captouch_joystick.h

#include "Adafruit_TinyUSB.h"

#pragma once

#define MAX_AXIS    32767

#define ATTRIBUTE_PACKED  __attribute__((packed, aligned(1)))

// This overlays the HID report defined by desc_hid_report[].
typedef struct ATTRIBUTE_PACKED {
    uint32_t  buttons;
    int16_t   xAxis;
    int16_t	yAxis;
} HID_JoystickReport_Data_t;

// HID report descriptor 2 axes (16 bits per axis), 32 buttons
// Single Report (no report ID) descriptor
uint8_t const desc_hid_report[] =
{
    0x05, 0x01,        // Usage Page (Generic Desktop Ctrls)
    0x09, 0x04,        // Usage (Joystick)
    0xA1, 0x01,        // Collection (Application)
    0x15, 0x00,        //   Logical Minimum (0)
    0x25, 0x01,        //   Logical Maximum (1)
    0x35, 0x00,        //   Physical Minimum (0)
    0x45, 0x01,        //   Physical Maximum (1)
    0x75, 0x01,        //   Report Size (1)
    0x95, 0x20,        //   Report Count (32)
    0x05, 0x09,        //   Usage Page (Button)
    0x19, 0x01,        //   Usage Minimum (0x01)
    0x29, 0x20,        //   Usage Maximum (0x20)
    0x81, 0x02,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
    0x05, 0x01,        //   Usage Page (Generic Desktop Ctrls)
    0x16, 0x01, 0x80,  //   Logical Minimum (-32767)
    0x36, 0x01, 0x80,  //   Physical Minimum (-32767)
    0x26, 0xFF, 0x7F,  //   Logical Maximum (32767)
    0x46, 0xFF, 0x7F,  //   Physical Maximum (32767)
    0x09, 0x30,        //   Usage (X)
    0x09, 0x31,        //   Usage (Y)
    0x75, 0x10,        //   Report Size (16)
    0x95, 0x02,        //   Report Count (2)
    0x81, 0x02,        //   Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
    0xC0,              // End Collection
};


class TUJoystick {
    public:
        inline void begin(void);
        inline void end(void);
        inline void loop(void);
        inline void write(void) { this->_usb_hid.sendReport(0, &this->_report, (uint8_t)sizeof(this->_report)); };
        void write(void *report);
        void press(int b);
        void release(int b);
        inline void releaseAll(void) { this->_report.buttons = 0; };

        inline void buttons(uint32_t b) { this->_report.buttons = b; };
        inline void xAxis(int a) { this->_report.xAxis = a; };
        inline void yAxis(int a) { this->_report.yAxis = a; };

        inline bool ready(void) { return this->_usb_hid.ready(); };

    protected:
        HID_JoystickReport_Data_t _report;
        uint32_t _start_millis;
        Adafruit_USBD_HID _usb_hid;
};

void TUJoystick::begin(void)
{
    this->_usb_hid.setPollInterval(1);
    this->_usb_hid.setReportDescriptor(desc_hid_report, sizeof(desc_hid_report));
    this->_usb_hid.setStringDescriptor("TinyUSB Joystick");

    this->_report.buttons = 0;
    this->_report.xAxis = this->_report.yAxis = 0;
    this->_usb_hid.begin();
    this->_start_millis = millis();
}

void TUJoystick::end(void)
{
    this->_report.buttons = 0;
    this->_report.xAxis = this->_report.yAxis = 0;
    this->write();
}

void TUJoystick::write(void *report)
{
    memcpy(&this->_report, report, sizeof(this->_report));
    this->write();
}

// Avoid USB writes more than once per millisecond
void TUJoystick::loop(void)
{
    if (this->_start_millis != millis()) {
        this->write();
        this->_start_millis = millis();
    }
}

void TUJoystick::press(int b)
{
    b &= 0x1F; // Limit value between 0..31
    this->_report.buttons |= (uint32_t)1 << b;
}

void TUJoystick::release(int b)
{
    b &= 0x1F; // Limit value between 0..31
    this->_report.buttons &= ~((uint32_t)1 << b);
}