PIC16F87XA
FIGURE 4-7:
PORTC BLOCK DIAGRAM
(PERIPHERAL OUTPUT
OVERRIDE) RC<4:3>
4.3
PORTC and the TRISC Register
PORTC is an 8-bit wide, bi-directional port. The corre-
sponding data direction register is TRISC. Setting a
TRISC bit (= 1) will make the corresponding PORTC
pin an input (i.e., put the corresponding output driver in
a Hi-Impedance mode). Clearing a TRISC bit (= 0) will
make the corresponding PORTC pin an output (i.e., put
the contents of the output latch on the selected pin).
Port/Peripheral Select(2)
Peripheral Data Out
Data Bus
0
VDD
D
Q
P
I/O
WR
Port
pin(1)
1
PORTC is multiplexed with several peripheral functions
(Table 4-5). PORTC pins have Schmitt Trigger input
buffers.
When the I2C module is enabled, the PORTC<4:3>
pins can be configured with normal I2C levels, or with
SMBus levels, by using the CKE bit (SSPSTAT<6>).
Q
CK
Data Latch
D
Q
Q
WR
TRIS
CK
N
TRIS Latch
Vss
When enabling peripheral functions, care should be
taken in defining TRIS bits for each PORTC pin. Some
peripherals override the TRIS bit to make a pin an out-
put, while other peripherals override the TRIS bit to
make a pin an input. Since the TRIS bit override is in
effect while the peripheral is enabled, read-modify-
write instructions (BSF, BCF, XORWF) with TRISC as
the destination, should be avoided. The user should
refer to the corresponding peripheral section for the
correct TRIS bit settings.
RD
TRIS
Schmitt
Trigger
Peripheral
OE(3)
Q
D
Schmitt
Trigger
EN
with
RD
Port
SMBus
Levels
0
SSPl Input
1
CKE
SSPSTAT<6>
FIGURE 4-6:
PORTC BLOCK DIAGRAM
(PERIPHERAL OUTPUT
OVERRIDE) RC<2:0>,
RC<7:5>
Note 1: I/O pins have diode protection to VDD and VSS.
2: Port/Peripheral Select signal selects between port data
and peripheral output.
3: Peripheral OE (output enable) is only activated if
Peripheral Select is active.
Port/Peripheral Select(2)
Peripheral Data Out
Data Bus
VDD
P
0
1
D
Q
Q
I/O
WR
pin(1)
Port
CK
Data Latch
D
Q
Q
WR
TRIS
CK
N
TRIS Latch
VSS
RD
TRIS
Schmitt
Trigger
Peripheral
OE(3)
Q
D
EN
RD
Port
Peripheral Input
Note 1: I/O pins have diode protection to VDD and VSS.
2: Port/Peripheral Select signal selects between port
data and peripheral output.
3: Peripheral OE (output enable) is only activated if
Peripheral Select is active.
DS39582A-page 44
AdvanceInformation
2001 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
