Coding example

AN2328

2/7

1

Coding example

1.1

Load HID library

A dynamic loading hid library is used.

//Pointers to a function are used, therefore:

typedef VOID

(__stdcall *PHidD_GetProductString)(HANDLE, PVOID, ULONG);

typedef VOID

(__stdcall *PHidD_GetHidGuid)(LPGUID);

typedef BOOLEAN (__stdcall *PHidD_GetAttributes)(HANDLE, PHIDD_ATTRIBUTES);

typedef BOOLEAN (__stdcall *PHidD_SetFeature)(HANDLE, PVOID, ULONG);

typedef BOOLEAN (__stdcall *PHidD_GetFeature)(HANDLE, PVOID, ULONG);

HINSTANCE

hHID

= NULL;

PHidD_GetProductString

HidD_GetProductString

= NULL;

PHidD_GetHidGuid

HidD_GetHidGuid

= NULL;

PHidD_GetAttributes

HidD_GetAttributes

= NULL;

PHidD_SetFeature

HidD_SetFeature

= NULL;

PHidD_GetFeature

HidD_GetFeature

= NULL;

//Load the library:

hHID = LoadLibrary("HID.DLL");

//Update the pointers:

HidD_GetProductString = (PHidD_GetProductString)

GetProcAddress(hHID, "HidD_GetProductString");

HidD_GetHidGuid

= (PHidD_GetHidGuid)

GetProcAddress(hHID, "HidD_GetHidGuid");

HidD_GetAttributes

= (PHidD_GetAttributes)

GetProcAddress(hHID, "HidD_GetAttributes");

HidD_SetFeature

= (PHidD_SetFeature)

GetProcAddress(hHID, "HidD_SetFeature");

HidD_GetFeature

= (PHidD_GetFeature)

GetProcAddress(hHID, "HidD_GetFeature");

1.2

Lookup device

typedef struct _HIDD_ATTRIBUTES

{

ULONG

Size;

// = sizeof (struct _HIDD_ATTRIBUTES)

USHORT

VendorID;

USHORT

ProductID;

USHORT

VersionNumber;

} HIDD_ATTRIBUTES, *PHIDD_ATTRIBUTES;

GUID HidGuid;

(HidD_GetHidGuid)(&HidGuid);

HDEVINFO hDevInfo;

HANDLE DeviceHandle;

//Get information about HIDs

try {

hDevInfo = SetupDiGetClassDevs

(&HidGuid,NULL,NULL,DIGCF_PRESENT|DIGCF_INTERFACEDEVICE);

if (hDevInfo == INVALID_HANDLE_VALUE)

return 0;

} catch (...) {