DMC73CE167 データシートの表示（PDF） - Daewoo Semiconductor

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DMC73CE167

8Bit Single Chip Microcontroller

Daewoo Semiconductor 

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8Bit Single Chip Microcontroller

DMC73C167

5. FUNCTION

5.1 Input/Output Ports

The DMC73C167 has 28 I/O pins organized as four parallel ports labeled

A, B, C and D. Each port is mapped into 4- to 8-bit data value resiters in the peripheral file (PF).

The data value registers are usually called APORT, BPORT, CPORT and DPORT in a program.

Ports A, C and D are implemented as bidirectional I/O ports.

Port B is an open-drain output only port with a 12 V buffer (B0-B3)and 12mA current drive

capability (B4-B7).

Each bidirectional port (that is, Port A, C and D) has a corresponding data direction register

(DDR) that programs each I/O pin as an input or output pin. A bit set to 1 in the DDR will

cause the corresponding pin to be an output pin, while a 0 in the DDR will turn the pin into

a high-impedance input pin. Upon RESET, the DDR filp-flop registers are set to 0 by the

on-chip circuitry, forcing them to become inputs. Also upon RESET, the output data registers

of the output only port (that is, Port B) are set to 1 by the on-chip circuitry. And, other output

data registers are indeterminated data set.

After RESET, if 1s are writtern to the DDR register sometime before the output data register

is changed, then the corresponding I/O pins will output a 1. For this reason, it is good

practice to load the output data registers of Ports A, C and D with the desired value before

any bits are configured as outputs. In addition, DMC73C167 has several mask options

related to the I/O pins such as pull-up resistors. Those I/O pins are individually configurable

at the masking stage. For a detailed description of the I/O pins in the DMC73C167,

see table 3-2.

5.1.1 A Port

Pins A0 to A7 of A port are bidirectional I/O ports and several hardware-related functions are

interfaced with the CPU through this port. Pin A0 can be used as an analog input for the on-

chip A/D converter. Pin A1 and A2 can be used for the event counter input of Timer 1 and

Timer 2, respectively. Pin A3, A4 and A5 can be used for the Schmitt-buffered external interrupt

input for INT1, INT3_0, and INT5_0, respectively.

Reading the port - A data register (P6) returns each value at the A0 - A7 pins if the

corresponding DDR bit is set to 0 and returns each output buffer register value if the DDR

bit is 1. The user can specify internal pull-up (5V) resistor insertion or not selectively for port

A pins (mask option).

Table 5-1. P7 0107h ADDR A Port Direction

Bit

7

6

5

4

3

2

1

0

R

W

ADDR7 ADDR6 ADDR5 ADDR4 ADDR3 ADDR2 ADDR1 ADDR0

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