Identifying duty exemptions via HS code

List of the table of contents of this article:

• 1,Identifying duty exemptions via HS code What is the principle of the control system of the warehouse gate?
• 2, How to understand the schematic diagram and simulation diagram of the single-chip microcomputer?
• 3, 51 Single-chip microcomputer minimum system schematic diagram

What is the principle of the control system of the warehouse gate?

The principle of automatic door is to detect people or vehicles at the door through sensors or infrared sensors, so as to control the opening and closing of the door. This technology not only improves the efficiency of the door, but also reduces the tediousness and safety hazards of manual operation.

In order to illustrate the working principle, the parts in the original figure are marked as follows.

Conversely, when the door switch is closed, the motor drives the winch to close the door, so as to realize the automatic control of the long-distance opening and closing of the gate. The system block diagram is shown in the figure below.

Introduction to the principle of access control system To understand the principle of access control system, you must first know the hardware composition of the access control system. Access control system hardware includes: multi-function scanner, host, controller, motor, transmission device, sensor, each of which has its own important role.

What is the principle of intelligent warehousing management system? Intelligent warehousing is a concept that has emerged in recent years. The goods in the warehouse are complicated and the entry and exit are frequent, which is a great test of the management level.

How to understand the schematic diagram and simulation diagram of the single-chip microcomputer?

General experimental boards can start from the minimum system. It mainly includes the following units: power supply circuit crystal circuit reset circuit programming interface, the current single-chip microcomputer should be the on-board download port, ISP, JTAG, and the interface types are probably serial port, parallel port USB, etc.

This is a single-chip experimental circuit board, with the principle on the left and the wiring on the right.These J symbols are for the convenience of external wiring. For example, J2, the 8-pin plug-in is connected to the P1 port of the single-chip microcomputer on the board, and others are similar. This is to expand the circuit. As for what needs to be connected, just connect according to the schematic diagram.

When the pin of the P0 port writes 1 for the first time, it is defined as a high-impedance input. P0 can be used for external program data memory, and it can be defined as a low octaf of data/address. In FIASH programming, the P0 port is used as the original code input port. When FIASH is verified, P0 outputs the original code. At this time, the external P0 must be connected to the pull-up resistor.

The fourth one is just a string of filter capacitors on the power supply. The actual position may be close to a chip for each capacitor when making the pcb diagram. The fifth one is the connection method of the MAX232 chip.It is an interface chip that converts the signal level of the single-chip microcomputer into the usual COM port, that is, the RS232 interface, which has been eliminated for a long time.

The two "black blocks" are the digital tube. That row of resistors is the pull-up resistor of the P0 port. Of course, it seems to be useless in this circuit... The reset system is actually a simple circuit composed of a resistor, a capacitor and a switch, but it is very important for single-chip microcomputers and cannot be omitted.

51 single-chip microcomputer minimum system schematic

The following figure is the minimum system schematic diagram, that is, with these four parts, the single-chip microcomputer can run. In the first part, the power supply group is usually said to be extremely "ground", and the GND above is the abbreviation of ground in English.In the second part, the crystal vibration group filters out the high-frequency signal of the crystal vibration part to make the crystal vibration more stable when working.

Turn left | Turn right Note: In the figure above, /EA (31 pins) can also be directly connected to the power supply VCC, and the 2k resistance can be removed. 51 Single-chip microcomputer minimum system: clock circuit 51 Clock pin on single-chip microcomputer: XTAL1 (19 pins): chip internal oscillation circuit input.

The smallest system of a single-chip microcomputer is composed of some components necessary to make up a single-chip microcomputer system. In addition to the single-chip microcomputer, it also needs to include a power supply circuit, a clock circuit and a reset circuit. The minimum system circuit of the single-chip microcomputer (the power supply and ground of the single-chip microcomputer are not marked) is shown in Figure 2-7.

Single-chip microcomputer minimum system schematic diagram: 51 single-chip microcomputer minimum systemIntroduction to the unified circuit: The size of the polar capacitance C1 of the minimum system reset circuit of 51 single-chip microcomputer directly affects the reset time of the single-chip microcomputer. Generally, 10~30uF is adopted. The larger the minimum system capacity of 51 single-chip microcomputer, the shorter the reset time required.

If you want to know more, it is recommended to use the single-chip microcomputer experimental board. You can refer to Wu Jianying's 51 single-chip microcomputer experimental board, which is not bad. Question 8: 51 single-chip microcomputer minimum system schematic diagram. Such a simple diagram, Baidu, and there are a lot of them. If you are too lazy to even have such a simple diagram, then I suggest you Don't learn single-chip microcomputers.