main.c

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/wdt.h>

#include "usbdrv.h"
#include "usbdrv/usbdrv.h"

#define F_CPU 16500000L
#include <util/delay.h>

// USB report descriptor, size must match usbconfig.h
PROGMEM const char usbHidReportDescriptor[34] = {
        0x05, 0x01,                    // USAGE_PAGE (Generic Desktop)
        0x09, 0x00,                    // USAGE (Undefined)
        0xa1, 0x01,                    // COLLECTION (Application)
        0x09, 0x00,                    //   USAGE (Undefined)
        0xA1, 0x00,                    //   COLLECTION (Physical)
        0x05, 0x09,                    //     USAGE_PAGE (Button)
        0x19, 0x01,                    //     USAGE_MINIMUM (Button 1)
        0x29, 0x01,                    //     USAGE_MAXIMUM (Button 1)
        0x15, 0x00,                    //     LOGICAL_MINIMUM (0)
        0x25, 0x01,                    //     LOGICAL_MAXIMUM (1)
        0x95, 0x01,                    //     REPORT_COUNT (1)
        0x75, 0x01,                    //     REPORT_SIZE (1)
        0x81, 0x02,                    //     INPUT (Data,Var,Abs)
        0x95, 0x01,                    //     REPORT_COUNT (1)
        0x75, 0x07,                    //     REPORT_SIZE (7)
        0x81, 0x03,                    //     INPUT (Const,Var,Abs)
        0xC0,                          //   END_COLLECTION
        0xC0,                          // END COLLECTION
};

// function which is never used but is required by V-USB
usbMsgLen_t usbFunctionSetup(uchar data[8])
{
    return USB_NO_MSG;
}

int main()
{
    DDRB |= _BV(PB0);              // set PB0 as input
    PORTB |= _BV(PB0);             // set pull-up for PB0
	
    wdt_enable(WDTO_1S);           // enable watchdog
    usbInit();                     // initialize USB connection

    usbDeviceDisconnect();         // disconnect to enforce re-enumeration
    for(uchar i = 0; i < 250; i++) //   in order to be sure that the host and
    {                              //   the device have the same ID
        wdt_reset();
        _delay_ms(2);
    }
    usbDeviceConnect();            // reconnect
    sei();                         // enable interrupts

    while(1)
    {
        wdt_reset();
        usbPoll();                 // required to start sending
                                   //   interrupt signals

        if(usbInterruptIsReady())
        {
            wdt_reset();

            // Reads data from PINB0. Puts 0 into data
            // if the button is not pressed and 1 otherwise.

            uchar interrupt_data;
            if(PINB & (1<<PB0))
                interrupt_data = 0;
            else
                interrupt_data = 1;

            // send data to the host
            usbSetInterrupt(&interrupt_data, 1);
        }
    }

    return 0;
}