DS80C310

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PIN DESCRIPTION

PIN

PDIP

PLCC

TQFP

NAME

FUNCTION

Port 1 (I/O). Port 1 functions as both an 8-bit bidirectional I/O port

and an alternate functional interface for Timer 2 I/O and new

external interrupts. The reset condition of Port 1 is with all bits at

logic 1. In this state, a weak pullup holds the port high. This

condition also serves as an input mode, since any external circuit

that writes to the port overcomes the weak pullup. When software

writes a 0 to any port pin, the DS80C310 activates a strong pulldown

that remains on until either a 1 is written or a reset occurs. Writing a

1 after the port has been at 0 causes a strong transition driver to turn

on, followed by a weaker sustaining pullup. Once the momentary

strong driver turns off, the port once again becomes the output high

(and input) state. The alternate modes of Port 1 are outlined as

follows:

PIN

PDIP

PLCC

TQFP

PORT

ALTERNATE

FUNCTION

1

2

40

P1.0

T2

External I/O for

Timer/Counter 2

2

3

41

P1.1

T2EX

Timer/Counter 2

Capture/Reload

Trigger

3

4

42

P1.2

—

DS80C320 has a serial

port RXD

4

5

43

P1.3

—

DS80C320 has a serial

port TXD

5

6

44

P1.4

INT2

External Interrupt 2

(Positive Edge Detect)

6

7

1

P1.5

INT3

External Interrupt 3

(Negative Edge

Detect)

7

8

2

P1.6

INT4

External Interrupt 4

(Positive Edge Detect)

1–8

2–9

40–44,

1, 2, 3

P1.0–P1.7

8

9

3

P1.7

INT5

External Interrupt 5

(Negative Edge

Detect)

9

10

4

RST

Reset (Input). The RST input pin contains a Schmitt voltage input to

recognize external active-high reset inputs. The pin also employs an

internal pulldown resistor to allow for a combination of wired-OR

external reset sources.