[MCU project training] eight way answering machine

The single-chip project training ——8 Share it with the road responder , If there is any deficiency , Please point out .

【 Experimental picture 】 

【 Experiment video 】

【 project training 】8 Road responder

Catalog

One 、 The design requirements

Two 、 Options

3、 ... and 、 Hardware circuit design

5、 ... and 、 Other pictures

6、 ... and 、 The data link

7、 ... and 、 About author

8、 ... and 、 Postscript

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One 、 The design requirements

        Design a total 8 Contestants participated 8 Road responder . Each contestant has a scrambler button , For participants . The circuit has the identification and storage functions of the first response signal . After the host sends out the rush to answer instructions , If the contestant presses the answer button at the first time , Then the nixie tube immediately displays the corresponding contestant number , At the same time, the circuit should have self-locking function , Make other contestants' answer keys ineffective .

        Functions and requirements ： Each contestant has an answer button , The number of the button corresponds to the number of the contestant , The responder has the functions of signal identification and data storage and display . If there is a contestant rushing to answer after the rush to answer , The corresponding number is displayed on the nixie tube , At the same time, the circuit should have self-locking function , No other contestants are allowed to rush to answer , Give priority to the number of the contestant , Keep it until the background administrator clears the system , The answering machine has the function of timely answering , After the host sends out the command of rushing to answer, the timer will reduce the time immediately , And display on the display , At the same time, the buzzer makes a short sound . The contestants will rush to answer within the set time , Answer effectively . The timer stops working , The display shows the contestant number , And keep it until the background administrator clears the system .

Two 、 Options

        programme 1： Use hardware electronic components to realize , But the circuit structure is complicated , Debugging difficulty , There are many peripheral components involved , Inconvenient to install , Experiments bring great trouble to experimental operation .

        programme 2： use STC89C52RC Single chip microcomputer , It has 8KB  Flash ROM、512KB  RAM, The instruction code is completely compatible with the traditional 8051, No need for a dedicated simulator , User program can be downloaded directly through serial port , The program download can be completed in a few seconds .STC89C52RC It contains almost all the unit modules required for data acquisition and control , Its internal structure block diagram is as follows ：

          Analyze the above two schemes , From scheme 1 It can be seen that , This answering machine has a answering circuit 、 Timing circuit 、 Alarm circuit 、 Timing control circuit 4 Composed of circuits . The expansion circuit is a second pulse signal generation circuit 、 Decoding circuit 、 Display circuit, etc , It has a full range of functions , The designed circuit is also very stable . But its cost is very high , It uses only eight integrated circuits , Therefore, the single-chip microcomputer scheme is selected .

        The block diagram of the implementation scheme of the eight way responder is shown in the figure ：

3、 ... and 、 Hardware circuit design

        The schematic diagram of the system hardware circuit is shown in the figure below . It mainly includes system administrator buttons （ Reset button ）、3 Host buttons （K1、K2、K3）、8 Players press buttons （S1、S2、S3、S4、S5、S6、S7、S8、S9）、4 Bit common anode nixie tube display circuit 、 Buzzer alarm circuit , And power interface and power indicator circuit .

Four 、 software design

The main function is as follows ：

void main(void)
{   
    timer0_init();
    while(1)
    {
        time_set();
        display_time(time);
        if(user_flag)// When a user key is pressed (user_flag Modified in external interrupt function )
        {
            if(user != ERROR)// When the user key is pressed normally 
                display_user(user);// Displays the number of the user 
            else// If an error is displayed ( When multiple keys are pressed at the same time )
                display_error();// Display error 
        }
            
        if(stop_flag)// When the countdown stops (stop_flag In the timer zero interrupt function equipment modification ), Still no user pressed the button 
            display_error();// Display error 

    }
}

5、 ... and 、 Other pictures

（1）PCB-3D picture

（2） Physical pictures

6、 ... and 、 The data link

（1） Demo video link ：

link ①： Bili, Bili -------- Click play

link ②：

link ③： Iqiyi -------- Click play

link ④： Tencent video -------- Click play

link ⑤： Kwai Kong Videos -------- Click play

（2） Schematic diagram download ：

link ： Baidu SkyDrive -------- Click to download

（3） Source program download ：

link ： Baidu SkyDrive -------- Click to download

7、 ... and 、 Design points

（1） How to integrate 8 User answer keys ,“ comprehensive ” To external interrupt 0 port , Once the user's answer key is pressed , Then the corresponding action will take place immediately through the interrupt response ？

Make full use of the unidirectional conductivity of the diode , Once a key is pressed , Then the external interrupt 0 The port is pulled down , There will be a transition from high level to low level , At this time, enter the external interrupt 0 Respond to , Then by reading the status of the user port , You can achieve the desired effect . Here are diodes “ And ” door , General “ And ” Gate chip , such as 74LS/HC series , A chip costs at least a few cents , And the volume is relatively large , Diode is used here instead “ And ” Gate chip , No matter in terms of price or volume, it is superior to special chips .（ Be careful ： The pull-up resistor here is essential ）

8、 ... and 、 About author

Micro invasive electronic studio , Assassin ari

Nine 、 Postscript

（ Constantly improving ）