Combining 51 code code parsing rfid card reader programming ideas

I have been busy with this RFID module in the past two days. First of all, I admit that I am a novice. The platform is based on the 51 single-chip microcomputer for beginners, but I still summarize what I have gained from reading the code in the past two days.

Software design of the card reader: It seems that the PDF document has been given, but it takes a long time for beginners to understand it. Here I show the design process in the datasheet, and combine it with code analysis to achieve the effect of identifying the card.

First of all, it seems to be a reset response. According to the description in the datasheet, the communication protocol and baud rate of the MIFARE radio frequency card are defined. When a card enters the operating range of the card reader, the card reader will communicate with it using a specific protocol to determine whether the card entering is a MIFARE radio frequency card.

In fact, this paragraph on the datasheet seems to be very impressive, but in fact it gives people a feeling of being confused. In fact, after reading the code, I know that Liu Chen on the software is called initialization. It is necessary to perform a software reset on the card reader and set the working mode of the card reader.

Here the code is:

 PcdReset(); //rc522 initialization

 PcdAntennaOff(); //Turn off the antenna

 PcdAntennaOn(); //Turn on the antenna

 M500PcdConfigISOType('A'); //Set working mode

 The second step is anti-collision. The datasheet says: When multiple cards enter the sensing range of the card reader, the anti-collision mechanism will be activated and automatically operate from multiple cards. After that, there seems to be a lot of words about how to prevent collision.

In fact, I personally feel that the code is more important, because without reading the card, where does the anti-collision come from? In fact, after talking so much about anti-collision, it is just a function to implement it.

 status = PcdRequest(PICC_REQALL, g_ucTempbuf);

        //PICC_REQALL is a macro definition which means to find all cards in the antenna.

        // g_ucTempbuf is an array. Here the function reads the first two digits in the card and puts them in the array.

   status = PcdAnticoll(g_ucTempbuf); // Anti-collision

What's interesting here is that sometimes you need to determine the type of card. Here is a snippet that should be used in the program.

Determine the type of card and the first bit of data returned when reading the card. Other functions use 12864, so you don't need to go into details here.

                 //If there is a card, determine what card it is and then display it on the LCD

                    // 0x4400 = Mifare_UltraLight

                    // 0x0400 = Mifare_One(S50)

                    // 0x0200 = Mifare_One(S70)

                    // 0x0800 = Mifare_Pro(X)

                    // 0x4403 = Mifare_DESFire

                 switch(g_ucTempbuf[0])

                 {

                     case 0x44:

                             ck12864_com(0x93);

                            for(i=0;i<10;i++)

                            {

                                    ck12864_data(leixing1[i]);

                            }

                         break;

                     case 0x02:

                          ck12864_com(0x93);

                             for(i=0;i<8;i++)

                            {

                                    ck12864_data(leixing2[i]);

                            }

                         break;

                     case 0x04:

                          ck12864_com(0x93);

                            for(i=0;i<8;i++)

                            {

                                    ck12864_data(leixing3[i]);

                            }

                         break;

                     case 0x08:

                          ck12864_com(0x93);

                             for(i=0;i<6;i++)

                            {

                                    ck12864_data(leixing4[i]);

                            }

                         break;

                 }

The next step is process 3, where you select a card, operate on it, and get the serial number of the selected card according to the datasheet, and return the card capacity at the same time:

Code:

 status = PcdSelect(g_ucTempbuf);

Process 4, that is, to operate the selected card, first verify the password, which includes read and write operations

The implementation of the code is also two sentences:

  status = PcdAuthState(PICC_AUTHENT1A, 5, DefaultKey, g_ucTempbuf);

         if (status != MI_OK)

         { continue; }

         //Write data to the block

         status = PcdWrite(5, data1);

         if (status != MI_OK)

         { continue; }

         //Read a piece of data

Step 5: Put the card into sleep mode:

     PcdHalt();

 These 5 steps can realize the specific operation process of the card. Now we control the stepper motor by swiping the card, and we can actually skip step 4.

If you want to open the door without a specific card number, you can now do it.

Sample code:

#include

#include "mian.h"

#include "rc522.h"

typedef unsigned int uint;

typedef unsigned char uchar;

uchar status;

uchar g_ucTempbuf[20];

void main()

{

    uint i;

    //initialization:

    PcdReset(); //rc522 initialization

    PcdAntennaOff(); //Turn the antenna off and on

    PcdAntennaOn();

    M500PcdConfigISOType('A'); //Set working mode

    // Anti-collision, a loop is needed here to let the card reader read the card continuously

    while(1)

    {

        status = PcdRequest(PICC_REQALL, g_ucTempbuf);

        //PICC_REQALL is a macro definition which means to find all cards in the antenna.

        // g_ucTempbuf is an array. Here the function reads the first two digits in the card and puts them in the array.

        if(status != MI_OK) //No card found, continue to execute PcdRequest()

        {

              continue;

        }

        status = PcdAnticoll(g_ucTempbuf); // Anti-collision

        //Card serial number, 4 bytes, the status here can be used to judge the execution status of PcdAnticoll

        //If the execution is successful, it means that the unique card number has been recorded on g_ucTempbuf

        //Here g_ucTempbuf has used 2+4

        if(status != MI_OK) //No card found, continue to execute PcdRequest()

        {

              continue;

        }

        PcdHalt();

        if(status == MI_OK)

        {

          LED_GREEN =0;

          for(i=0;i<125;i++)

             {

                step();

              }

          LED_GREEN = 1;

           }

       }

}

void DelayMs(unsigned int _MS)

{

    TH1 = (unsigned char)(RCAP2_1ms>>8);

    TL1 = (unsigned char)(RCAP2_1ms);

    ET1 = 0; // Disable timer2 interrupt

    TR1 = 1;

    while (_MS--)

    {  

        while (!TF1);

        TF1 = 0;

        TH1 = (unsigned char)(RCAP2_1ms>>8);

        TL1 = (unsigned char)(RCAP2_1ms);

    }

    TR1 = 0;

}

Analyze the code: This code only contains a card search, anti-collision, and confirming that the door can be opened with a card. This is the most primitive door opening routine, just like turning on an LED light. The next work only requires specific operations on the card.