sun_usb: doesn't work with SERIAL_SOFT_LOGIC_NEGATIVE commented out

[tmk]

When SERIAL_SOFT_LOGIC_NEGATIVE is commented out RXD interrupt should be triggered on falling edge instead of rising.

Interruption setting code in config.h

/* RXD Interupt */
#define SERIAL_SOFT_RXD_INIT()      do { \
    /* pin configuration: input with pull-up */ \
    SERIAL_SOFT_RXD_DDR &= ~(1<<SERIAL_SOFT_RXD_BIT); \
    SERIAL_SOFT_RXD_PORT |= (1<<SERIAL_SOFT_RXD_BIT); \
    /* enable interrupt: INT2(rising edge) */ \
    EICRA |= ((1<<ISC21)|(1<<ISC20)); \
    EIMSK |= (1<<INT2); \
    sei(); \
} while (0)

should be:

    EICRA |= ((1<<ISC21)|(0<<ISC20)); \

http://deskthority.net/workshop-f7/sun-usb-conversion-with-arduino-micro-and-tmk-t10779.html#p233452