Application of ISD4004 voice chip in voice station announcer

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Application of ISD4004 voice chip in voice station announcer [Copy link]

Abstract: ISD4004 voice chip series is a product launched by ISD Company of the United States. It has the characteristics of multiple recording and playback, long storage time, no need to expand the memory when in use, and simple peripheral circuits. This paper introduces a practical application of ISD4004 chip in voice station announcer, and explains its functions and usage, so that readers can have a preliminary understanding of the use of ISD4004 series voice chip.

Keywords: ISD4004 single chip computer voice station announcer

The ISD4004 voice chip is a new product launched by the American ISD company. The pin description and internal circuit of the voice chip can be easily found in the chip data provided by ISD company. I will not describe it in detail, but simply introduce its features.

Compared with ordinary recording/playback chips, ISD4004 has the following characteristics: first, there is no limit on the segment length of recorded sound, and sound recording does not require A/D conversion and compression; second, using fast flash memory as the storage medium, data can be saved for up to 100 years without power supply, and repeated recording can be performed more than 10,000 times; in addition, ISD4004 has the advantage of long recording time (up to 16 minutes, and the 8-minute ISD4004 voice chip used in this article); finally, the development and application of ISD4004 has the advantage of simple peripheral circuits, which can be seen from its actual application in the voice station announcer introduced in this article.

1. Hardware circuit design of voice station announcer

Most of the voice station announcers currently on the market do not use the ISD4004 series chips, which is related to the fact that they were launched not long ago and the price is relatively high. However, with the increasing application of ISD4004 and the price drop, coupled with the advantages of the ISD4004 series chips themselves, it is believed that it is completely feasible to use the ISD4004 series voice chips in the voice station announcer. The author designed the hardware circuit of the device and conducted on-board debugging, achieving relatively satisfactory results. The voice station announcer discussed in this article mainly refers to the playback circuit installed on the car, and does not include the recording circuit. In actual applications, the recording circuit completes the recording work of the station announcement content and stores the recorded content in the voice chip. This article mainly introduces the typical application of ISD4004 in combination with the use of ISD4004 in the playback circuit.

The main circuit of the station announcer discussed in this paper is mainly composed of single-chip microcomputer 89C52 and ISD4004. The hardware circuit connection diagram of the system is shown in Figure 1.

This system is mainly divided into three parts: single-chip control part, playback part and display part. The display circuit uses two 7-segment digital tube static displays controlled by P3.0 and P3.1, which will not be introduced in detail here; the control part is mainly composed of single-chip 89C52, including necessary key circuits, reset circuits, watchdog circuits and other peripheral circuits; the playback part is mainly composed of ISD4004, including matching transformer circuits, power amplifier circuits, etc.

As can be seen from Figure 1, there are few connections between 89C52 and IS4004. The P1.0~P1.3 pins of the single-chip microcomputer are connected to the buttons to control whether the station announcer plays and the content of the playback during operation; P1.6 is connected to the chip select pin /SS of IS4004 to control whether IS4004 is enabled; P1.7 is connected to the serial input pin MOSI of IS4004, from which the address of the playback is read; P3.0 and P3.1 control the peripheral display circuit to display the current station number during the operation of the station announcer; P3.2 and P3.3 are connected to the serial clock pin SCLK and interrupt pin /INT of IS4004 respectively. The connection required by the IS4004 chip also includes the audio signal output pin AUDOUT, which is connected to the speaker through a filter capacitor; AMCAP is the automatic mute terminal, which is grounded through a capacitor when in use. In addition, since the operating voltage of ISD4004 is 3V, and the power supply voltage required by the microcontroller is 5V, a voltage conversion circuit is required to obtain a 3V voltage for use by ISD4004.

2 Software Design

The program flow chart is shown in Figure 2.

After the circuit is powered on, the program is initialized first, and then the button status is queried to enter the system standby state. If a button is pressed, the program pointed to by the button is executed. The buttons include the play button, stop button, plus one button, minus one button and special language button. In the standby state, if the play button is pressed for the first time, the program will first determine whether it is going or returning (the bus route is generally both going and returning), and light up the corresponding indicator light, automatically read out the playback content of the first station, and the station number is displayed as 1. If it is not pressed for the first time, the current station number is first determined, and the first address of the playback content of the station is obtained based on the station number; then the playback subroutine is called, the first address of the playback content of this station obtained previously is read in, and the playback starts. After each sentence is played, the interrupt pin (pin 25) of ISD4004 will automatically send a low-level signal. In the hardware design, this pin is connected to P3.3 of the microcontroller, so it will cause an interrupt. In the interrupt subroutine, there is a counter to record the number of interrupts, so as to determine when the current station ends, the station number is increased by one and the display is refreshed. After the plus key is pressed, the program will play the next station; after the minus key is pressed, the program will play the previous station, and the corresponding station number display will be refreshed; after the special language key is pressed, the program will play the special language (such as "Please pay attention to the turn"); the stop key will stop the current playback state. In order to facilitate readers' understanding of the application of ISD4004, this article provides some programs.

This part of the program mainly completes the playback operation, sends the address of the playback content obtained to ISD4004, and completes the playback.

PLAY?

ACALL POWERUP ?Online electronic program

ACALL DELAAY 25 ? Delay subroutine, at least

Delay 25ms

CLR P1.6 ?Select ISD4004

MOV PLAY 2?＃１１１０００００B ?Store SETPLAY command

MOV A?PLAY0?Send and play the sound address lower 8 bits

ACALL SEND ?Call the send address subroutine

MOV A?PLAY1?Send and play the sound address high 8 bits

ACALL SYND

MOV A?PLAY２?Send SETPLAY command

ACALL SYND

SETPB 1.6

CLR P1.6

MOV PLAY ING?＃１１１１００００B ?Input the play command

ＭＯＶ A?ＰＬＡＹＩＮＧ

ACALL SYND

SETPB 1.6

RET

POWERUP? Send power-on command subroutine

MOV POWING?＃００１００００Ｂ ?Send power-on signal to voice chip

ＭＯＶ A?ＰＯＷＵＰＩＮＧ

CLR P1.6

ACALL SYND

SETPB 1.6

RET

SEN D: Send instructions to ISD4004.

Subroutines for address, etc.

CLR MOS

CLR P3.2

MOV R1?＃８

OUTBIT1?

CLR P3.2 ?Clock falling

RRC A

MOV MOSIC ? Output 1 bit

NOP

NOP

SETPB P3.2 ?Clock rising edge to

NOP

NOP

NOP

DJNZ R1?OUTBIT1

RET

In the playback program, the programming must be strictly in accordance with the requirements of ISD4004. First, the power-on command must be sent, then wait for a 25 μs delay, then send the 16-bit playback start address, and finally send the 8-bit start playback command.

During the debugging of the playback circuit, first measure whether the working voltage of ISD4004 is 3V. If it is, enter the next level debugging. Then see whether the playback address can be sent in. For this, you can measure the voltage of the AUDOUT pin. If it is 1.2V, it means that the playback address can be read in. Then measure whether it can play sound. You can measure the voltage of the AUDOUT pin. If it is 1.2V, it means that the ISD4004 chip works normally and can play sound. If you can't hear the sound, debug the next-stage playback circuit to see if there is a problem with the next-stage circuit.

The station announcer circuit introduced in this article has been tested and debugged on board and can work stably and reliably.