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The external interrupt 2 (INT2/) can be either positive or negative transition-activated depending
on bit I2FR in register T2CON (see figure 8-5). The flag that actually generates this interrupt is bit
IEX2 in register IRCON. lf an interrupt 2 is generated, flag IEX2 is cleared by hardware when the
service routine is vectored too.
Figure 8-5
Special Function Register T2CON (Address 0C8 H )
0CF H
0C8 H
T2PS
These bits are not used for interrupt control.
Bit
Function
I2FR
External interrupt 2 falling/rising edge flag. When set, the interrupt 2 request flag
IEX2 will be set on a positive transition at pin P1.4/INT2. I2FR = 0 specifies
external interrupt 2 to be negative-transition activated.
I3FR
External interrupt 3 falling/rising edge flag. When set, the interrupt 3 request flag
IEX3 will be set on a positive transition at pin P1.0/INT3. I3FR = 0 specifies
external interrupt 3 to be negative-transition active.
Like the external interrupt 2, the external interrupt 3 (INT3) can be either positive or negative
transition-activated, depending on bit I3FR in register T2CON. The flag that actually generates this
interrupt is bit IEX3 in register IRCON. In addition, this flag will be set if a compare event occurs at
pin P1.0/INT3/CC0, regardless of the compare mode established and the transition at the
respective pin. The flag IEX3 is cleared by hardware when the service routine is vectored too.
The external interrupts 4 (INT4), 5 (INT5), 6 (INT6) are positive transition-activated. The flags that
actually generate these interrupts are bits IEX4, IEX5, and IEX6 in register IRCON (see figure 8-6).
In addition, these flags will be set if a compare event occurs at the corresponding output pin P1.1/
INT4/CC1, P1.2/INT5/CC2, and P1.3/INT6/CC3, regardless of the compare mode established and
the transition at the respective pin. When an interrupt is generated, the flag that generated it is
cleared by the on-chip hardware when the service routine is vectored too.
Semiconductor Group
0CE H
0CD H 0CC H 0CB H
I3FR
I2FR
T2R1
0CA H
0C9 H
T2R0
T2CM
*
118
Interrupt System
0C8 H
T2I1
T2I0
T2CON
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