HT83C51 Honeywell Microelectronics & Precision Sensors, HT83C51 Datasheet - Page 3

• Manufacturer Part Number: HT83C51
• Description: IC MICROCONTROLLER 8K 40-DIP
• Manufacturer: Honeywell Microelectronics & Precision Sensors
• Series: HTMOS™r

Specifications of HT83C51

• Core Processor: MCS 51
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: EBI/EMI, UART/USART
• Peripherals: PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: Mask ROM
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -55°C ~ 225°C
• Package / Case: 40-CDIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

PIN DESCRIPTIONS
V DD : +5V Supply Voltage
V SS : Circuit Ground
Port 0 (P0.0 - P0.7): Port 0 is an 8-bit bidirectional I/O port.
If external Program and/or Data memory are used, port 0
cannot be used for general purpose I/O. During accesses
to external Program and Data memory Port 0 is used as the
low-order multiplexed address and data bus. In this mode,
Port 0 pins use strong internal pullups when emitting 1’s,
and are TTL compatible. If external Program and Data
memory are not used, Port 0 pins can be used as general
purpose I/O. When the Port pins have 1’s written to them
in I/O mode, the pins are floating and can be driven as
inputs. An external pullup is required to generate logic high
output in I/O mode.
Port 1 (P1.0 - P1.7): Port 1 is an 8-bit bidirectional I/O port
with internal pullups. The output buffers can drive TTL
loads. When the Port 1 pins have 1’s written to them, they
are pulled high by the internal pullups and can be used as
inputs in this state. As inputs, any pins that are externally
pulled low will source current because of the pullups. In
addition, Port 1 pins have the alternate uses shown in the
table below:
Port 2 (P2.0 - P2.7): Port 2 is an 8-bit bidirectional I/O port
with internal pullups. The output buffers can drive TTL
loads. When the Port 2 pins have 1’s written to them, they
are pulled high by the internal pullups and can be used as
inputs in this state. As inputs, any pins that are externally
pulled low will source current because of the pullups.
Port 2 is used as the high-order address byte during
accesses to external Program Memory and during accesses
to external Data Memory that use 16-bit addresses (i.e.
MOVX @DPTR). It uses strong internal pullups when
emitting 1’s in this mode. During accesses to external Data
Memory that use 8 bit addresses, Port 2 emits the contents
of the P2 SFR.
Port 3 (P3.0 - P3.7): Port 3 is an 8-bit bidirectional I/O port
with internal pullups. The output buffers can drive TTL
Port
Pin
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Name
T2EX
CEX0
CEX2
CEX3
CEX4
CEX1
ECI
T2
Alternate Function
External clock input to timer/ Clock out
Timer/Counter 2 Capture/Reload trigger and
direction control
External count input to PCA
External I/O for PCA capture/compare Module 0
External I/O for PCA capture/compare Module 1
External I/O for PCA capture/compare Module 2
External I/O for PCA capture/compare Module 3
External I/O for PCA capture/compare Module 4
3
loads. When the Port 3 pins have 1’s written to them, they
are pulled high by the internal pullups and can be used as
inputs in this state. As inputs, any pins that are externally
pulled low will source current because of the pullups. In
addition, Port 3 pins have the alternate uses shown in the
table below:
RST: Reset input. A high on this input for 2 or more
oscillator periods while the oscillator is running resets the
device. All ports and Special Function Registers will be
reset to their default conditions. Internal data memory is
undefined after reset. Program execution will begin within
12 oscillator periods (one machine cycle) after the RST
signal is brought low. RST contains an internal pulldown
resistor to allow implementing power-up reset with only an
external capacitor.
ALE: Address Latch Enable. The ALE output is a pulse for
latching the low byte of the address during accesses to
external memory. In normal operation the ALE pulse is
output every 6th oscillator cycle and may be used for
external timing or clocking. However, during each access
to external Data Memory (MOVX instruction), one ALE
pulse is skipped. If desired, ALE operation can be disabled
by setting bit 0 of SFR 8EH. When this bit is set, ALE is
active only during a MOVX instruction. Otherwise, the pin
is held low. When ALE is disabled, program execution
must be limited to the internal 8K program ROM.
PSENn: Program Store Enable. This active low signal is
the read strobe to the external program memory. PSENn
is activated every 6th oscillator cycle except that 2 PSENn
activations are skipped during external data memory
accesses.
EAn: External Access Enable. The EAn pin must be
strapped to VSS for the HT51 to fetch code from external
Program Memory locations 0000H to 1FFFH. The EAn pin
must be strapped to VDD for internal program execution
from memory locations 0000H to 1FFFH.
XTAL1: Input to the inverting oscillator amplifier.
XTAL2: Output from the inverting oscillator amplifier.
Port Pin
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
Alternate Name Alternate Function
INT0n
INT1n
RXD
TXD
WRn
RDn
T0
T1
Serial port input
Serial port output
External interrupt 0
External interrupt 1
External clock input for Timer 0
External clock input for Timer 1
External Data Memory write strobe
External Data Memory read strobe
HT83C51