AT89C52 – 8 bit Microcontroller belongs to Atmel’s 8051 families. AT89C52 has 8KB of Flash programmable and erasable read-only memory (PEROM) and 256 bytes of RAM. it has an endurance of 1000 Write/Erase cycles which means that it can be erased and programmed to a maximum of 1000 times.
In 40 pin AT89C52, there are four ports designated as P1, P2, P3 and P0. All these ports are 8-bit bi-directional ports i.e., they can be used as both input and output ports. Except P0 which needs external pull-ups, rest of the ports have internal pull-ups. When 1s are written to these port pins, they are pulled high by the internal pull-ups and can be used as inputs. These ports are also bit addressable and so their bits can also be accessed individually.
Port P0 and P2 are also used to provide low byte and high byte addresses, respectively, when connected to an external memory. Port 3 has multiplexed pins for special functions like serial communication, hardware interrupts, timer inputs and read/write operation from external memory. AT89C52 has an inbuilt UART for serial communication. It can be programmed to operate at different baud rates. Including two timers hard interrupts, it has a total of six interrupts.
Features:
Compatible with MCS® -51Products
8K Bytes of In-System Programmable (ISP) Flash Memory – Endurance: 10,000 Write/Erase Cycles
4.0V to 5.5V Operating Range
Fully Static Operation: 0 Hz to 33 MHz
Three-level Program Memory Lock
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Eight Interrupt Sources
Full Duplex UART Serial Channel
Low-power Idle and Power-down Modes
Interrupt Recovery from Power-down Mode
Watchdog Timer
Dual Data Pointer
Power-off Flag
Fast Programming Time
Flexible ISP Programming (Byte and Page Mode)
Green (Pb/Halide-free) Packaging Option
AT89S52 Pin Configuration
Pin Number
Pin Name
Description
1
P1.0 (T2)
Timer/Counter or 0th GPIO pin of PORT 1
2
P1.1 (T2.EX)
Timer/Counter/External Counter or 1st GPIO pin of PORT 1
3
P1.2
2nd GPIO pin of PORT 1
4
P1.3
3rd GPIO pin of PORT 1
5
P1.4
4th GPIO pin of PORT 1
6
P1.5 (MOSI)
MOSI for in System Programming or 5th GPIO pin of PORT 1
7
P1.6 (MISO)
MISO for in System Programming or 6th GPIO pin of PORT 1
8
P1.7 (SCK)
SCK for in System Programming or 7th GPIO pin of PORT 1
9
RST
Making this pin high will reset the Microcontroller
10
P3.0 (RXD)
RXD Serial Input or 0th GPIO pin of PORT 3
11
P3.1 (TXD)
TXD Serial Output or 1st GPIO pin of PORT 3
12
P3.2 (INT0’)
External Interrupt 0 or 2nd GPIO pin of PORT 3
13
P3.3 (INT1’)
External Interrupt 1 or 3rd GPIO pin of PORT 3
14
P3.4 (T0)
Timer 0 or 4th GPIO pin of PORT 3
15
P3.5 (T1)
Timer 1 or 5th GPIO pin of PORT 3
16
P3.6 (WR’)
Memory Write or 6th GPIO pin of PORT 3
17
P3.7 (RD’)
Memory Read or 7th GPIO pin of PORT 3
18
XTAL2
External Oscillator Output
19
XTAL1
External Oscillator Input
20
GND
Ground pin of MCU
21
P2.0(A8)
0th GPIO pin of PORT 2
22
P2.1 (A9)
1st GPIO pin of PORT 2
23
P2.2 (A10)
2nd GPIO pin of PORT 2
24
P2.3 (A11)
3rd GPIO pin of PORT 2
25
P2.4 (A12)
4th GPIO pin of PORT 2
26
P2.5 (A13)
5th GPIO pin of PORT 2
27
P2.6 (A14)
6th GPIO pin of PORT 2
28
P2.7 (A15)
7th GPIO pin of PORT 2
29
PSEN’
Program store Enable used to read external program memory
30
ALE / PROG’
Address Latch Enable / Program Pulse Input
31
EA’ / VPP
External Access Enable / Programming enable Voltage
32
P0.7 (AD7)
Address / Data pin 7 or 7th GPIO pin of PORT 0
33
P0.6 (AD6)
Address / Data pin 6 or 6th GPIO pin of PORT 0
34
P0.5 (AD5)
Address / Data pin 5 or 5th GPIO pin of PORT 0
35
P0.4 (AD4)
Address / Data pin 4 or 4th GPIO pin of PORT 0
36
P0.3 (AD3)
Address / Data pin 3 or 3rd GPIO pin of PORT 0
37
P0.2 (AD2)
Address / Data pin 2 or 2nd GPIO pin of PORT 0
38
P0.1 (AD1)
Address / Data pin 1 or 1st GPIO pin of PORT 0
39
P0.0 (AD0)
Address / Data pin 0 or 0th GPIO pin of PORT 0
40
VCC
Positive pin of MCU (+5V)
Datasheet:
Datasheet of the AT89C52 Microcontroller
Other Atmel 8-bit MCU’s
AT89C51, Atmega328P
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