• Bit 3 – ACIE: Analog Comparator Interrupt Enable
When the ACIE bit is set (one) and the I-bit in the Status Register is set (one), the Ana-
log Comparator Interrupt is activated. When cleared (zero), the interrupt is disabled.
• Bit 2 – Res: Reserved Bit
This bit is a reserved bit in the AT90S1200 and will always read as zero.
• Bits 1, 0 – ACIS1, ACIS0: Analog Comparator Interrupt Mode Select
These bits determine which comparator events trigger the Analog Comparator Interrupt.
The different settings are shown in Table 7.
Table 7. ACIS1/ACIS0 Settings
ACIS1
ACIS0
Interrupt Mode
0
0
1
1
0
1
0
1
Comparator Interrupt on Output Toggle
Reserved
Comparator Interrupt on Falling Output Edge
Comparator Interrupt on Rising Output Edge
Note:
When changing the ACIS1/ACIS0 bits, the Analog Comparator Interrupt must be dis-
abled by clearing its Interrupt Enable bit in the ACSR register. Otherwise, an interrupt
can occur when the bits are changed.
28
AT90S1200
0838H–AVR–03/02
ATMEL [ ATMEL ]
