AT43USB320A-AC Atmel, AT43USB320A-AC Datasheet - Page 29

• Manufacturer Part Number: AT43USB320A-AC
• Description: IC USB MCU EMBED HUB AVR 100LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB320A-AC

• Applications: USB Hub/Microcontroller
• Core Processor: AVR
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: SPI Serial, USB, UART
• Number Of I /o: 32
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 100-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Program Memory Type: -

External Interrupts
Interrupt
Response Time
1443E–USB–4/04
The external interrupts are triggered by the INT0 and INT1 pins. Observe that, if enabled, the
INT0/INT1 interrupt will trigger even if the INT0/INT1 pins are configured as outputs. This fea-
ture provides a way of generating a software interrupt. The external interrupts can be triggered
by a falling or rising edge or a low level. This is set up as indicated in the specification for the
MCU Control Register (MCUCR) and the Interrupt Sense Control Register (ISCR). When the
external interrupt is enabled and is configured as level triggered, the interrupt will trigger as
long as the pin is held low. The external interrupts are set up as described in the specification
for the MCU Control Register (MCUCR).
The interrupt execution response for all the enabled AVR interrupts is 4 clock cycles minimum.
4 clock cycles after the interrupt flag has been set, the program vector address for the actual
interrupt handling routine is executed. During this 4 clock cycle period, the Program Counter (2
bytes) is pushed onto the Stack, and the Stack Pointer is decremented by 2. The vector is nor-
mally a jump to the interrupt routine, and this jump takes 3 clock cycles. If an interrupt occurs
during execution of a multi-cycle instruction, this instruction is completed before the interrupt is
served.
A return from an interrupt handling routine (same as for a subroutine call routine) takes 4 clock
cycles. During these 4 clock cycles, the Program Counter (2 bytes) is popped back from the
Stack, the Stack Pointer is incremented by 2, and the I flag in SREG is set. When the AVR
exits from an interrupt, it will always return to the main program and execute one more instruc-
tion before any pending interrupt is served.
AT43USB320A
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