Input / Output Modules

SyntropicOS provides non-blocking, debounced drivers for physical user inputs (Buttons, Rotary Encoders) and output indicators (LEDs, Software PWM).

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1. Button Driver (syn_button.h)

The syn_button driver provides debounced GPIO button management with built-in support for: - Debouncing filter with configurable debounce_ms window. - Active-High and Active-Low pin polarities. - Multi-click tap detection (Single, Double, Triple, N-click). - Long-press hold thresholds and auto-repeat streaming. - Multi-button chorded combinations (SYN_ButtonCombo).

Basic Initialization & Single Click

#include <syntropic/input/syn_button.h>

static SYN_Button btn1;

void on_single_click(SYN_Button *btn, void *ctx) {
    // Fired after multi-click window (250ms) expires
}

void app_setup(void) {
    // Port A Pin 2, Active-Low (pull-up), 50ms debounce
    syn_button_init(&btn1, SYN_GPIO_PIN(0, 2), SYN_BUTTON_ACTIVE_LOW, 50);
    syn_button_on_single_click(&btn1, on_single_click, NULL);
}

void app_loop(void) {
    syn_button_update(&btn1);
}

Multi-Click & Long-Press Configuration

// Configure 200ms multi-click evaluation window
syn_button_set_click_window(&btn1, 200);

// Register tap gesture handlers
syn_button_on_single_click(&btn1, on_single, NULL);
syn_button_on_double_click(&btn1, on_double, NULL);
syn_button_on_triple_click(&btn1, on_triple, NULL);
syn_button_on_multi_click(&btn1, on_multi, NULL); // 4+ taps

// Register long press (fires ONCE at 1000ms hold threshold)
syn_button_on_long_press(&btn1, on_long_press, 1000, NULL);

// Register auto-repeat (fires every 100ms while held)
syn_button_on_repeat(&btn1, on_repeat, 100, NULL);

[!NOTE] Entering a Long Press (on_long_press) or firing Auto-Repeat (on_repeat) automatically resets the click counter (click_count = 0), preventing single-click callbacks from triggering when the button is released.

Multi-Button Combinations (SYN_ButtonCombo)

SYN_ButtonCombo enables chorded multi-button presses (e.g. pressing BTN1 + BTN2 simultaneously).

static SYN_Button btn1;
static SYN_Button btn2;
static SYN_ButtonCombo combo;
static const SYN_Button *combo_list[2];

void on_combo_fired(SYN_Button *btn, void *ctx) {
    // Fired when BTN1 and BTN2 are both pressed
}

void app_setup(void) {
    syn_button_init(&btn1, SYN_GPIO_PIN(0, 2), SYN_BUTTON_ACTIVE_LOW, 50);
    syn_button_init(&btn2, SYN_GPIO_PIN(0, 3), SYN_BUTTON_ACTIVE_LOW, 50);

    combo_list[0] = &btn1;
    combo_list[1] = &btn2;
    syn_button_combo_init(&combo, combo_list, 2, on_combo_fired, NULL);
}

void app_loop(void) {
    syn_button_update(&btn1);
    syn_button_update(&btn2);
    syn_button_combo_update(&combo);
}

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2. Rotary Encoder Driver (syn_encoder.h)

Quadrature rotary encoder decoding with velocity tracking and direction calculation.

Function	Description
syn_encoder_init()	Initialize phase A & B GPIO pins
syn_encoder_update()	Sample phase pins and update step counter
syn_encoder_get_value()	Read relative step count
syn_encoder_get_velocity()	Read rotational velocity

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3. Non-Blocking LED Driver (syn_led.h)

Provides pattern blinking, flash sequences, and Morse-code style pattern strings.

#include <syntropic/output/syn_led.h>

static SYN_LED status_led;

void setup(void) {
    syn_led_init(&status_led, LED_BUILTIN, SYN_LED_ACTIVE_HIGH);

    // Blink 500ms ON / 500ms OFF
    syn_led_blink(&status_led, 500, 500);
}

void loop(void) {
    syn_led_update(&status_led);
}

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4. Software PWM Driver (syn_soft_pwm.h)

Enables software PWM output on any arbitrary GPIO pin without requiring hardware timers.

Function	Description
syn_soft_pwm_init()	Initialize pin and frequency
syn_soft_pwm_set_duty()	Set duty cycle (0–255 or 0–100%)
syn_soft_pwm_update()	Service software PWM toggle loop