C8051F50x-F51x
20.5. Port Match
Port match functionality allows system events to be triggered by a logic value change on P0, P1, P2 or P3.
A software controlled value stored in the PnMATCH registers specifies the expected or normal logic values
of P0, P1, P2, and P3. A Port mismatch event occurs if the logic levels of the Port’s input pins no longer
match the software controlled value. This allows Software to be notified if a certain change or pattern
occurs on P0, P1, P2, or P3 input pins regardless of the XBRn settings.
The PnMASK registers can be used to individually select which of the port pins should be compared
against the PnMATCH registers. A Port mismatch event is generated if (Pn & PnMASK) does not equal
(PnMATCH & PnMASK), where n is 0, 1, 2 or 3
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 20.4. P0MASK: Port 0 Mask Register
Bit
Name
Type
Reset
7
6
5
4
3
2
1
0
P0MASK[7:0]
R/W
0
0
0
0
0
0
0
0
SFR Address = 0xF2; SFR Page = 0x00
Bit
Name
7:0
P0MASK[7:0]
Port 0 Mask Value.
Function
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.
SFR Definition 20.5. P0MAT: Port 0 Match Register
Bit
Name
Type
Reset
7
6
5
4
3
2
1
0
P0MAT[7:0]
R/W
1
1
1
1
1
1
1
1
SFR Address = 0xF1; SFR Page = 0x00
Bit
Name
7:0
P0MAT[7:0]
Port 0 Match Value.
Function
Match comparison value used on Port 0 for bits in P0MAT which are set to 1.
0: P0.n pin logic value is compared with logic LOW.
1: P0.n pin logic value is compared with logic HIGH.
Rev. 1.1
187
SILABS [ SILICON LABORATORIES ]
