AT43USB355 datasheet(21/115 Pages) ATMEL

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AT43USB355

2603G–USB–04/06

The most typical and general program setup for the Reset and Interrupt Vector Addresses are:

USB related interrupt events are routed to reset vectors 13 and 2 through a separate set of

interrupt, interrupt enable and interrupt mask registers that are mapped to the data SRAM

space. These interrupts must be enabled though their control register bits. In the event an

interrupt is generated, the source of the interrupt is identified by reading the interrupt registers.

The USB frame and transaction related interrupt events, such as Start of Frame interrupt, are

grouped in one set of registers: USB Interrupt Flag Register, USB Interrupt Enable Register

and USB Interrupt Mask Register. The USB Bus reset and suspend/resume are grouped in

another set of registers: Suspend/Resume Register, Suspend/Resume Interrupt Enable Reg-

ister and Suspend/Resume Interrupt Mask Register.

Some applications may include firmware routines lasting for long periods of time that cannot

be interrupted. At the same time, other less critical events may need attention after the critical

routine is completed. The AT43USB355 solves this problem by having interrupt mask registers

in addition to the interrupt enable registers of the USB related interrupts. The difference

between the mask and the enable registers is:

•

The enable register enables the interrupt so it is captured into the interrupt register. If it is

not enabled and an interrupt occurs, the interrupt will be lost,

•

The mask register merely masks the interrupt from interrupting the CPU. Upon

unmasking, the pending interrupt is triggered.

Address

Labels

Code

Comments

$000

jmp

RESET

; Reset Handler

$004

jmp

EXT_INT1

; IRQ1 Handler

$00E

jmp

TIM0_OVF

; Timer0 Overflow

Handler

$018

jmp

USB_HW

; USB Handler

;

$00d

MAIN:

ldi r16, high (RAMEND)

; Main Program

start

$00e

out SPH, r16

$00f

ldi r16, low (RAMEND)

$010

out SPL, r16

$011

<instr> xxx

...

AT43USB355 Scheda tecnica(PDF) 21 Page - ATMEL Corporation

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