The microcontroller at89s52 is a high-performance, low-power 8-bit microcontroller manufactured using CMOS technology. It provides the following standard features: 8K bytes of program memory, 256 bytes of RAM, 32 I/O lines, and 2 16-bit timer/counter, a 5-interrupt source with two priority interrupt structures, a duplex serial port, on-chip oscillator, and clock circuitry. This article first introduced the advantages and disadvantages of the single-chip at89s52 and other microcontrollers, followed by a description of the pin diagram and pin description of the microcontroller at89s52, and finally introduced the main features of the microcontroller at89s52, follow the specific Xiaobian together to understand the next.
advantage:
1, the function than the standard 51 strong so little, more 128BRAM, one more timer, more 512BEEPROM, built-in 8KROM enough to accommodate the general program;
2, easy to buy;
3, a large number of data, programming and 51 compatible, the most suitable for students or beginners to use;
4, support ISP download, use is very convenient;
5, FLASHROM can be downloaded more than 10,000 times;
6, good reliability.
Disadvantages:
1, low performance, and now the new 51 MCU is stronger than the AT89S52 is not one or two, N and more.
2, price is not high, this feature, the price of 6-8 block is not cheap, STC microcontroller function, the price is only half of it;
3, the package is DIP40, too big, is not conducive to industrial production.
MCU at89s52 IntroductionThe AT89S52 is a low power, high performance CMOS 8-bit microcontroller with 8K of in-system programmable Flash memory. Built using Atmel's high-density non-volatile memory technology, it is fully compatible with industrial 80C51 product instructions and pins. On-chip Flash allows program memory to be programmed in the system and is also suitable for conventional programmers. On a single chip, with a clever 8-bit CPU and programmable Flash in the system, AT89S52 provides a highly flexible, ultra-efficient solution for many embedded control applications.
Microcontroller at89s52 pin diagram and description
VCC : Power GND: Ground
P0 port: P0 port is an 8-bit open-drain bidirectional I/O port. As an output port, each bit can drive 8 TTL logic levels. When writing “1†to port P0, the pin is used as a high-impedance input. When accessing external programs and data memory, port P0 is also multiplexed as lower 8-bit address/data. In this mode, P0 has an internal pull-up resistor.
In flash programming, port P0 is also used to receive instruction bytes; during program verification, the instruction byte is output. External pull-up resistors are required for program verification.
Port P1: Port 1 is an 8-bit bidirectional I/O port with an internal pull-up resistor. The p1 output buffer can drive 4 TTL logic levels. When “1†is written to port P1, the internal pull-up resistor pulls the port high and can be used as an input port. When used as an input, pins that are pulled low externally will output current (IIL) due to internal resistance. In addition, P1.0 and P1.2 are used as the external count input (P1.0/T2) of timer/counter 2 and the trigger input (P1.1/T2EX) of timer/counter 2, as shown in the following table.
In flash programming and verification, the P1 port receives the lower 8-bit address byte.
Port P2: Port 2 is an 8-bit bidirectional I/O port with an internal pull-up resistor. The P2 output buffer can drive 4 TTL logic levels. When “1†is written to P2 port, the internal pull-up resistor pulls the port high and can be used as an input port. When used as an input, pins that are pulled low externally will output current (IIL) due to internal resistance. When accessing an external program memory or reading an external data memory with a 16-bit address (for example, MOVX @DPTR), port P2 sends a high eight-bit address. In this application, the P2 port uses a strong internal pull-up to send 1. When using an 8-bit address (such as MOVX @RI) to access external data memory, Port 2 outputs the contents of the P2 latch.
During flash programming and verification, port P2 also receives the upper 8-bit address byte and some control signals.
Port 3: Port 3 is an 8-bit bidirectional I/O port with an internal pull-up resistor. The p2 output buffer can drive up to 4 TTL logic levels. When “1†is written to port P3, the internal pull-up resistor pulls the port high and can be used as an input port. When used as an input, pins that are pulled low externally will output current (IIL) due to internal resistance. The P3 port is also used as a special function (second function) of the AT89S52, as shown in the following table.
In flash programming and verification, P3 also receives some control signals.
RST: Reset input. When the crystal oscillator is running, the RST pin is high for 2 machine cycles to reset the microcontroller. After the watchdog timer is completed, the RST pin outputs a high level of 96 crystal oscillator cycles. The DISRTO bit on the special register AUXR (address 8EH) can disable this function. DISRTO default reset active high.
ALE/PROG: The address latch control signal (ALE) is an output pulse that latches the lower 8-bit address when accessing external program memory.
In flash programming, this pin (PROG) is also used as a programming input pulse.
In general, ALE outputs pulses at a fixed frequency of one sixth of the crystal and can be used as an external timer or clock. However, it is particularly emphasized that the ALE pulse will be skipped each time the external data memory is accessed. If necessary, the ALE operation will be invalid by setting bit 0 of the SFR at address 8EH to "1". This bit is set to "1" and ALE is only valid when executing the MOVX or MOVC instruction. Otherwise, ALE will be pulled up slightly. The setting of this ALE enable flag (bit 0 of the SFR at address 8EH) is invalid for the microcontroller in external execution mode.
PSEN: External program memory strobe signal (PSEN) is an external program memory strobe signal. When the AT89S52 executes external code from external program memory, PSEN is activated twice per machine cycle, while PSEN is not activated when accessing external data memory.
EA/VPP: Access to external program memory control signals. To enable external program memory read instructions from 0000H to FFFFH, the EA must be connected to GND.
In order to execute internal program instructions, the EA should connect VCC. The EA also receives a 12 volt VPP voltage during flash programming.
XTAL1: Input of oscillator inverting amplifier and internal clock generation circuit.
XTAL2: Output of the oscillator inverting amplifier.
1, compatible with MCS-51 microcontroller products;
2, 8K bytes in the system programmable Flash memory;
3, 1000 erase cycles;
4, full static operation: 0Hz-33MHz;
5, three-level encryption program memory;
6, 32 programmable I/O lines;
7, three 16-bit timer / counter;
8, 6 interrupt sources;
9, full-duplex UART serial channel;
10, low-power idle and power-down mode;
11, after the power down interrupt can wake up;
12, watchdog timer;
13, double data pointers;
14, power off identifier.
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