Toshiba TMP91C815F Data Book page 74

3.5.9 Port B (PB0 to PB6)
Port B0 to PB6 is a 7-bit general-purpose I/O port. Each bit can be set individually for input or output.
Resetting sets Port B to be an input port.
In addition to functioning as a general-purpose I/O port, Port B0 has clock input terminal TA0IN of 8
bits timer 0, and port B1, B2 each has facility of 8 bits timer listing TA1OUT, TA3OUT terminal. And,
port B3 to B6 has each external interruption input facility of INT0 to INT3. Edge selection of external
interruption is establishes by IIMC register in the interrupt controller.
Timer output function and external interrupt function can be enabled by writing "1" to the
corresponding bits in the Port B Function Register (PBFC). Resetting resets all bits of the registers PBCR
and PBFC to "0", and sets all bits to be input ports.
(1) PB0 to PB2
Direction Control
Output latch
TA0IN
Function control
Timer F/F OUT
TA1OUT : Timer A1
TA3OUT : Timer A3
Reset
(on bits basis)
PBCR write
S
S
B
PB write
Selector
PB read
A
Reset
Direction Control
(on bits basis)
PBCR Write
(on bits basis)
PBFC Write
S
Output latch
A S
PB Write
Selector
B
B
Selector
PB read
A
S
Figure 3.5.24(1) Port B0 to B2
91C815-71
TMP91C815
PB0 (TA0IN)
PB1 (TA1OUT)
PB2 (TA3OUT)