CP80S54E ETC2 [List of Unclassifed Manufacturers], CP80S54E Datasheet - Page 15

• Manufacturer Part Number: CP80S54E
• Description: EPROM/ROM-Based 8-Bit Microcontroller Series
• Manufacturer: ETC2 [List of Unclassifed Manufacturers]

2.2 I/O Ports
Port A and port B are bi-directional tri-state I/O ports. Port A and Port B are 8-pin I/O ports. Port C is a general
purpose register. Please note that IOA5 is an input only pin.
All I/O pins (IOA<7:0> and IOB<7:0>) have data direction control registers (IOSTA, IOSTB) which can configure
these pins as output or input.
IOB<7:0> have its corresponding pull-high control bits (PHCON register) to enable the weak internal pull-high. The
weak pull-high is automatically turned off when the pin is configured as an output pin.
IOA<3:0> and IOB<3:0> have its corresponding pull-down control bits (PDCON register) to enable the weak internal
pull-down. The weak pull-down is automatically turned off when the pin is configured as an output pin.
IOB<7:0> have its corresponding open-drain control bits (ODCON register) to enable the open-drain output when
these pins are configured to be an output pin.
IOA0 and IOA1 are the R-option pins enabled by setting the ROC bit (PCON<4>). When the R-option function is
used, it is recommended that IOA0 and IOA1 are used as output pins, and read the status of IOA0 and IOA1 before
these pins are configured to be an output pin.
IOB<7:0> also provides the input change interrupt/wake-up function. Each pin has its corresponding input change
interrupt/wake-up enable bits (WUCON) to select the input change interrupt/wake-up source.
The IOB0 is also an external interrupt input signal by setting the EIS bit (PCON<6>). In this case, IOB0 input change
interrupt/wake-up function will be disabled by hardware even if it is enabled by software.
FIGURE 2.3: Block Diagram of I/O PINs
IOA7, IOA6, IOA4 ~ IOA0 :
IOA5 :
WR PORT
RD PORT
RD PORT
IOST R
Data bus
Data bus
Pull-down is not shown in the figure
> EN
> EN
D
D
Latch
DATA
Latch
IOST
Q
Q
Q
Q
CP80S54/56
I/O PIN
I/O PIN
Rev0.1 Nov 30, 2005
P.15/CP80S54/S56