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