GMS97C2051 datasheet(3/39 Pages) HYNIX

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8-Bit CMOS Microcontorller

GMS97C2051/L2051

HYUNDAI MicroElectonics

Pin Description

Vcc

Supply voltage.

GND

Ground.

Port 1

Port 1 is an 8-bit bidirectional I/O port.

Port pins P1.2

to P1.7 provide internal pullups.

P1.0 and P1.1 re-

quire external pullups.

P1.0 and P1.1 also serve as the

positive input (AIN0) and the negative input (AIN1),

respectively, of the on-chip precision analog compara-

tor.

The Port 1 output buffers can sink 10mA and can

drive LED displays directly.

When 1s are written to

Port1 pins, they can be used as inputs.

When pins

P1.2 to P1.7 are used as inputs and are externally pulled

low, they will source current (IIL) because of the inter-

nal pullups.

Port 1 also receives code data during EPROM pro-

gramming and program verification.

Port3

Port 3 pins P3.0 to P3.5, P3.7 are seven bidirectional

I/O pins with internal pullups.

P3.6 is hard-wired as

an input to the output of the on-chip comparator and is

not accessible as a general purpose I/O pin.

The Port

3 output buffers can sink 10mA.

When 1s are written

to Port 3 pins they are pulled high by the internal pul-

lups and can be used as inputs.

As inputs, Port 3 pins

that are externally being pulled low will source current

(IIL) because of the pullups.

Port 3 also serves the functions of various special fea-

ture of the GMS97C2051 as listed below:

Port Pin

Alternate Functions

P3.0

P3.1

P3.2

P3.3

P3.4

P3.5

RXD ( serial input port )

TXD ( serial output port )

INT0 ( external interrupt 0 )

INT1( external interrupt 1 )

T0 ( timer 0 external input )

T1 ( timer 0 external input )

Port 3 also receives some control signals for EPROM

programming and programming verification.

RST

Reset input.

All I/O pins are reset to 1s as soon as

RST goes high.

Holding the RST pin high for two

machine cycles while the oscillator is running resets the

device.

This pin is also receives the 12.75V programming

supply voltage ( Vpp ) during EPROM programming.

XTAL1

Input to the inverting oscillator amplifier and input to

the internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

Recommended Oscillator Circuit

XTAL1 and XTAL2 are the input and output, respec-

tively, of an inverting amplifier which can be config-

ured for use as an on-chip oscillator, as shown in Fig-

ure 1. To drive the device from an external clock

source,

XTAL2 should be left unconnected while

XTAL1 is driven as shown in Figure 2.

Figure 1.

Oscillator Connections

XT AL 2

XT AL 1

GND

Notes: C1, C2 = 30pF

10pF for Crystals

( include stray capacitance )

Figure 2.

External Clock Drive Configuration

XTAL2

XTAL1

GND

EXTERNAL

OSCILLATOR

SIGNAL

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