USB HID Device on STM32
An Introduction to USB-HID
A Descriptor is a complete data structure that can be implemented through programming languages such as C, and stored in a USB device. It is used to describe all the attributes of a USB device, and the USB host requests this information through a series of commands. There are 5 standard descriptors for USB: device descriptor, configuration descriptor, string descriptor, interface descriptor, and endpoint descriptor.
The HID descriptor is associated with an interface (not an endpoint), so the device does not need to provide a HID descriptor for each endpoint.
Device descriptor
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | struct _DEVICE_DEscriptOR_STRUCT{ BYTE bLength; //設備描述符的字節數大小 BYTE bDescriptorType; //描述符類型編號，爲0x01 WORD bcdUSB; //USB版本號 BYTE bDeviceClass; //USB分配的設備類代碼，0x01~0xfe爲標準設備類，0xff爲廠商自定義類型，0x00不是在設備描述符中定義的，如HID BYTE bDeviceSubClass; //usb分配的子類代碼，同上，值由USB規定和分配的，HID設備此值爲0 BYTE bDeviceProtocl; //USB分配的設備協議代碼，同上HID設備此值爲0 BYTE bMaxPacketSize0; //端點0的最大包的大小 WORD idVendor; //廠商編號 WORD idProduct; //產品編號 WORD bcdDevice; //設備出廠編號 BYTE iManufacturer; //描述廠商字符串的索引 BYTE iProduct; //描述產品字符串的索引 BYTE iSerialNumber; //描述設備序列號字符串的索引 BYTE bNumConfiguration; //可能的配置數量} |
Configuration descriptor
1 2 3 4 5 6 7 8 9 10 11 12 13 | struct _CONFIGURATION_DEscriptOR_STRUCT{ BYTE bLength; //配置描述符的字節數大小 BYTE bDescriptorType; //描述符類型編號，爲0x02 WORD wTotalLength; //配置所返回的所有數量的大小 BYTE bNumInterface; //此配置所支持的接口數量 BYTE bConfigurationVale; //Set_Configuration命令需要的參數值 BYTE iConfiguration; //描述該配置的字符串的索引值 BYTE bmAttribute; //供電模式的選擇 BYTE MaxPower; //設備從總線提取的最大電流} |
String descriptor
1 2 3 4 5 6 7 8 9 | struct _STRING_DEscriptOR_STRUCT{BYTE bLength; //字符串描述符的字節數大小BYTE bDescriptorType; //描述符類型編號，爲0x03BYTE SomeDescriptor[36]; //UNICODE編碼的字符串} |
Interface descriptor
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | struct _INTERFACE_DEscriptOR_STRUCT{BYTE bLength; //接口描述符的字節數大小BYTE bDescriptorType; //描述符類型編號，爲0x04BYTE bInterfaceNunber; //接口的編號BYTE bAlternateSetting;//備用的接口描述符編號BYTE bNumEndpoints; //該接口使用端點數，不包括端點0BYTE bInterfaceClass; //接口類型 HID設備此值爲0x03BYTE bInterfaceSubClass;//接口子類型 HID設備此值爲0或者1BYTE bInterfaceProtocol;//接口所遵循的協議BYTE iInterface; //描述該接口的字符串索引值} |
Endpoint descriptor
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | struct _ENDPOIN_DEscriptOR_STRUCT{BYTE bLength; //端點描述符的字節數大小BYTE bDescriptorType; //描述符類型編號，爲0x05BYTE bEndpointAddress; //端點地址及輸入輸出屬性BYTE bmAttribute; //端點的傳輸類型屬性WORD wMaxPacketSize; //端點收、發的最大包的大小BYTE bInterval; //主機查詢端點的時間間隔} |
HID read/write devices.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | INT CHidUsb::WriteDevice(HANDLE hUsbDevice, const CHAR *lpszBuf, INT nSize, BOOL bNeedRead){ DWORD dwSizeWritten; OVERLAPPED OverLapped; DWORD dwErrCode; INT nWriteSize; INT nNeedWriteSize; CHAR szHidBuf[HID_PACKAGE_SIZE + 1]; nNeedWriteSize = nSize; nWriteSize = 0; // 只能已HID包的格式發送 memset(&OverLapped, 0, sizeof(OverLapped)); OverLapped.hEvent = m_hWriteEvent; while (1) { if (nSize < 0) { break; } nNeedWriteSize = HID_PACKAGE_SIZE; if (nNeedWriteSize > nSize) { nNeedWriteSize = nSize; } nSize -= nNeedWriteSize; memset(szHidBuf, 0xff, HID_PACKAGE_SIZE + 1); <span style="color:#ff0000;">szHidBuf[0] = 0</span>;// 這裏一定不要忘記，這個是ID，定義爲0，所以加上64個字節，所以一次操作爲65個字節 memcpy(szHidBuf + 1, lpszBuf, nNeedWriteSize); lpszBuf += nNeedWriteSize; <span style="color:#ff0000;">if (!::WriteFile(m_hUsbDevice, szHidBuf, HID_PACKAGE_SIZE + 1, &dwSizeWritten, &OverLapped))</span> { dwErrCode = GetLastError(); break; } assert(dwSizeWritten == HID_PACKAGE_SIZE + 1); nWriteSize += dwSizeWritten; } if (bNeedRead) { SetEvent(m_hWaitEvent); } return nWriteSize;} |