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HARDWARE CONFIGURATION
2-30
I/O PORTS
(4) P70 and P71: CMOS-type input ports
•
Input port operation
The PDR can only be read and the value of the pin is always read.
Note: When the dual-circuit clock option is selected, P71 and P70 serve as
X1A and X0A pins.
•
State when reset
The PDR cannot be initialized by reset.
Internal data bus
PDR read
PDR
Oscillation circuit
Pin
Option
Fig. 2.14 Ports 70 and 71
(5) P30 and P32 to P35 and P17: CMOS type I/O ports
(also used as resource I/O)
•
Switching input and output
This port has a data-direction register (DDR) and a port-data register
(PDR) for each bit. Input and output can be set independently for each bit.
The pin with the DDR set to 1 is set to output, and the pin with the DDR set
to 0 is set to input.
•
Operation for output port (DDR = 1)
The value written at the PDR is output to the pin when the DDR is set to 1.
When the PDR is read, usually, the value of the pin is read instead of the
contents of the output latch. However, when the Read Modify Write
instruction is executed, the contents of the output latch are read irrespec-
tive of the DDR setting conditions. Therefore, the bit-processing instruc-
tion can be used even if input and output are mixed with each other. When
data is written to the PDR, the written data is held in the output latch irre-
spective of the DDR setting conditions.
•
Operation for input port (DDR = 0)
When used as the input port, the output impedance goes High. There-
fore, when the PDR is read, the value of the pin is read.
•
Resource output operation
When using as the resource output, setting is performed by the resource
output enable bit. (See the description of each resource.) Since the re-
source output enable bit has priority in switching input and output, even if
the DDR is set to 0, any bit is set as the resource output when output is
enabled at each resource. Even if the output from each resource is en-
abled, the read value of the port is effective, so the resource output value
can be checked.
Summary of Contents for F2MC-8L Series
Page 121: ...INSTRUCTIONS 4 7 4 5 F2MC 8L FAMILY INSTRUCTION MAP ...
Page 123: ...5 MASK OPTIONS ...
Page 125: ...APPENDIX ...