我需要读取电机控制单元的响应。在写入以?开头的命令后，电机单元应该响应一些文本。即在?MSG它应该报告其状态。但是当我尝试读取状态时，设备什么都不发送，请求以超时结束。
代码非常简单，使用libusb。该程序将所有活动的驱动程序与设备分离，将其自身附加到设备，传输命令?MSG并等待响应。之后它分离并结束。
为什么没有回应？代码中是否有任何错误或是电机单元的问题？我确信当电机移动时，设备会发送和接收命令，例如PSET1=4000
#include <assert.h>
#include <string.h>
#define VENDOR_ID 0x0483
#define PRODUCT_ID 0x5740
#define BULK_EP_IN 0x03
#define BULK_EP_OUT 0x81 // From computer to control unit
#define INTERFACE_IN 0
#define INTERFACE_OUT 1
#define BUF_SIZE 64
int main()
{
libusb_context *ctx;
libusb_device_handle *dev_handle;
int r = 0;
int actual, length, received;
char cmd[] = "?MSG\r\n";
char buffer[BUF_SIZE];
length = strlen(cmd);
r = libusb_init(&ctx);
assert(r == 0);
/* Set verbosity level to 3, as suggested in the documentation */
libusb_set_debug(ctx, 3);
/* Get device handle */
dev_handle = libusb_open_device_with_vid_pid(ctx, VENDOR_ID, PRODUCT_ID);
assert(dev_handle != NULL);
/* Find out if kernel driver is attached on IN iface */
if(libusb_kernel_driver_active(dev_handle, INTERFACE_IN) == 1) {
printf("Kernel Driver Active\n");
assert(libusb_detach_kernel_driver(dev_handle, INTERFACE_IN) == 0);
printf("Kernel Driver Detached!\n");
}
if(libusb_kernel_driver_active(dev_handle, INTERFACE_OUT) == 1) {
printf("Kernel Driver Active\n");
assert(libusb_detach_kernel_driver(dev_handle, INTERFACE_OUT) == 0);
printf("Kernel Driver Detached!\n");
}
/* Claim IN interface of device */
r = libusb_claim_interface(dev_handle, INTERFACE_IN);
assert(r >= 0);
/* claim OUT interface of device */
r = libusb_claim_interface(dev_handle, INTERFACE_OUT);
assert(r >= 0);
/* Transfer commands */
r = libusb_bulk_transfer(dev_handle, BULK_EP_IN, (unsigned char *)cmd, length, &actual, 0);
assert(r == 0 && actual > 0 && actual == length);
printf("Written %s\n",cmd);
/* Now read response */
if (cmd[0] == '?') {
char buffer[BUF_SIZE] = "";
int received = 0;
do {
int i;
r = libusb_bulk_transfer(dev_handle, BULK_EP_OUT, (unsigned char *)buffer, BUF_SIZE, &received, 1000);
if(r == LIBUSB_ERROR_TIMEOUT) {
printf("Timeout\n");
} else {
assert(r == 0);
}
for(i = 0; i<BUF_SIZE;i++)
printf("%c",buffer[i]);
} while (received != 0);
}
/* Release devices */
r = libusb_release_interface(dev_handle, INTERFACE_IN);
assert(r == 0);
r = libusb_release_interface(dev_handle, INTERFACE_OUT);
assert(r == 0);
/* Clean */
libusb_close(dev_handle);
libusb_exit(ctx);
}
以下是设备sudo lsusb --verbose的说明，以防万一：
Bus 003 Device 003: ID 0483:5740 STMicroelectronics STM32F407
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 2 Communications
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x0483 STMicroelectronics
idProduct 0x5740 STM32F407
bcdDevice 1.00
iManufacturer 1 STMicroelectronics
iProduct 2 STR75x Virtual COM Port
iSerial 3 Demo 1.000
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 67
bNumInterfaces 2
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xc0
Self Powered
MaxPower 0mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 2 Communications
bInterfaceSubClass 2 Abstract (modem)
bInterfaceProtocol 1 AT-commands (v.25ter)
iInterface 0
CDC Header:
bcdCDC 1.10
CDC Call Management:
bmCapabilities 0x00
bDataInterface 1
CDC ACM:
bmCapabilities 0x02
line coding and serial state
CDC Union:
bMasterInterface 0
bSlaveInterface 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 255
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 10 CDC Data
bInterfaceSubClass 0 Unused
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x03 EP 3 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Device Status: 0x0001
Self Powered
答案 0 :(得分：0)
您可以通过RS-232协议与设备通信，因为它提供虚拟COM端口，它是 CDC ACM 类。内核驱动程序是cdc_acm。
iManufacturer 1 STMicroelectronics
iProduct 2 STR75x Virtual COM Port
bInterfaceClass 2 Communications
bInterfaceSubClass 2 Abstract (modem)
bInterfaceProtocol 1 AT-commands (v.25ter)
iInterface 0
CDC Header:
bcdCDC 1.10
CDC Call Management:
bmCapabilities 0x00
bDataInterface 1
CDC ACM:
bmCapabilities 0x02
line coding and serial state
CDC Union:
bMasterInterface 0
bSlaveInterface 1
因此，您可以通过向/dev/ttyACMx（或/dev/ttyUSBx）发送RS-232命令与设备通信（将x替换为您系统上的号码）
要检查此项，您可以使用终端程序，例如 PuTTY ，... 5 Linux / Unix Commands For Connecting To The Serial Console 。你必须弄清楚正确的COM端口设置（波特率，奇偶校验，开始/停止位等）
有几个RS-232库，请参阅 C: cross-platform RS-232 serial library?
检查设备插件后的dmesg输出，以查看使用的驱动程序。