我制作了一个可以使用USB的C程序。但是我有一个错误-1，表示我有一些输入/输出错误。
我的C代码在下面。我将解释它是如何工作的。函数getDevices()打印出vendor ID和product ID以及device name。运行函数getDevices()时，请记住那些。
然后，您必须选择要连接的设备。选择设备后，请在此处vendor ID和product ID中写入。
#define USB_VENDOR_ID 1155
#define USB_PRODUCT_ID 14415 /* USB product ID used by the device */
在那之后，您需要运行功能connectUSB()。它只需连接到您已写入USB_VENDOR_ID和USB_PRODUCT_ID的USB设备上即可。
我在阅读传入消息时遇到问题。尝试阅读时出现错误LIBUSB_ERROR_IO = -1。
那么，当我尝试阅读时为什么会出现-1错误？我尝试过：
如果要尝试使用我的代码，则必须安装LibUSB。在Deb，Ubuntu，Raspberry等基于Deb的系统中，可以通过在终端中编写此命令来完成此操作。
sudo apt-get install libusb-1.0.0-dev libusb-1.0-0
下面的我的C代码。
#include <stdio.h>
#include <stdlib.h>
#include <libusb-1.0/libusb.h>
#include <string.h>
libusb_context *CONTEXT; //a libusb session
libusb_device_handle *DEVICEHANDLE; //a device handle
libusb_device * DEVICE_POINTER; // a pointer to a device
libusb_device **ARRAY_OF_POINTERS_TO_DEVICE; // an array of pointers to devices
ssize_t NUMBER_OF_USB_DEVICES; // Initial zero devices
static uint8_t receiveBuf[64];
uint8_t transferBuf[64];
uint16_t counter = 0;
#define USB_ENDPOINT_IN 0x80 /* endpoint address */
#define USB_ENDPOINT_OUT 0x01 /* endpoint address */
#define USB_TIMEOUT 3000 /* Connection timeout (in ms) */
#define USB_VENDOR_ID 1155
#define USB_PRODUCT_ID 14415 /* USB product ID used by the device */
/*
* Here we are going to read the USB
*/
int readUSB() {
int nread, r, counter = 0;
nread = 4;
int transfered;
unsigned char data[4];
r = libusb_bulk_transfer(DEVICEHANDLE, USB_ENDPOINT_IN, data, nread, &transfered, USB_TIMEOUT);
if (LIBUSB_ERROR_TIMEOUT == r) {
printf("LIBUSB_ERROR_TIMEOUT = %d\n", r);
return -1;
}else if(LIBUSB_ERROR_PIPE == r){
printf("LIBUSB_ERROR_PIPE = %d\n", r);
return -1;
}else if(LIBUSB_ERROR_OVERFLOW == r){
printf("LIBUSB_ERROR_OVERFLOW = %d\n", r);
return -1;
}else if(LIBUSB_ERROR_NO_DEVICE == r){
printf("LIBUSB_ERROR_NO_DEVICE = %d\n", r);
return -1;
}else if(LIBUSB_ERROR_IO == r){
printf("LIBUSB_ERROR_IO = %d\n", r);
return -1;
} else {
printf("r = %d, %d receive %d bytes from device: %s\n", r, ++counter, nread, data);
return 0;
}
return 0;
}
/*
* Here are we going to write to the USB
*/
int writeUSB() {
int n, ret;
uint16_t count = 0;
//count up
n = sprintf(transferBuf, "%d\0", count++);
//write transfer
//probably unsafe to use n twice...
