Hacemos una tarjeta de red USB externa de ENC28J60

ENC28J60 es un controlador Ethernet simple que puede actuar como una tarjeta de red externa para computadoras de placa única con GPIO (incluso hay un controlador listo para usar para la frambuesa) y otros arduins. Los GPIO no se muestran en mi computadora portátil, intentemos solucionar este defecto y atornille el ENC28J60 con STM32F103 y un cordón USB.

Veamos cómo puedes hacer esto.

Nosotros necesitamos:

• ENC28J60

  
  
  
  
  

• STM32 USB device (, ):

  
  
  
  
  

• Linux ( Ubuntu 16)

  
  
  
  
  

• Ethernet ( raspberry pi), wi-fi ( )

  
  
  
  
  

STM32F103 , . ENC28J60 ( c ). ENC28J60 STM32F103 SPI1 .

(usb) -> stm32(SPI) -> ENC28J60(Ethernet ) -> raspberry

, user space. tap ( , Ethernet , tun , ip ), ( tap_handler.c). Linux, tap_handler' tap . , , tap , tap_handler', - . , tap_handler tap , /dev/ttyACM0 ( USB Linux). /dev/ttyACM0, tap .

( vpn). , .

STM32 CubeMX USB CDC (virtual com port). SMT32 Linux /dev/ttyACM0 ( ). , STM32, , STM32.

STM32 . ( CDC_Receive_FS



usbd_cdc_if.c) ENC28J60, , ENC28J60 CDC_Transmit_FS



.

, CDC . , . , ( , wireshark usb). , - - STM32, , .. . .

:

sudo openvpn --mktun --dev tap0

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

ip :

sudo ifconfig tap0 10.0.0.1/24 up

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

tap_handler.

/dev/ttyACM0 raw (, .). :

char cdc_name[20]="/dev/ttyACM0";
int tty_fd = open(cdc_name, O_RDWR | O_NOCTTY); 
struct termios portSettings;
tcgetattr(tty_fd, &portSettings);
cfmakeraw(&portSettings);
tcsetattr(tty_fd, TCSANOW, &portSettings);
tcflush(tty_fd, TCOFLUSH);

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

tap_handler tap0:

/*  dev      tap0*/
int tun_alloc(char *dev, int flags) {
    struct ifreq ifr;
    int fd, err;
    char *clonedev = "/dev/net/tun";
    /*     /dev/net/tun */
    if( (fd = open(clonedev , O_RDWR)) < 0 ) {
        perror("Opening /dev/net/tun");
        return fd;
    }    
    memset(&ifr, 0, sizeof(ifr));

    ifr.ifr_flags = flags;
    
    /*    tap0 */
    if (*dev) {
        strncpy(ifr.ifr_name, dev, IFNAMSIZ);
    }
    /*    */
    if( (err = ioctl(fd, TUNSETIFF, (void *)&ifr)) < 0 ) {
        perror("ioctl(TUNSETIFF)");        
        close(fd);
        return err;
    }
    
    strcpy(dev, ifr.ifr_name);

    return fd;
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

main.c :

strcpy(tun_name, "tap0");
int tap_fd = tun_alloc(tun_name, IFF_TAP | IFF_NO_PI);

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

IFF_TAP (tap). IFF_NO_PI , .

tap0 /dev/ttyACM0. , tap_handler select:

while(1) {
    int ret;
    fd_set rd_set;

    FD_ZERO(&rd_set);
    /* tap_fd - tap inteface descriptor */
    FD_SET(tap_fd, &rd_set);
    /* tty_fd - /dev/ttyACM0 descriptor */
    FD_SET(tty_fd, &rd_set);

    ret = select(maxfd + 1, &rd_set, NULL, NULL, NULL);
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. tap0 tap_handler STM32 ( : - 4 , , 2 - , ) /dev/ttyACM0. , :

if(FD_ISSET(tap_fd, &rd_set)) {    
    uint16_t nread = cread(tap_fd, buffer, BUFSIZE);   
    uint8_t buf[6];
    *(uint32_t *)buf = PACKET_START_SIGN;
    *(uint16_t *)(buf + 4) = nread;    
    cwrite(tty_fd,(char *)buf,6);    
    cwrite(tty_fd, buffer, nread);
    delay_micro(delay_m);    
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

