GD32 and RP2040: Add platform support for eject buttons (#135)

lib/ZuluSCSI_platform_GD32F205/ZuluSCSI_platform.cpp

@@ -218,6 +218,10 @@ void platform_init()
     gpio_bit_set(LED_PORT, LED_PINS);
     gpio_init(LED_PORT, GPIO_MODE_OUT_PP, GPIO_OSPEED_2MHZ, LED_PINS);
 
+    // Ejection buttons
+    gpio_init(EJECT_1_PORT, GPIO_MODE_IPU, 0, EJECT_1_PIN);
+    gpio_init(EJECT_2_PORT, GPIO_MODE_IPU, 0, EJECT_2_PIN);
+
     // SWO trace pin on PB3
     gpio_init(GPIOB, GPIO_MODE_AF_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_3);
 }
@@ -495,7 +499,27 @@ void platform_poll()
 
 uint8_t platform_get_buttons()
 {
-    return 0;
+    // Buttons are active low: internal pull-up is enabled,
+    // and when button is pressed the pin goes low.
+    uint8_t buttons = 0;
+    if (!gpio_input_bit_get(EJECT_1_PORT, EJECT_1_PIN))   buttons |= 1;
+    if (!gpio_input_bit_get(EJECT_2_PORT, EJECT_2_PIN))   buttons |= 2;
+
+    // Simple debouncing logic: handle button releases after 100 ms delay.
+    static uint32_t debounce;
+    static uint8_t buttons_debounced = 0;
+
+    if (buttons != 0)
+    {
+        buttons_debounced = buttons;
+        debounce = millis();
+    }
+    else if ((uint32_t)(millis() - debounce) > 100)
+    {
+        buttons_debounced = 0;
+    }
+
+    return buttons_debounced;
 }
 
 /***********************/

lib/ZuluSCSI_platform_GD32F205/ZuluSCSI_v1_0_gpio.h

@@ -138,3 +138,11 @@
 #define LED_PINS     (LED_I_PIN | LED_E_PIN)
 #define LED_ON()     gpio_bit_reset(LED_PORT, LED_PINS)
 #define LED_OFF()    gpio_bit_set(LED_PORT, LED_PINS)
+
+// Ejection buttons are available on expansion header J303.
+// PE5 = channel 1, PE6 = channel 2
+// Connect button between GPIO and GND pin.
+#define EJECT_1_PORT    GPIOE
+#define EJECT_1_PIN     GPIO_PIN_5
+#define EJECT_2_PORT    GPIOE
+#define EJECT_2_PIN     GPIO_PIN_6

lib/ZuluSCSI_platform_GD32F205/ZuluSCSI_v1_1_gpio.h

@@ -182,4 +182,12 @@
 #define LED_E_PIN    GPIO_PIN_5
 #define LED_PINS     (LED_I_PIN | LED_E_PIN)
 #define LED_ON()     gpio_bit_reset(LED_PORT, LED_PINS)
-#define LED_OFF()    gpio_bit_set(LED_PORT, LED_PINS)
+#define LED_OFF()    gpio_bit_set(LED_PORT, LED_PINS)
+
+// Ejection buttons are available on expansion header J303.
+// PE5 = channel 1, PE6 = channel 2
+// Connect button between GPIO and GND pin.
+#define EJECT_1_PORT    GPIOE
+#define EJECT_1_PIN     GPIO_PIN_5
+#define EJECT_2_PORT    GPIOE
+#define EJECT_2_PIN     GPIO_PIN_6

lib/ZuluSCSI_platform_RP2040/ZuluSCSI_platform.cpp

@@ -621,14 +621,32 @@ void platform_poll()
 
 uint8_t platform_get_buttons()
 {
-#ifdef ENABLE_AUDIO_OUTPUT
-    uint8_t pins = 0x00;
+    uint8_t buttons = 0;
+
+#if defined(ENABLE_AUDIO_OUTPUT)
     // pulled to VCC via resistor, sinking when pressed
-    if (!gpio_get(GPIO_EXP_SPARE)) pins |= 0x01;
-    return pins;
-#else
-    return 0;
+    if (!gpio_get(GPIO_EXP_SPARE)) buttons |= 1;
+#elif defined(GPIO_I2C_SDA)
+    // SDA = button 1, SCL = button 2
+    if (!gpio_get(GPIO_I2C_SDA)) buttons |= 1;
+    if (!gpio_get(GPIO_I2C_SCL)) buttons |= 2;
 #endif
+
+    // Simple debouncing logic: handle button releases after 100 ms delay.
+    static uint32_t debounce;
+    static uint8_t buttons_debounced = 0;
+
+    if (buttons != 0)
+    {
+        buttons_debounced = buttons;
+        debounce = millis();
+    }
+    else if ((uint32_t)(millis() - debounce) > 100)
+    {
+        buttons_debounced = 0;
+    }
+
+    return buttons_debounced;
 }
 
 /*****************************************/