ret = libusb_bulk_transfer(DEVICEHANDLE, USB_ENDPOINT_OUT, transferBuf, n,
&n, USB_TIMEOUT);
//Error handling
switch (ret) {
case 0:
printf("send %d bytes to device\n", n);
return 0;
case LIBUSB_ERROR_TIMEOUT:
printf("ERROR in bulk write: %d Timeout\n", ret);
break;
case LIBUSB_ERROR_PIPE:
printf("ERROR in bulk write: %d Pipe\n", ret);
break;
case LIBUSB_ERROR_OVERFLOW:
printf("ERROR in bulk write: %d Overflow\n", ret);
break;
case LIBUSB_ERROR_NO_DEVICE:
printf("ERROR in bulk write: %d No Device\n", ret);
break;
default:
printf("ERROR in bulk write: %d\n", ret);
break;
}
return -1;
return 0;
}
/*
* This will connect to our USB device
*/
int connectUSB() {
int r;
r = libusb_init(&CONTEXT);
if(r > 0){
printf("Libusb_init error %d\n", r);
return -1;
}
//libusb_set_debug(CONTEXT, 0);
//Open Device with VendorID and ProductID
DEVICEHANDLE = libusb_open_device_with_vid_pid(CONTEXT, USB_VENDOR_ID, USB_PRODUCT_ID);
if (DEVICEHANDLE == NULL) {
perror("DEVICEHANDLE == NULL");
return -1;
}
//Claim Interface 0 from the device
r = libusb_claim_interface(DEVICEHANDLE, 0);
if (r == LIBUSB_ERROR_NOT_FOUND) {
fprintf(stderr, "LIBUSB_ERROR_NOT_FOUND = %d\n", r);
return -1;
}else if(r == LIBUSB_ERROR_BUSY){
fprintf(stderr, "LIBUSB_ERROR_BUSY = %d\n", r);
return -1;
}else if(r == LIBUSB_ERROR_NO_DEVICE){
fprintf(stderr, "LIBUSB_ERROR_NO_DEVICE = %d\n", r);
return -1;
}
printf("Interface claimed\n");
return 0;
}
/*
* This will show all the devices for USB and send it thru sockets
*/
int getDevices() {
/*
* Special local device handle for only get the name of the USB device
*/
libusb_device_handle *DEVICEHANDLE_NULL; //a device handle
/*
* Compute the number of USB
*/
int returnValue = libusb_init(NULL);
NUMBER_OF_USB_DEVICES = libusb_get_device_list(NULL,
&ARRAY_OF_POINTERS_TO_DEVICE);
/*
* Create our list of Vendor, Product and device
* Vendor and product are important for connect the USB and device is important for the user to see which USB to connect
*/
uint16_t vendor[NUMBER_OF_USB_DEVICES];
uint16_t product[NUMBER_OF_USB_DEVICES];
char device[NUMBER_OF_USB_DEVICES][256 * 2];
/*
* Loop thru all USB devices
*/
ssize_t deviceIndex = 0;
while (deviceIndex < NUMBER_OF_USB_DEVICES) {
/*
* Get the description of the USB device
*/
DEVICE_POINTER = ARRAY_OF_POINTERS_TO_DEVICE[deviceIndex];
struct libusb_device_descriptor deviceDescriptor;
returnValue = libusb_get_device_descriptor(DEVICE_POINTER,
&deviceDescriptor);
if (returnValue != LIBUSB_SUCCESS)
break;
/*
* Open the USB device with NULL. It's only because we want the name of the USB device
*/
DEVICEHANDLE_NULL = NULL;
returnValue = libusb_open(DEVICE_POINTER, &DEVICEHANDLE_NULL);
if (returnValue != LIBUSB_SUCCESS) {
/*
* There was an error. Not success.
*/
if (DEVICEHANDLE_NULL != NULL) {
libusb_close(DEVICEHANDLE_NULL);
DEVICEHANDLE_NULL = NULL;
}
/*
* Write as there was no info at all to display
*/
product[deviceIndex] = 0;
vendor[deviceIndex] = 0;
memcpy(device[deviceIndex], "-", 256 * 2 * sizeof(char));
deviceIndex++;
continue;
}
/*
* Get the string associated with iManufacturer index.
*/
const int STRING_LENGTH = 256;
unsigned char stringManufacturer[STRING_LENGTH];
unsigned char stringProduct[STRING_LENGTH];
char stringDeviceName[STRING_LENGTH * 2];
if (DEVICEHANDLE_NULL != NULL && deviceDescriptor.iManufacturer > 0) {
returnValue = libusb_get_string_descriptor_ascii(DEVICEHANDLE_NULL,
deviceDescriptor.iManufacturer, stringManufacturer,
STRING_LENGTH);
if (returnValue < 0)
break;
}
/*
* Get string associated with iProduct index.
*/
if (DEVICEHANDLE_NULL != NULL && deviceDescriptor.iProduct > 0) {
returnValue = libusb_get_string_descriptor_ascii(DEVICEHANDLE_NULL,
deviceDescriptor.iProduct, stringProduct, STRING_LENGTH);
if (returnValue < 0)
break;
}
/*
* Combine manufacturer and product
*/
strcpy(stringDeviceName, (char*) stringManufacturer);
strcat(stringDeviceName, " "); // a space only
strcat(stringDeviceName, (char*) stringProduct);
//printf("%s\n", stringDeviceName);
/*
* Save them all into arrays
*/
product[deviceIndex] = deviceDescriptor.idProduct;
vendor[deviceIndex] = deviceDescriptor.idVendor;
memcpy(device[deviceIndex], stringDeviceName, 256 * 2 * sizeof(char));
/*
* Close and try next one.
*/
if (DEVICEHANDLE_NULL != NULL) {
libusb_close(DEVICEHANDLE_NULL);
DEVICEHANDLE_NULL = NULL;
}
/*
* Next USB device
*/
deviceIndex++;
}
/*
* Print our result what we found and send them to socket
*/
for (int i = 0; i < 11; i++) {
printf("Name: %s\n", device[i]);
printf("Vendor: %u\n", vendor[i]);
printf("Product: %u\n\n", product[i]);
}
libusb_exit(NULL);
return 0;
}