Toshiba TMP91C815F Data Book page 77

3.5.10 Port C (PC0 to PC5)
Port C0 to C5 are 6-bit general-purpose I/O ports. Each bit can be set individually for input or
output. Resetting sets PC0 to PC5 to be an input ports. It also sets all bits of the output latch register
to "1".
In addition to functioning as general-purpose I/O port pins, PC0 to PC5 can also function as the I/O
for serial channels 0 and 1. A pin can be enabled for I/O by writing "1" to the corresponding bit of
the Port C Function Register (PCFC).
Resetting resets all bits of the registers PCCR and PCFC to 0 and sets all pins to be input ports .
(1) Port C0, C3 (TXD0/TXD1)
As well as functioning as I/O port pins, port C0 and C3 can also function as serial channel TXD
output pins. In case of use TXD0/TXD1, it is possible to logical invert by setting the register
PC<PC0,PC3>.
And port C0 to C3 have a programmable open drain function which can be controlled by the
register PCODE<ODEPC0, ODEPC3>.
Ditection control
(On bit basis)
PCCR write
Function control
(On bit basis)
PCFC write
S
Output latch
PC write
TXD0, TXD1
PC Read
Reset
A S
Selector
Logical invert
B
S B
Selector
A
Figure 3.5.26(1) Port C0 and C3
91C815-74
PC0 (TXD0)
PC3 (TXD1)
Open-drain
set possible
PCODE<ODEPC0, C3>
TMP91C815