GMS77C1000/GMS77C1001

6

July. 2001 Ver. 1.1

5. PIN FUNCTION

RESET: Reset the MCU.

the internal main clock operating circuit.

RA0~RA3: RA is an 4-bit, CMOS, bidirectional I/O port.

RA pins can be used as outputs or inputs according to “0”

or “1” written the their Port Direction Register(TRISA).

RB0~RB7: RB is a 8-bit, CMOS, bidirectional I/O port.

RB pins can be used as outputs or inputs according to “0”

or “1” written the their Port Direction Register(TRISB).

EC0: EC0 is an external clock input to Timer0. It should

sumption.

Legend : I =input, O = output, I/O = input/output, P = power, - = Not used, TTL = TTL input, ST = Schmitt Trigger input

PIN NAME

DIP, SOP

Pin No.

SSOP

Pin No.

In/Out

Input

Levels

Function

14

15,16

P-

Supply voltage

55,6

P-

Circuit ground

RESET

44

IST

Reset signal input/programming voltage input. This pin is an active low

avoid unintended entering of programming mode.

16

18

IST

Oscillator crystal input/external clock source input

15

17

O-

Oscillator crystal output. Connects to crystal or resonator in crystal oscilla-

RA0

17

19

I/O

TTL

4-bit bi-directional I/O ports

RA1

18

20

I/O

TTL

RA2

1

1

I/O

TTL

RA3

2

2

I/O

TTL

RB0

6

7

I/O

TTL

8-bit bi-directional I/O ports

RB1

7

8

I/O

TTL

RB2

8

9

I/O

TTL

RB3

9

10

I/O

TTL

RB4

10

11

I/O

TTL

RB5

11

12

I/O

TTL

RB6

12

13

I/O

TTL

RB7

13

14

I/O

TTL

EC0

3

3

IST

current consumption.

TABLE 5-1 PINOUT DESCRIPTION