Datasheet

ATmega16U4/32U4 [DATASHEET]

Atmel-7766J-USB-ATmega16U4/32U4-Datasheet_04/2016

Notes: 1. When the BOOTRST Fuse is programmed, the device will jump to the Boot Loader address at reset, see

“Memory Programming” on page 353.

2. When the IVSEL bit in MCUCR is set, Interrupt Vectors will be moved to the start of the Boot Flash Section.

The address of each Interrupt Vector will then be the address in this table added to the start address of the

Boot Flash Section.

The table shows reset and Interrupt Vectors placement for the various combinations of BOOTRST and IVSEL

settings. If the program never enables an interrupt source, the Interrupt Vectors are not used, and regular

program code can be placed at these locations. This is also the case if the Reset Vector is in the Application

section while the Interrupt Vectors are in the Boot section or vice versa.

Note: 1. The Boot Reset Address is shown in Table 27-4 on page 340. For the BOOTRST Fuse “1” means

unprogrammed while “0” means programmed.

9.1.1 Moving Interrupts Between Application and Boot Space

The General Interrupt Control Register controls the placement of the Interrupt Vector table.

28 $0036 USART1TX USART1 Tx Complete

29 $0038 ANALOG COMP Analog Comparator

30 $003A ADC ADC Conversion Complete

31 $003C EE READY EEPROM Ready

32 $003E TIMER3 CAPT Timer/Counter3 Capture Event

33 $0040 TIMER3 COMPA Timer/Counter3 Compare Match A

34 $0042 TIMER3 COMPB Timer/Counter3 Compare Match B

35 $0044 TIMER3 COMPC Timer/Counter3 Compare Match C

36 $0046 TIMER3 OVF Timer/Counter3 Overflow

37 $0048 TWI 2-wire Serial Interface

38 $004A SPM READY Store Program Memory Ready

39 $004C TIMER4 COMPA Timer/Counter4 Compare Match A

40 $004E TIMER4 COMPB Timer/Counter4 Compare Match B

41 $0050 TIMER4 COMPD Timer/Counter4 Compare Match D

42 $0052 TIMER4 OVF Timer/Counter4 Overflow

43 $0054 TIMER4 FPF Timer/Counter4 Fault Protection Interrupt

Table 9-2. Reset and Interrupt Vectors Placement

BOOTRST IVSEL Reset Address Interrupt Vectors Start Address

1 0 0x0000 0x0002

1 1 0x0000 Boot Reset Address + 0x0002

0 0 Boot Reset Address 0x0002

0 1 Boot Reset Address Boot Reset Address + 0x0002

Table 9-1. Reset and Interrupt Vectors(cont’d)

Vector

No.

Program

Address

(2)

Source Interrupt Definition