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我正在尝试开发一个简单的程序以在固件更新模式下与 Nexus-4 引导加载程序进行通信。Nexus -4 有 3 个 USB 接口。Interface-1 有两个 2 端点 - 2 和 131。

我编写了一个程序来通过端点 2 编写命令 get-device-info，并在端点 131 处侦听以获取回复。（我尝试了接口和端点的所有排列！）。

程序成功将命令写入设备，但没有从设备中读取任何内容。

命令格式：Flag(0x7e)：CMD：数据（变长）：CRC-16：Flag(0x7e)

获取设备信息命令：0x7e 0x00 0x78 0xf0 0x7e

以下是程序。

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

#define INTERFACE 1
#define EP_OUT 2
#define EP_IN 131

int main() {

        libusb_device **devs; // retrieve a list of devices
    libusb_device_handle *dev_handle; // device handler
    libusb_context *ctx = NULL; //a libusb session

    int r, r2, i; 
    ssize_t cnt; //holding number of devices in list

    unsigned char data[30],read_data[512]; //data to write

    data[0]=0x7e;data[1]=0x00;data[2]=0x78;data[3]=0xf0;data[4]=0x7e; // get-device-info command in HLDC format

    int actual,read_actual; 

    r = libusb_init(&ctx); 

    if(r < 0) {
        printf("Init Error\n");
        return 1;
    }

    libusb_set_debug(ctx, 3); 

    cnt = libusb_get_device_list(ctx, &devs); //get the list of devices

    if(cnt < 0) {
        printf("Get Device Error\n");
        return 1;
    }
    printf("%d Devices in list\n",(int)cnt);

    dev_handle = libusb_open_device_with_vid_pid(ctx, 4100, 25371); //these are vendorID and productID I found for Nexus-4 firmware update

    if(dev_handle == NULL)
        printf("Cannot open device\n");
    else
        printf("Device opened\n");

    libusb_free_device_list(devs, 0); //free the device list


    if(libusb_kernel_driver_active(dev_handle, INTERFACE) == 1) { //find out if kernel driver is attached
        printf("Kernel Driver Active\n");
        if(libusb_detach_kernel_driver(dev_handle, INTERFACE) == 0) //detach it
            printf("Kernel Driver Detached!\n");
    }

    r = libusb_claim_interface(dev_handle, INTERFACE); //claim interface 1 Nexus-5/4 FUM
    if(r < 0) {
        printf("Cannot Claim Interface\n");
        printf("%s\n",libusb_error_name(r));
        return 1;
    }
    printf("Claimed Interface\n");

    printf("Data to be send -> %s\n",data); //just to see the data that we are writing 
    printf("Writing Data...\n");

    r = libusb_bulk_transfer(dev_handle, (EP_OUT | LIBUSB_ENDPOINT_OUT), data, 5, &actual, 0); 

    if(r == 0 && actual == 5){ //we wrote successfully 5 bytes to the device
        printf("Writing Successful!\n");

        printf("Waiting to read from device!\n");
        r2 = libusb_bulk_transfer(dev_handle, (EP_IN | LIBUSB_ENDPOINT_IN), read_data, 512, &read_actual, 5000); 

        if (r2 >=0){
            if (read_actual > 0){
                printf("Data received by bulk transfer\n");

                printf("Data is ");
                for (i=0; i<read_actual; i++)
                    printf("%x ",read_data[i]);
                printf("\n");
            }
            else{
                printf(stderr, "No data received in bulk transfer (%d)\n", r2);
                return -1;
            }
        }
        else{   
            fprintf(stderr, "Error receiving data via bulk transfer %d\n", r2);
            return r2;                                                      
        }
    }
    else
        printf("Write Error\n");

    r = libusb_release_interface(dev_handle, INTERFACE); //release the claimed interface
    if(r!=0) {
        printf("Cannot Release Interface\n");
        return 1;
    }
    printf("Released Interface\n");

    libusb_close(dev_handle); 
    libusb_exit(ctx); 

    return 0;
}

该程序能够成功地将命令发送到手机，但它无法接收到手机的任何响应。当我运行程序时，我得到以下输出：

列表中的 10 个设备

设备打开

内核驱动程序激活

内核驱动程序分离！

声称的接口

要发送的数据 -> ~

写入数据...

写作成功！

等待从设备读取！

通过批量传输接收数据时出错 -7

我不确定没有得到响应的原因是因为错误的命令结构还是因为程序的执行？

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0 回答 0