Datasheet

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16.1.2. MCUCSR – MCU Control and Status Register
When using the I/O specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used. When
addressing I/O Registers as data space using LD and ST instructions, 0x20 must be added to these offset
addresses.
Name:  MCUCSR
Offset:  0x34
Reset:  0
Property:
 
When addressing I/O Registers as data space the offset address is 0x54
Bit 7 6 5 4 3 2 1 0
ISC2
Access
R/W
Reset 0
Bit 6 – ISC2: ISC2: Interrupt Sense Control 2
The Asynchronous External Interrupt 2 is activated by the external pin INT2 if the SREG I-bit and the
corresponding interrupt mask in GICR are set. If ISC2 is written to zero, a falling edge on INT2 activates
the interrupt. If ISC2 is written to one, a rising edge on INT2 activates the interrupt. Edges on INT2 are
registered asynchronously. Pulses on INT2 wider than the minimum pulse width given in the table below
will generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. When changing the
ISC2 bit, an interrupt can occur. Therefore, it is recommended to first disable INT2 by clearing its Interrupt
Enable bit in the GICR Register. Then, the ISC2 bit can be changed. Finally, the INT2 Interrupt Flag
should be cleared by writing a logical one to its Interrupt Flag bit (INTF2) in the GIFR Register before the
interrupt is re-enabled.
Table 16-3. Asynchronous External Interrupt Characteristics
Symbol Parameter Condition Min Typ Max Units
t
INT
Minimum
pulse width
for
asynchronou
s external
interrupt
50 ns
Atmel ATmega32A [DATASHEET]
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