MB90F654A FUJITSU [Fujitsu Component Limited.], MB90F654A Datasheet - Page 29

• Manufacturer Part Number: MB90F654A
• Description: 16-bit Proprietary Microcontroller
• Manufacturer: FUJITSU [Fujitsu Component Limited.]

1. Parallel Ports
(1) I/O Ports
PERIPHERAL RESOURCES
Each port pin can be specified as either an input or output by its corresponding direction register when the pin
is not set for use by a peripheral. When a port is set as an input, reading the data register always reads the value
corresponding to the pin level. When a port is set as an output, reading the data register reads the data register
latch value. The same applies when reading using a read-modify-write instruction.
When used as control outputs, reading the data register reads the control output value, irrespective of the direction
register value.
Note that if a read-modify-write instruction (set bit or similar instruction) is used to set output data in the data
register before switching a pin from input to output, the instruction reads the input level at the pin and not the
data register latch value.
• Block diagram
Data register read
Data register write
Direction register write
Direction register read
Direction register
Data register
MB90650A Series
Pin
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