我需要读取电机控制单元的响应。在写入以 ? 开头的命令后，电机单元应响应一些文本。 IE。在 ?MSG 上它应该报告它的状态。但是，当我尝试读取状态时，设备什么也不发送，请求以超时结束。
代码非常简单并且使用了 libusb。该程序从设备上分离所有事件驱动程序，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。
为什么没有反应？代码有错误还是电机单元的问题？我确信命令是在电机移动时由设备发送和接收的，例如，在 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);
}
如果它很重要，这里是带有 sudo lsusb --verbose 的设备描述:
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
最佳答案
您可以通过 RS-232 协议(protocol)与设备通信，因为它提供了一个虚拟 COM 端口，这是一个 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 命令来与设备通信(将 x 替换为您的号码系统)
要检查这一点，您可以使用像 PuTTY 这样的终端程序。 ,... 5 Linux / Unix Commands For Connecting To The Serial Console 。您必须找出正确的 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?
在设备中插入插件后检查dmesg 输出以查看使用了哪个驱动程序。
关于c - 为什么使用 lsusb 读取失败？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41611073/