TMP91C824
91C824-59
2008-02-20
3.5.3
Port 5 (P54 to P56)
Port 5 is an 3-bit general-purpose I/O port. I/O is set using control register P5CR and
P5FC. Resetting resets all bits of the output latch P5 to 1, the control register P5CR and
the function register P5FC to 0 and sets P54 to P56 to input mode with pull-up resistor.
In addition to functioning as a general-purpose I/O port, port 5 also functions as I/O for
the CPU’s control/status signal.
Figure 3.5.4 Port 5 (P55)
BUSAK
Function control
(on bit basis)
S
Output
latch
P55(
BUSAK
)
Selec
tor
Int
erna
l dat
a
bu
s
Direction control
(on bit basis)
P5CR write
P-ch (Programmable pull up)
Reset
P5FC write
P5 write
Output buffer
P5 read
S
A
B