Rainbow Electronics AT90LS4433 - Manual (Page 31)

31
AT90S/LS4433
1042G–AVR–09/02
• Bits 3, 2 – ISC11, ISC10: Interrupt Sense Control 1 Bit 1 and Bit 0
The External Interrupt 1 is activated by the external pin INT1 if the SREG I-flag and the
corresponding interrupt mask in the GIMSK are set. The level and edges on the external
INT1 pin that activate the interrupt are defined in Table 7.
The value on the INT1 pin is sampled before detecting edges. If edge or toggle interrupt
is selected, pulses that last longer than one clock period will generate an interrupt.
Shorter pulses are not guaranteed to generate an interrupt. If low-level interrupt is
selected, the low level must be held until the completion of the currently executing
instruction to generate an interrupt.
• Bits 1, 0 – ISC01, ISC00: Interrupt Sense Control 0 Bit 1 and Bit 0
The External Interrupt 0 is activated by the external pin INT0 if the SREG I-flag and the
corresponding interrupt mask are set. The level and edges on the external INT0 pin that
activate the interrupt are defined in Table 8.
The value on the INT0 pin is sampled before detecting edges. If edge or toggle interrupt
is selected, pulses that last longer than one clock period will generate an interrupt.
Shorter pulses are not guaranteed to generate an interrupt. If low-level interrupt is
selected, the low level must be held until the completion of the currently executing
instruction to generate an interrupt.
Sleep Modes To enter the sleep modes, the SE bit in MCUCR must be set (one) and a SLEEP instruc-
tion must be executed. The SM bit in the MCUCR Register selects which sleep mode
(Idle or Power-down) will be activated by the SLEEP instruction. If an enabled interrupt
occurs while the MCU is in a sleep mode, the MCU wakes up, executes the interrupt
routine, and resumes execution from the instruction following SLEEP. The contents of
the Register File and I/O memory are unaltered. If a reset occurs during sleep mode, the
MCU wakes up and executes from the Reset Vector.
Note that if a level-triggered interrupt is used for wake-up from Power-down, the low
level must be held for a time longer than the reset delay Time-out period (t
TOUT
). Other-
wise, the device will not wake up.
Table 7. Interrupt 1 Sense Control
ISC11 ISC10 Description
0 0 The low level of INT1 generates an interrupt request.
0 1 Any logical change on INT1 generates an interrupt request.
1 0 The falling edge of INT1 generates an interrupt request.
1 1 The rising edge of INT1 generates an interrupt request.
Table 8. Interrupt 0 Sense Control
ISC01 ISC00 Description
0 0 The low level of INT0 generates an interrupt request.
0 1 Any logical change on INT0 generates an interrupt request.
1 0 The falling edge of INT0 generates an interrupt request.
1 1 The rising edge of INT0 generates an interrupt request.