NTSTATUS SendHidReport(WDFDEVICE Device, HID_TOUCH_REPORT *report) { WDFMEMORY memory; WDF_MEMORY_DESCRIPTOR memDesc; WdfMemoryCreatePreallocated(WDF_NO_OBJECT_ATTRIBUTES, report, sizeof(HID_TOUCH_REPORT), &memory); WDF_MEMORY_DESCRIPTOR_INIT_BUFFER(&memDesc, report, sizeof(HID_TOUCH_REPORT)); return HidDevice_SubmitInterruptReadReport(Device, &memDesc); } To support calibration changes at runtime (e.g., from a user-mode calibration app), you implement a custom IOCTL handler:
Now, go forth and calibrate – down to the last raw I2C byte. References: Microsoft WDK Documentation, HID v1.11 Specification, I2C HID Guide, KMDF Tutorials. kmdf hid minidriver for touch i2c device calibration
VOID ApplyCalibration(RAW_TOUCH_REPORT *raw, HID_TOUCH_REPORT *calib, PCALIB_PARAMS params) { calib->X = (raw->RawX - params->XMin) * params->ScreenWidth / (params->XMax - params->XMin); calib->Y = (raw->RawY - params->YMin) * params->ScreenHeight / (params->YMax - params->YMin); // Clip to screen bounds if (calib->X > params->ScreenWidth) calib->X = params->ScreenWidth; if (calib->Y > params->ScreenHeight) calib->Y = params->ScreenHeight; } Advanced calibration uses an affine matrix for rotation, skew, and translation: Enter the
While many user-mode calibration tools exist, they suffer from latency, privilege constraints, and non-deterministic behavior. Enter the . By implementing a minidriver at the kernel level, you gain direct control over the I2C transport, real-time calibration parameter injection, and seamless integration with Windows’ Human Interface Device (HID) stack. other callbacks WdfDeviceCreateObject(Device
HID_DEVICE_CONFIG hidConfig; HID_DEVICE_CONFIG_INIT(&hidConfig); hidConfig.EvtHidDeviceGetDescriptor = TouchCalibEvtGetDescriptor; hidConfig.EvtHidDeviceGetAttributes = TouchCalibEvtGetAttributes; // ... other callbacks WdfDeviceCreateObject(Device, &attributes, (WDFOBJECT*)&hidDevice); Assume your raw touch data from I2C is 3 bytes per coordinate (X/Y pressure). You read a packet: