Design of electronic tour guide system based on 51 single chip microcomputer

Introduction

With the improvement of living standards, more and more people regard tourism as a fashionable consumption mode, and some problems have also arisen, such as the lack of tour guides and their low quality, coupled with the emergence of a large number of tourists who like independence and freedom, which has prompted the emergence of electronic tour guide systems. The development of electronic tour guide systems has a process. At the beginning, it was a semi-automatic system. Its function was to store scenic spot information in the form of voice files in the tour guide machine. Generally, the scenic spot code was directly entered through the keyboard and selected to play. The disadvantage of this type of tour guide machine is that it is inconvenient to enter the scenic spot code. Now, fully automated tour guide machines have appeared. It first places wireless transmission modules at the scenic spot. These transmission modules can control the working range, so that there are different coded signals at each scenic spot. After the tourists arrive at the scenic spot, the tour guide in the tourist's hand will automatically receive the coded signal. After decoding, the control center can control the voice playback. This article introduces the design of this fully automated tour guide machine, which uses miniC-A101FS and single-chip microcomputer AT89C2051.

1 Introduction of miniC-A101FS and SC2272

1.1 miniC-A101FS

miniC-A100FS is a voice module controlled by serial port, which is easy to use, flexible to expand and has high performance. This module not only provides a variety of serial port commands to control the voice module playback, but also can provide query commands to the host computer. Its features are as follows:

◆Support MPEG1/2/2.5 layer3 MP3 format playback;

◆Support USB2.0, update music via USB interface;

◆Provide serial port control;

◆Support Flash capacity range: 0～1 024 MB;

◆Support SD card.

1.2 SC2272

SC2272 and SC2262 are used together. They are manufactured using CMOS technology and have up to 12 address pins, which can support up to 531 441 address codes, thus greatly reducing code conflicts. SC2262 completes the transmission and sends out the current address code and data bit data of SC2262. When the addresses of SC2272 and SC2262 are consistent, SC2272 receives more than 2 frames of serial code from SC2262, and the oscillation frequencies of SC2272 and SC2262 must be consistent. When SC2272 receives a valid signal, its pin VT will become high.

2 Circuit and system composition of electronic tour guide system

In the designed system, the RF transmission modules are distributed in various scenic spots in the scenic area, and they work on different addressing signals. The electronic tour guide uses the more common 51 series single-chip microcomputer AT89C2051 as the control processing unit of the system, and uses the P1 port to send 00H~FFH data to the decoding chip SC2272 as their address; at the same time, the RF receiving head J04P sends the received signal to SC2272 for decoding. If the decoded signal is consistent with the signal preset by the single-chip microcomputer to the address, it will trigger the interrupt INT1 and enter the interrupt processing subroutine. In the interrupt processing subroutine, it will enter the corresponding interrupt processing program for playback. TXD will be used for serial communication with the voice module, and INT1 of the P3 port is used for interruption. The system function consists of the transmitting part and the receiving part.

The transmitting part uses a transmitting module that integrates SC2262 and F05P transmitting heads. The working distance can be adjusted by the length of the antenna and the level of the working voltage. The receiving part is the electronic tour guide machine held by tourists. The system block diagram is shown in Figure 1.

When the address code decoded by SC2272 is consistent with the preset address code, the VT pin jumps from low level to high level, and after sending this signal to the inverter for inversion, the interrupt INT1 is triggered; the interrupt control subroutine sends the instruction "2404010000" to the voice playback module through RXD and TXD, and the voice playback module starts to play the scenic spot introduction. The system circuit is shown in Figure 2.

There are 3 buttons in Figure 2, 2 of which are volume buttons and the other one is a reset button. The volume buttons use the principle of "sampling voltages at different points" and are the button circuits that come with the voice playback module; while the reset button uses a classic circuit, where the reset of the microcontroller and the reset of the voice playback module are connected together and work together.

In order to enhance the anti-interference effect, J04P should be perpendicular to the circuit board and should be at a certain distance from the voice playback module on the board diagram, so as to achieve the best anti-interference effect. The oscillator resistors of SC2262 and SC2272 are 1 MΩ and 200 kΩ as the best.

The system also needs to consider whether to repeat the recording after playing it. The function of this design is not to repeat the playback after playing it, unless the visitor presses the reset button, which is achieved through software. In the ROM of the single-chip microcomputer, a 1-byte space is reserved for each scenic spot as its play flag. Whenever entering the scenic spot to play, it is determined whether the flag is 1. If it is, it means that it has been played and will not be played again; otherwise, the scenic spot introduction is played. It can be played repeatedly after pressing reset.

The software flow of the system is shown in Figure 3.

3 Field Testing

In order to verify the reliability of the electronic tour guide equipment, some field tests were carried out and the results were good: ① The distance of the transmitting module is adjustable, which meets the needs of displaying various tourist attractions. Basically, the ideal distance can be obtained by controlling the length of the antenna and the voltage; ② The possibility of bit error is extremely low; ③ Through program control, it is well realized to automatically determine whether to play the same attraction again after it has been played.

Conclusion

The current electronic tour guide system on the market has the following defects: high cost, large size, and small voice storage capacity. The tour guide system introduced in this article uses the wireless RF transmitter/receiver head F05P/J04P and the codec chip SC22262/SC2272, and uses the low-power microcontroller AT89C2051 to control the operation of the voice module, successfully reducing the size (about the size of an ordinary mobile phone). The use of ordinary components on the market has greatly reduced costs. The voice module miniC-A101FS supports a Flash capacity of 0 to 1024MB and supports SD cards, which fundamentally solves the problem of the capacity of the tour guide machine. The device has been put into testing at tourist attractions and has received good feedback. It will soon be put on the market and I believe it will bring good economic and social benefits.