+ // Something like this might work, but it compiled larger than the block above
+ // bootloader_start = FLASH_SIZE - (256 << (~high_fuse & 0b110 >> 1));
+
+
+ #if defined(BOOTLOADER_HALFKAY)
+ // http://www.pjrc.com/teensy/jump_to_bootloader.html
+ cli();
+ // disable watchdog, if enabled (it's not)
+ // disable all peripherals
+ // a shutdown call might make sense here
+ UDCON = 1;
+ USBCON = (1<<FRZCLK); // disable USB
+ UCSR1B = 0;
+ _delay_ms(5);
+ #if defined(__AVR_AT90USB162__) // Teensy 1.0
+ EIMSK = 0; PCICR = 0; SPCR = 0; ACSR = 0; EECR = 0;
+ TIMSK0 = 0; TIMSK1 = 0; UCSR1B = 0;
+ DDRB = 0; DDRC = 0; DDRD = 0;
+ PORTB = 0; PORTC = 0; PORTD = 0;
+ asm volatile("jmp 0x3E00");
+ #elif defined(__AVR_ATmega32U4__) // Teensy 2.0
+ EIMSK = 0; PCICR = 0; SPCR = 0; ACSR = 0; EECR = 0; ADCSRA = 0;
+ TIMSK0 = 0; TIMSK1 = 0; TIMSK3 = 0; TIMSK4 = 0; UCSR1B = 0; TWCR = 0;
+ DDRB = 0; DDRC = 0; DDRD = 0; DDRE = 0; DDRF = 0; TWCR = 0;
+ PORTB = 0; PORTC = 0; PORTD = 0; PORTE = 0; PORTF = 0;
+ asm volatile("jmp 0x7E00");
+ #elif defined(__AVR_AT90USB646__) // Teensy++ 1.0
+ EIMSK = 0; PCICR = 0; SPCR = 0; ACSR = 0; EECR = 0; ADCSRA = 0;
+ TIMSK0 = 0; TIMSK1 = 0; TIMSK2 = 0; TIMSK3 = 0; UCSR1B = 0; TWCR = 0;
+ DDRA = 0; DDRB = 0; DDRC = 0; DDRD = 0; DDRE = 0; DDRF = 0;
+ PORTA = 0; PORTB = 0; PORTC = 0; PORTD = 0; PORTE = 0; PORTF = 0;
+ asm volatile("jmp 0xFC00");
+ #elif defined(__AVR_AT90USB1286__) // Teensy++ 2.0
+ EIMSK = 0; PCICR = 0; SPCR = 0; ACSR = 0; EECR = 0; ADCSRA = 0;
+ TIMSK0 = 0; TIMSK1 = 0; TIMSK2 = 0; TIMSK3 = 0; UCSR1B = 0; TWCR = 0;
+ DDRA = 0; DDRB = 0; DDRC = 0; DDRD = 0; DDRE = 0; DDRF = 0;
+ PORTA = 0; PORTB = 0; PORTC = 0; PORTD = 0; PORTE = 0; PORTF = 0;
+ asm volatile("jmp 0x1FC00");