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Wiegand

Intruduction​

Wiegand protocol is a communication protocol developed by Motorola, which is applicable to many aspects of card readers and cards related to access control system; the protocol does not define the baud rate of communication and data length. It mainly defines the data transmission mode: Data0 and data1 are used to transmit 0 and 1 respectively. They are mostly used for 26bit, 34bit, 36bit, 44bit, etc.

_images/RS485_en.png

_images/D0_D1.jpg

Debugging​

The RS485 port of Face-RK3399 can be reused as the sending port of Wiegand protocol for data transmission.

DTS configuration​

The Wiegand node is defined in kernel/arch/arm64/boot/dts/rockchip/rk3399-firefly-face.dtsi:

wiegand-gpio {
    compatible = "firefly,wiegandout";
    level_effect = <1>;/*0-low effect 1-high effect*/
    gpio_d0 = <&gpio1 9 GPIO_ACTIVE_HIGH>;
    gpio_d1 = <&gpio1 10 GPIO_ACTIVE_HIGH>;
    gpio_mode_switch = <&gpio1 17 GPIO_ACTIVE_HIGH>;
    status = "okay";

Run commands in device as follow:

echo 0 > /sys/devices/platform/wiegand-gpio/mode_switch  #Switch to Wiegand interface function
echo [card number] > /sys/devices/platform/wiegand-gpio/wiegand26 # Sending Wiegand 26 date
echo [card number] > /sys/devices/platform/wiegand-gpio/wiegand34 # sending Wiegand 34 function

The following is the specific wiring method of Wigan transmission interface. Note that VCC and GND need to be provided through USB.

_images/module_wiegand1_en.png

Wiegand interface can also as GPIO:

# Pull up D0
echo 1 > /sys/devices/platform/wiegand-gpio/D0
# Pull up D1
echo 1 > /sys/devices/platform/wiegand-gpio/D1

The following is the connection diagram of control relay with D0, D1, IO port. Note that VCC and GND need to be provided through USB.

_images/module_D0_D1.png

V2 Wiegand and relay​

In Face-RK3399 V2, the Wiegand interface is updated while it using expansion board. You can lookup by interface definition

NOTE：GND connectting is needed

V2 Wiegand output​

Run commands in device as follow:

echo card number > /sys/devices/platform/wiegand-gpio/wiegand26 # Sending Wiegand 26 date
echo card number > /sys/devices/platform/wiegand-gpio/wiegand34 # sending Wiegand 34 function

V2 Wiegand input​

File system create the node /dev/wiegand.

The following example of Wigand input program:

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <asm-generic/ioctl.h>

#define WG_IOC_MAGIC 'k'

#define WG_IOCGETFUN    _IOR(WG_IOC_MAGIC, 1, int)
#define WG_IOC_FUN_IN   _IOR(WG_IOC_MAGIC, 2, int)  //Set to normal input IO
#define WG_IOC_FUN_WG   _IOR(WG_IOC_MAGIC, 3, int)  //Set ti Wiegand input IO
#define WG_IOCGETD0     _IOR(WG_IOC_MAGIC, 4, int)  //Get IO level
#define WG_IOCGETD1     _IOR(WG_IOC_MAGIC, 5, int)
#define WG_IOCGETWG     _IOR(WG_IOC_MAGIC, 6, int)  //Get Wiegand data

int main()
&#123;
    int fd = 0;
    char dst[12] = &#123; 0&#125;;
    int val;
    int result =0;
    fd = open("/dev/wiegand", O_RDWR);
    if(fd < 0)
    &#123;
        printf("file open error ! \n");
        return -1;
    &#125;
    while(1)
    &#123;
        //result=read(fd, dst, sizeof(dst));
        ioctl(fd, WG_IOC_FUN_WG, &val);
        result = ioctl(fd, WG_IOCGETWG, &val);
        if(result < 0) &#123;
            printf("Unable to get value: %s\n", strerror(errno));
            close(fd);
            return -1;
        &#125; else
            printf("val is %d, size=%d\n", val,result);
        sleep(1);
    &#125;
    /*close the device*/
    close(fd);

    return 0;
&#125;

The above program can receive and print the input data of Wiegand.

V2 relay​

The relay of V2 can control two lines ON/OFF refer to interface definition

echo 0 > /sys/devices/platform/wiegand-gpio/mode_switch # COM and ON connect 
echo 1 > /sys/devices/platform/wiegand-gpio/mode_switch # COM and OFF connect