C8051F336_08 Datasheet, PDF (129/227 Pages) Silicon Laboratories – Mixed-Signal Byte-Programmable EPROM MCU

C8051F336/7/8/9
20.5. Port Match
Port match functionality allows system events to be triggered by a logic value change on P0 or P1. A soft-
ware controlled value stored in the PnMATCH registers specifies the expected or normal logic values of P0
and P1. A Port mismatch event occurs if the logic levels of the Port’s input pins no longer match the soft-
ware controlled value. This allows Software to be notified if a certain change or pattern occurs on P0 or P1
input pins regardless of the XBRn settings.
The PnMASK registers can be used to individually select which P0 and P1 pins should be compared
against the PnMATCH registers. A Port mismatch event is generated if (P0 & P0MASK) does not equal
(P0MATCH & P0MASK) or if (P1 & P1MASK) does not equal (P1MATCH & P1MASK).
A Port mismatch event may be used to generate an interrupt or wake the device from a low power mode,
such as IDLE or SUSPEND. See the Interrupts and Power Options chapters for more details on interrupt
and wake-up sources.
SFR Definition 20.3. P0MASK: Port 0 Mask Register
Bit
7
6
5
4
3
2
1
0
Name
P0MASK[7:0]
Type
R/W
Reset
0
0
0
0
0
0
0
0
SFR Address = 0xFE
Bit
Name
7:0 P0MASK[7:0]
Function
Port 0 Mask Value.
Selects P0 pins to be compared to the corresponding bits in P0MAT.
0: P0.n pin logic value is ignored and cannot cause a Port Mismatch event.
1: P0.n pin logic value is compared to P0MAT.n.
Rev.1.0
129