Inital commit

2026-06-14 19:18:06 +02:00
commit 4d15897b87
21 changed files with 1450 additions and 0 deletions
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+/**
+ * @file stk.h
+ * @brief EdgeTX RC library interface for HID joystick mode.
+ *
+ * Reads raw HID input reports from the EdgeTX radio and exposes
+ * 4 analog axes (sticks + throttle) and 24 digital buttons
+ * (switches, rockers, paddles).
+ *
+ * @par Report layout (20 bytes):
+ * @code
+ *   byte  0      : report ID (0x00)
+ *   byte  1      : buttons bits 0..7
+ *   bytes 2..17  : 8 axes x 16-bit LE (HID usage 0x30..0x37)
+ *   bytes 18..19 : buttons bits 8..23
+ * @endcode
+ *
+ * @par Active axes:
+ * | Index | Usage | Physical control | Rest value |
+ * |-------|-------|-----------------|------------|
+ * | 0     | —     | unused          | always 0   |
+ * | 1     | RX    | right stick X   | ~1024      |
+ * | 2     | RY    | right stick Y   | ~1024      |
+ * | 3     | —     | unused          | always 0   |
+ * | 4     | Z     | left stick Y    | 0..2047    |
+ * | 5     | VR    | left stick X    | ~1024      |
+ * | 6..7  | —     | unused          | always 0   |
+ */
+#pragma once
+
+#include <stdint.h>
+
+// ---------------------------------------------------------------------------
+// Axis range (10-bit ADC on the radio)
+// ---------------------------------------------------------------------------
+
+#define STK_AXIS_MIN   0
+#define STK_AXIS_MAX   2047
+#define STK_AXIS_MID   1024
+
+// ---------------------------------------------------------------------------
+// Default device IDs (EdgeTX radio in HID joystick mode)
+// ---------------------------------------------------------------------------
+
+#define STK_DEFAULT_VID  0x1209
+#define STK_DEFAULT_PID  0x4F54
+
+// ---------------------------------------------------------------------------
+// Configuration
+// ---------------------------------------------------------------------------
+
+typedef struct {
+    uint16_t vendor_id;
+    uint16_t product_id;
+} stk_config_t;
+
+// ---------------------------------------------------------------------------
+// Radio state
+//
+// axes[] holds all 8 HID axes (indices 0-7). Only indices 1, 2, 4, 5
+// are wired to physical controls. The rest stay at 0.
+//
+// buttons is a 24-bit bitmask: bit N set = switch/button N+1 pressed.
+// ---------------------------------------------------------------------------
+
+#define STK_NUM_AXES    8
+#define STK_NUM_BUTTONS 24
+
+typedef struct {
+    int16_t axes[STK_NUM_AXES];
+    uint32_t buttons;
+} stk_state_t;
+
+// ---------------------------------------------------------------------------
+// Convenience accessors for the 4 active axes
+// ---------------------------------------------------------------------------
+
+static inline int16_t stk_right_x(stk_state_t const* s) {
+    return s->axes[1];
+}
+
+static inline int16_t stk_right_y(stk_state_t const* s) {
+    return s->axes[2];
+}
+
+static inline int16_t stk_throttle(stk_state_t const* s) {
+    return s->axes[4];
+}
+
+static inline int16_t stk_left_x(stk_state_t const* s) {
+    return s->axes[5];
+}
+
+// ---------------------------------------------------------------------------
+// Button bitmask helpers (bit 0 = first switch, bit 23 = last)
+// ---------------------------------------------------------------------------
+
+static inline bool stk_button_pressed(stk_state_t const* s,
+                                      uint8_t index) {
+    if (index >= STK_NUM_BUTTONS)
+        return false;
+    return (s->buttons >> index) & 1;
+}
+
+// ---------------------------------------------------------------------------
+// API
+// ---------------------------------------------------------------------------
+
+/**
+ * Open the HID radio device.
+ * config must remain valid for the lifetime of the open session.
+ * Returns 0 on success, -1 on failure.
+ */
+int stk_open(stk_config_t const* config);
+
+/**
+ * Read the current radio state (non-blocking).
+ * Returns 0 on success, -1 on failure or no new data.
+ */
+int stk_read(stk_state_t* state);
+
+/**
+ * Close the radio device. Safe to call multiple times.
+ */
+void stk_close(void);