Single Chip Microcomputer pin introduction

The 40 pins of a microcontroller can be divided into 4 categories: power , clock , control , and I/O pins .

1. Power supply:

⑴VCC-Chip power supply, connect to the + +;
⑵vss-ground end;

2. Clock:

XTAL1, XTAL2-crystal oscillator circuit inverting input and output terminals.

3. Control lines: control lines Total 4,
           ⑴ale/prog: Address latch allow/on-chip EPROM programming pulse
                   ①ale function: Used to latch a low 8-bit address sent by P0 Port
&N Bsp                  ②prog features: A chip with an EPROM on the chip, which inputs a programming pulse during EPROM programming.
           ⑵psen: External ROM read-through signal.
           ⑶RST/VPD: RESET/Standby power supply.
                   ①rst (reset) function: Reset signal input.
                   ②VPD function: The standby power supply            ⑷EA/VPP: internal and external ROM selection/on-chip EPROM programming power supply.
                   ①EA features: internal and external rom selector.
                   ②VPP features: A chip with EPROM on the chip, in EPROM programming period , the programmable power supply VPP is applied.

4.I/O Mouth:
The 80C51 has a total of 4 8-bit parallel I/O ports: P0, P1, P2, P3 ports, a total of 32 pins. The P3 port also has a second function for the special signal input and output and the control signal (belongs to the control bus).

Get a piece of chip, want to use it, first must know how to connect, we use a piece called 89c51 chip , below we see how to connect it.

1. Power: This is of course essential. The microcontroller uses a 5V power supply, where the positive connection 40 pins, the negative (ground) to connect 20 pins.
2. Vibration Pinene Circuit: single-chip microcomputer is a sequential circuit, must supply the pulse signal to work normally, the inside of the monolithic integrated circuits has the oscillator , uses the crystal oscillator, after 18, 19 feet. As long as buy crystal oscillator, capacitance, even on the can, according to Figure 1 can be connected.
3. Reset pin: as shown in Figure 1, as to the meaning of the reset and why the need to reset, in the SCM function is introduced.
4. ea PIN:The EA pins are connected to the positive supply side. At this point, a single-chip microcomputer is connected, on-power, the microcontroller began to work.

Single Chip Microcomputer pin introduction