Port 8 (P80 - P83) - Toshiba TLCS-90 Series Data Book

TOSHIBA TMP90C840
3.5.9
Port 8 (P8D - P83)
Port 8 is a 4-bit general-purpose I/O port (P8: memory address FFDOH),
with P80 to P82 intended only for the input and P83 only for the
output. The output latch of P83 is reset to "0", whereby the output
level turns to "L".
Port 8 also has the functions of interrupt request input, clock input
for a timer/event counter, and timer output.
(1) P80/INTO
P80 is a general-purpose input port, also used as the external
interrupt request input pin INTO. INTO allows the selection of either
an "H" level interrupt or rising edge interrupt by using the control
register (P8CR: Bit 0 of memory address FFDlH).
H
::l
rt
~
Read PS
::l
III
t-'
t::l
III
rt
III
tJj
~
en
(2) P8l/INTl/TI4
PSCR
Fig. 3.5 (15) Port P80/INTO
PSO/INTO
P8l is a general-purpose input port, also used as the external
interrupt request input pin INTI and the clock input pin TI4 for the
timer/event counter.
This port incorporates a zero-eros s detec tion circuit, and enab les
zero-cross detection by connecting an external capacitor. The zero-
cross detection can be disabled/enabled by using the control register
(P8CR: Bit 1 of memory address FFDIH). This control register is reset
to "0", making the zero-cross detection disabled.
(3) P82/INT2/TI5
Like P8l, P82 is a general-purpose input port, als a used as the
external interrupt request input pin INT2 and the clock input pin TIS
for the timer/ event counter. This port also contains a zero-cross
detection circuit, and disables/enables the zero-cross detection by
using the control register (P8CR: Bit 2 of memory address FFDIH).
When this control register is reset, the zero-cross detection is
disabled.
MPU90-70