fix: yet more wiznet bugs, reconnects, led status indicators

include/gpio.h

@@ -3,7 +3,20 @@
 
 #include <stdint.h>
 
-// Function prototype for initializing GPIO
+// Status states
+typedef enum {
+  LED_STATE_OFF,
+  LED_STATE_ON,       // ok
+  LED_STATE_WARNING,  // slow blink
+  LED_STATE_ERROR,    // fast blink
+  LED_STATE_BUSY      // "breathing"
+} led_state_t;
+
+// Initialize GPIO
 void init_gpio(void);
 
+// LED status handling
+void led_status_set(led_state_t state);
+void led_status_process(void);
+
 #endif  // GPIO_H