/dev/ttyACM0, ( 4 ), , . tap :

if(FD_ISSET(tty_fd, &rd_set)) {
    uint32_t sign;
    /*   */
    int nread = read_n(tty_fd, (char *)&sign, sizeof(sign));
    /*  ,    */
    if(nread == 0) {        
      break;
    }
    /*   ,      4  */
    if(sign != PACKET_START_SIGN){       
      continue;
    }
    /*    */
    nread = read_n(tty_fd, (char *)&plength, 2);
    if(nread == 0) {        
      break;
    }

    if (nread != 2){        
      continue;
    }
  /*   ,        */
    if(flag){
      flag = 0;
      nread = cread(tty_fd, buffer, sizeof(buffer));
      if(nread != 6){        
        continue;
      }
    }
  /*    ,   */
    if(plength > BUFSIZE){      
      break;
    }

    /*   (plength )      tap interface*/
    nread = read_n(tty_fd, buffer, plength);            
    if (nread != 0){            
        cwrite(tap_fd, buffer, nread);            
        delay_micro(delay_m);
    }
  }
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

STM32

USB CDC CubeMX HAL SPI1 .

callback' CDC_Receive_FS



( usbd_cdc_if.c), USB. , , ENC28J60. :

/* USB_POINTERS_ARRAY_SIZE -  array_pos */
/* MAX_FRAMELEN -    */
/* USB_BUFSIZE -    */

extern uint8_t usb_buf[]; /*        */
extern uint32_t pos_int; /*         */
extern uint32_t array_pos[]; /*    ,         */
extern uint32_t p_a; /*     array_pos  CDC_Receive_FS*/
extern uint32_t pl_a;/*     array_pos    */

/* USB_POINTERS_ARRAY_SIZE -  array_pos */
/* MAX_FRAMELEN -    */
/* USB_BUFSIZE -    */

static int8_t CDC_Receive_FS(uint8_t* Buf, uint32_t *Len)
{
  int8_t memok = 1;
  /*   ,        */
  if( pl_a !=0 && p_a !=0){
    int32_t mem_lag = array_pos[(p_a - 1) % USB_POINTERS_ARRAY_SIZE] - array_pos[(pl_a - 1) % USB_POINTERS_ARRAY_SIZE];
    if(mem_lag > USB_BUFSIZE - MAX_FRAMELEN)
      memok = 0;
  }
  /*      ,
         (array_pos) */
  if(*Len < USB_BUFSIZE && *Len != 0 && memok){
    uint16_t offset = pos_int % USB_BUFSIZE;
    uint16_t new_pos = offset + *Len;
    uint8_t split = 0;
    if (new_pos > USB_BUFSIZE){
      split = 1;
    }
    if(split){
      int len1 = USB_BUFSIZE - offset;
      int len2 = *Len - len1;
      memcpy(usb_buf + offset, Buf, len1);
      memcpy(usb_buf, Buf + len1, len2);
    }
    else
      memcpy(usb_buf + offset, Buf, *Len);
    pos_int += *Len;

    array_pos[p_a % USB_POINTERS_ARRAY_SIZE] = pos_int;
    p_a++;
  }
  USBD_CDC_SetRxBuffer(&hUsbDeviceFS, &Buf[0]);
  USBD_CDC_ReceivePacket(&hUsbDeviceFS);
  return (USBD_OK);
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

(main.c) ENC28J60:

if(pl_a < p_a){    
  uint32_t prev = 0;
  if(pl_a > 0)
    prev = array_pos[(pl_a - 1) % USB_POINTERS_ARRAY_SIZE];
  /*   ( ),   CDC_Receive_FS */
  int32_t n = array_pos[pl_a % USB_POINTERS_ARRAY_SIZE] - prev;//usb frame size
  /*      */
  uint8_t *from = usb_buf + prev % USB_BUFSIZE;
  /*    */
  uint8_t right_n = 1;
  if (n < 0 || n > MAX_FRAMELEN){
    right_n = 0;
  }

