無法使用libusb接收數據

Question

我想要將數據從設備發送到PC，反之亦然。我正在發送字符串，但無法完全接收。實施例：已發送字符串是Hello，並且輸出是：

Received:H 
Error in read! e = -4 and received = 5 

---

#include <string.h> 
    #include<stdio.h> 
    #include <stdlib.h> 
    #include <libusb-1.0/libusb.h> 

    #define BULK_EP_OUT  0x01 
    #define BULK_EP_IN  0x81 

    /*find these values using lsusb -v*/ 

    uint16_t VENDOR = 0x0483; 
    uint16_t PRODUCT = 0x5740; 
    int main(void) 
    { 
     int ret = 1; //int type result 
     struct libusb_device **usb_dev; 
    struct libusb_device_descriptor desc; 
     struct libusb_device_handle *handle = NULL; 
    struct device_handle_expected; 
    //struct libusb_device_handle device_expected_handle = NULL; 
     struct libusb_device *dev, *dev_expected; 
     char *my_string, *my_string1; 
     int e = 0, config; 
     char found = 0; 
     int transferred = 0; 
     int received = 0; 
     int length = 0; 
     int i=0; 
     int count; 

     /*struct libusb_device *dev; 
     struct libusb_device **devs; 
     struct dev_expected;*/ 

     // Initialize libusb 
     ret = libusb_init(NULL); 
     if(ret < 0) 
     { 
      printf("\nFailed to initialise libusb\n"); 
      return 1; 
     } 
     else 
      printf("\nInit successful!\n"); 

     // Get a list of USB devices 
     count = libusb_get_device_list(NULL, &usb_dev); 
     if (count < 0) 
     { 
      printf("\nThere are no USB devices on the bus\n"); 
      return -1; 
     } 
     printf("\nToally we have %d devices\n", count); 

     while ((dev = usb_dev[i++]) != NULL) 
     {  

      ret = libusb_get_device_descriptor(dev, &desc); 
      if (ret < 0) 
       { 
       printf("Failed to get device descriptor\n"); 
       libusb_free_device_list(dev, 1); 
       break; 
      } 

      e = libusb_open(dev, &handle); 
      if (e < 0) 
      { 
       printf("Error opening device\n"); 
       libusb_free_device_list(dev, 1); 
       libusb_close(handle); 
       break; 
      } 

      if(desc.idVendor == 0x0483 && desc.idProduct == 0x5740) 
      { 
       found = 1; 
      break; 
      } 
     }//end of while 
     if(found == 0) 
     { 
      printf("\nDevice NOT found\n"); 
      libusb_free_device_list(usb_dev, 1); 
      libusb_close(handle); 
      return 1; 
     } 
     else 
     { 
      printf("\nDevice found"); 
      // dev_expected = dev; 
      //device_handle_expected = handle; 
     } 

     e = libusb_get_configuration(handle, &config); 
     if(e!=0) 
     { 
      printf("\n***Error in libusb_get_configuration\n"); 
      libusb_free_device_list(usb_dev, 1); 
      libusb_close(handle); 
      return -1; 
     } 
     printf("\nConfigured value: %d", config); 

     if(config != 1) 
     { 
      libusb_set_configuration(handle, 1); 
      if(e!=0) 
      { 
       printf("Error in libusb_set_configuration\n"); 
       libusb_free_device_list(usb_dev, 1); 
       libusb_close(handle); 
       return -1; 
      } 
      else 
       printf("\nDevice is in configured state!"); 
     } 



     if(libusb_kernel_driver_active(handle, 0) == 1) 
     { 
      printf("\nKernel Driver Active"); 
      if(libusb_detach_kernel_driver(handle, 0) == 0) 
       printf("\nKernel Driver Detached!"); 
      else 
      { 
       printf("\nCouldn't detach kernel driver!\n"); 
       libusb_free_device_list(usb_dev, 1); 
       libusb_close(handle); 
       return -1; 
      } 
     } 

     e = libusb_claim_interface(handle, 0); 
     if(e < 0) 
     { 
      printf("\nCannot Claim Interface"); 
      libusb_free_device_list(usb_dev, 1); 
      libusb_close(handle); 
      return -1; 
     } 
     else 
      printf("\nClaimed Interface\n"); 

     int nbytes = 64; 
     my_string = (char *) malloc(nbytes + 1); 
     my_string1 = (char *) malloc(nbytes + 1); 

     memset(my_string, '\0', 64);//The C library function void (an unsigned char) to the first n characters of the string pointed to, by the argument str. 
     memset(my_string1, '\0', 64); 

     strcpy(my_string, "Hello"); 
     length = strlen(my_string); 

     printf("\nTo be sent: %s", my_string); 

     e = libusb_bulk_transfer(handle, BULK_EP_OUT, my_string, length, &transferred, 0); 
     if(e == 0 && transferred == length) 
     { 
      printf("\nWrite successful!"); 
      printf("\nSent %d bytes with string: %s\n", transferred, my_string); 
     } 
     else 
      printf("\nError in write! e = %d and transferred = %d\n", e, transferred); 

     // sleep(3); 
     i = 0; 

     for(i = 0; i <= length; i++) 
     { 
      e = libusb_bulk_transfer(handle, BULK_EP_IN, my_string1,length, &received, 0); //64: Max Packet Length 
      if(e == 0 && received == length) 
      { 
       printf("\nReceived:"); 
       printf("%c", my_string1[i]); 
      sleep(5); 
      } 
      else 
      { 
       printf("\nError in read! e = %d and received = %d bytes\n", e, received); 
       return -1; 
      } 
     } 

     libusb_release_interface(handle, 0); 
    libusb_free_device_list(usb_dev, 1); 

     libusb_close(handle); 
     libusb_exit(NULL); 

     printf("\n"); 
     return 0; 
    } 

Answer 1

漂亮某些散裝在傳輸將一次傳輸整個緩衝區（最多64個 - 或512，如果你做高速 - 字節），而不是一次一個字節。

您正在遍歷預期緩衝區的大小併爲每個字節執行批量操作，並僅打印出第一個字節。

擺脫閱讀上的for循環，並將printf（）更改爲printf（「％s \ n」，my_string1）;