25
AT90S/LS2323/2343
1004D–09/01
General Interrupt Flag
Register – GIFR
• Bit 7 – Res: Reserved Bit
This bit is a reserved bit in the AT90S2323/2343 and always reads as zero.
• Bit 6 – INTF0: External Interrupt Flag0
When an edge on the INT0 pin triggers an interrupt request, the corresponding interrupt
flag, INTF0 becomes set (one). If the I-bit in SREG and the corresponding interrupt
enable bit, INT0 in GIMSK, is set (one), the MCU will jump to the interrupt vector. The
flag is cleared when the interrupt routine is executed. Alternatively, the flag is cleared by
writing a logical “1” to it. This flag is always cleared when INT0 is configured as level
interrupt.
• Bits 5..0 – Res: Reserved Bits
These bits are reserved bits in the AT90S2323/2343 and always read as zero.
Timer/Counter Interrupt Mask
Register – TIMSK
• Bits 7..2 – Res: Reserved Bits
These bits are reserved bits in the AT90S2323/2343 and always read zero.
• Bit 1 – TOIE0: Timer/Counter0 Overflow Interrupt Enable
When the TOIE0 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter0 Overflow interrupt is enabled. The corresponding interrupt (at vector
$002) is executed if an overflow in Timer/Counter0 occurs, i.e., when the Overflow Flag
(Timer/Counter0) is set (one) in the Timer/Counter Interrupt Flag Register (TIFR).
• Bit 0 – Res: Reserved Bit
This bit is a reserved bit in the AT90S2323/2343 and always reads as zero.
Timer/Counter Interrupt FLAG
Register – TIFR
• Bits 7..2 – Res: Reserved Bits
These bits are reserved bits in the AT90S2323/2343 and always read zero.
• Bit 1 – TOV0: Timer/Counter0 Overflow Flag
The bit TOV0 is set (one) when an overflow occurs in Timer/Counter0. TOV0 is cleared
by hardware when executing the corresponding interrupt handling vector. Alternatively,
TOV0 is cleared by writing a logical “1” to the flag. When the SREG I-bit and TOIE0
(Timer/Counter0 Overflow Interrupt Enable) and TOV0 are set (one), the
Timer/Counter0 Overflow Interrupt is executed.
Bit 7 6 5 4 3 2 1 0
$3A ($5A) – INTF0 –– ––––GIFR
Read/Write R R/W R R R R R R
Initial Value 0 0 0 0 0 0 0 0
Bit 7 6 5 4 3 2 1 0
$39 ($59) –––– – –TOIE0 – TIMSK
Read/Write R R R R R R R/W R
Initial Value 0 0 0 0 0 0 0 0
Bit 7 6 5 4 3 2 1 0
$38 ($58) –– ––––TOV0 – TIFR
Read/Write R R R R R R R/W R
Initial Value 0 0 0 0 0 0 0 0
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