  /*    .      6  ( 4   2  ) */
  if((packet_len == 0) && packet_start && (n > 5) && right_n){
    /* .       */
    uint32_t sign = read32(from,usb_buf); 
    /*      4  */
    uint8_t *next = next_usb_ptr(from,usb_buf,4);
    /*    */
    packet_size = read16(next,usb_buf);// 2 bytes after sign is packet length
    /*    */
    if (packet_size > MAX_FRAMELEN || sign != PACKET_START_SIGN){      
      packet_size = 0;
    }
    else{
      /*        */
      next = next_usb_ptr(from,usb_buf,6);
      copy_buf(packet_buf, next, usb_buf, n - 6);      
      packet_len = n - 6;
      packet_next_ptr = packet_buf + packet_len;
      packet_start = 0;
    }

  }
  /*      */
  else if(packet_len < packet_size && right_n){
  /*        */    
    copy_buf(packet_next_ptr, from, usb_buf, n);    
    packet_len += n;
    packet_next_ptr = packet_buf + packet_len;
  }
  /*    */
  else if (packet_len > packet_size){    
    packet_len = 0;
    packet_start = 1;
  }
  /*    enc28j60 */
  if(packet_len == packet_size && packet_size > 0){    
    enc28j60_packetSend(packet_buf, packet_size);
    packet_len = 0;
    packet_start = 1;
  }

  pl_a++;
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

ENC28J60 USB :

len = enc28j60_packetReceive(net_buf,sizeof(net_buf));
if (len > 0) {
  *((uint16_t*)(sign_buf + 4)) = len;
  while(CDC_Transmit_FS(sign_buf, sizeof(sign_buf)) == USBD_BUSY_CDC_TRANSMIT);
  while(CDC_Transmit_FS(net_buf, len) == USBD_BUSY_CDC_TRANSMIT);
  HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

CDC_Transmit_FS



, while. CDC_Transmit_FS



USBD_BUSY_CDC_TRANSMIT



USBD_BUSY



. :

if (hcdc->TxState != 0){
    return USBD_BUSY_CDC_TRANSMIT;
}

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

ENC28J60 enc28j60_ini



, (promiscuous mode):

enc28j60_writeRegByte(ERXFCON,0);

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Raspberry

eth0 ip . ping

sudo ifconfig eth0 up 10.0.0.2/24
ping 10.0.0.2

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

tcpdump:

sudo tcpdump -i eth0

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

STM32 , ENC28J60 raspberry. STM32 , arp / icmp ( ping). , /dev/ttyACM0:

ls /dev/ttyACM*

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

tap_handler:

gcc tap_handler.c -o tap_handler
./tap_handler

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

tap_handler - raspberry, tap0, , STM32, raspberry , .

.

raspberry ssh wi-fi , , default gateway. , raspberry :

sudo route del default gateway 192.168.1.1
sudo route add default gateway 10.0.0.2

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

DNS ( /etc/resolv.conf nameserver, , 8.8.8.8).

Raspberry

eth0 wlan0 NAT:

echo 1 | sudo tee -a /proc/sys/net/ipv4/ip_forward
sudo iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. , ( 0.5 /).

No tiene que preocuparse por la frambuesa, pero conecte directamente el cable de red del enrutador al ENC28J60 (debe apagar el wi-fi en su computadora y configurar la dirección tap0 correcta). Pero probar es más fácil con frambuesa, puedes ver todo lo que sucede en tcpdump.

Por qué todo esto

Probablemente no sea muy conveniente usar un paquete de este tipo en la vida real (especialmente si hay adaptadores USB ethernet económicos a la venta), pero fue muy interesante hacerlo. Gracias por la atención. Enlace de código (proyecto en Atollic TrueStudio).