AT43USB326 datasheet(18/102 Pages) ATMEL

18 / 102 page

AT43USB326

3313D–USB–04/06

Figure 4. Oscillator and PLL

Reset and

Interrupt Handling

The AT43USB326 provides 12 different interrupt sources with 4 separate reset vectors, each

with a separate program vector in the program memory space. Nine of the interrupt sources

share 2 interrupt reset vectors. These nine are the USB related interrupts. All interrupts are

assigned individual enable bits which must be set (one) together with the I-bit in the status reg-

ister in order to enable the interrupt.

The lowest addresses in the program memory space are automatically defined as the Reset

and Interrupt vectors. The complete list of vectors is shown in Table 6. The list also determines

the priority levels of the different interrupts. The lower the address, the higher is the priority

level. RESET has the highest priority, and next is INT0 – the USB Suspend and Resume Inter-

rupt, etc.

AT43USB326

XTAL1

XTAL2

LFT

6.000 MHz

0.01 UF

0.22 UF

100

Table 6. Reset and Interrupt Vectors

Vector No.

Program Address

Source

Interrupt Definition

$000

RESET

External Reset, Power-on Reset and

Watchdog Reset

$002

INT0

USB Suspend and Resume

$00E

TIMER0, OVF

Timer/Counter0 Overflow

$018

USB HW

USB Hardware

AT43USB326 Datasheet(PDF) 18 Page - ATMEL Corporation