AT89S51-24JC Atmel, AT89S51-24JC Datasheet - Page 5
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AT89S51-24JC
Manufacturer Part Number
AT89S51-24JC
Description
IC 8051 MCU 4K FLASH 44PLCC
Manufacturer
Atmel
Series
89Sr
Datasheet
1.AT89S51-24JU.pdf
(31 pages)
Specifications of AT89S51-24JC
Core Processor
8051
Core Size
8-Bit
Speed
24MHz
Connectivity
UART/USART
Peripherals
WDT
Number Of I /o
32
Program Memory Size
4KB (4K x 8)
Program Memory Type
FLASH
Ram Size
128 x 8
Voltage - Supply (vcc/vdd)
4 V ~ 5.5 V
Oscillator Type
Internal
Operating Temperature
0°C ~ 70°C
Package / Case
44-PLCC
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Eeprom Size
-
Data Converters
-
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
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Manufacturer:
ATM
Quantity:
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Company:
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AT89S51-24JC
Manufacturer:
ATMEL
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Manufacturer:
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Quantity:
20 000
4.7
4.8
4.9
4.10
2487D–MICRO–6/08
RST
ALE/PROG
PSEN
EA/VPP
nal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low
will source current (I
Port 3 receives some control signals for Flash programming and verification.
Port 3 also serves the functions of various special features of the AT89S51, as shown in the fol-
lowing table.
Reset input. A high on this pin for two machine cycles while the oscillator is running resets
the device. This pin drives High for 98 oscillator periods after the Watchdog times out. The DIS-
RTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of
bit DISRTO, the RESET HIGH out feature is enabled.
Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during
accesses to external memory. This pin is also the program pulse input (PROG) during Flash
programming.
In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be
used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped dur-
ing each access to external data memory.
If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set,
ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high.
Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.
Program Store Enable (PSEN) is the read strobe to external program memory.
When the AT89S51 is executing code from external program memory, PSEN is activated twice
each machine cycle, except that two PSEN activations are skipped during each access to exter-
nal data memory.
External Access Enable. EA must be strapped to GND in order to enable the device to fetch
code from external program memory locations starting at 0000H up to FFFFH. Note, however,
that if lock bit 1 is programmed, EA will be internally latched on reset.
Port Pin
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
IL
) because of the pull-ups.
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 1 external input)
WR (external data memory write strobe)
RD (external data memory read strobe)
AT89S51
5