AT43USB325 datasheet(22/109 Pages) ATMEL

22 / 109 page

3355C–USB–4/05

AT43USB325

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 inter-

rupt, 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 Inter-

rupt Mask Register. The USB Bus reset and suspend/resume are grouped in another set of

registers: Suspend/Resume Register, Suspend/Resume Interrupt Enable Register and Sus-

pend/Resume Interrupt Mask Register.

Some applications may include firmware routines lasting for long periods that can not be inter-

rupted. At the same time, other less critical events may need attention after the critical routine is

completed. The AT43USB325 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 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

$002

jmp

EXT_INT0

; IRQ0 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

...

AT43USB325 Datasheet(PDF) 22 Page - ATMEL Corporation

AT43USB325 Datasheet(HTML) 22 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL