDI_Pin       GPIO_PIN_0

static void feed_watchdog(void) {
    HAL_GPIO_TogglePin(WDI_GPIO_Port, WDI_Pin);
}

static void process_inputs(void) {
    // TODO: read ISO_DI1..ISO_DI8 GPIOs and counter timer registers.
}

static void update_outputs(void) {
    // TODO: drive DO1_CTRL..DO4_CTRL with validated command state.
}

int main(void) {
    HAL_Init();
    SystemClock_Config();
    MX_GPIO_Init();
    MX_SPI1_Init();
    MX_TIM2_Init();
    MX_TIM3_Init();

    uint32_t last_wd = HAL_GetTick();
    while (1) {
        process_inputs();
        update_outputs();
        if ((HAL_GetTick() - last_wd) >= 100) {
            last_wd = HAL_GetTick();
            feed_watchdog();
        }
    }
}