GMS97C2051 Datasheet, PDF (3/39 Pages) Hynix Semiconductor – 8-Bit CMOS Microcontorller

8-Bit CMOS Microcontorller
GMS97C2051/L2051
Pin Description
Input to the inverting oscillator amplifier and input to
the internal clock operating circuit.
Vcc
Supply voltage.
XTAL2
Output from the inverting oscillator amplifier.
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 (I_IL) because of the inter-
nal pullups.
Port 1 also receives code data during EPROM pro-
gramming and program verification.
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
C2
XTAL2
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
(I_IL) because of the pullups.
Port 3 also serves the functions of various special fea-
ture of the GMS97C2051 as listed below:
C1
XTAL1
GND
Notes: C1, C2 = 30pF
10pF for Crystals
( include stray capacitance )
Port Pin
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
Alternate Functions
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 )
Figure 2. External Clock Drive Configuration
NC
XTAL2
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.
EXTERNAL
OSCILLATOR
SIGNAL
XTAL1
GND
XTAL1
3
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