1 port po (p07 to poo), Toshiba – Toshiba TMP87CP24AF User Manual
Page 54
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TOSHIBA
TMP87CM24A/P24A
2.2.1 Port PO (P07 to POO)
Port PO is an
8
-bit general-purpose input/output port which can be configured as either an input or an
output in one-bit unit under software control. Input/output mode is specified by the corresponding bit
in the port PO input/output control register (POCR). Port PO is configured as an input if its corresponding
POCR bit is cleared to "0", and as an output if its corresponding POCR bit is set to "1
During reset, POCR is initialized to "0", which configures port PO as input. The PO output latches are also
initialized to "
0
".
POi
Output latch
PO
(OOOO
h
)
R/W
POCR
(OOOA
h
)
7
6
5
4
3
2
1
0
P07
P06
P05
P04
P03
P02
POI
POO
7
6
5
4
3
2
1
0
Notel: i = 7to0
Note2 : STOP: bit 7 ofSYSCR 1
Notes : OUTEN: bit 4 ofSYSCR2
(Initial value :
0000 0000)
(Initial value :
0000 0000)
POCR
I/O control for port PO
0 : Input mode
Write
(Set for each bit individually)
1 : Output mode
only
Figure 2-3. Port PO and POCR
Example : Setting the upper 4 bits of port PO as an input port and the lower 4 bits as an output
port (Initial output data are
1010
b
).
LD
(PO), 0000101 OB
; Sets initial data to PO output latches
LD
(POCR), 00001111B
; Sets the port PO input/output mode
Note 1
Note 2
Ports set to the input mode read the pin states. When input pin and output pin exist in port
PO together, the contents of the output latch of ports set to the input mode may be rewritten
by executing the bit manipulation instructions. Pins set to the output mode read a value of
the output latch.
The POCR is a write-only register. It can not be operated by the read-mod ify-write instruction
(Bit manipulation instructions of SET, CLR, etc. and Arithmetic instructions of AND, OR, etc.)
3
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24-54
2002
-
10-03