Kmdf Hid Minidriver For Touch I2c Device Calibration !!top!! -

typedef struct _RAW_TOUCH_REPORT { UCHAR TouchID; USHORT RawX; USHORT RawY; UCHAR Pressure; } RAW_TOUCH_REPORT; Calibration parameters could be stored in the registry, e.g.:

X_cal = A * X_raw + B * Y_raw + C Y_cal = D * X_raw + E * Y_raw + F This corrects for misaligned sensor grids. Most I2C touch controllers assert an interrupt GPIO when data is ready. In KMDF, you create a passive-level interrupt: kmdf hid minidriver for touch i2c device calibration

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: HID_TOUCH_REPORT *report) { WDFMEMORY memory

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. from a user-mode calibration app)

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TouchCalibMini\Parameters] "CalibMatrix"=hex:01,00,00,00,... A simple linear calibration:

NTSTATUS TouchCalibEvtIoDeviceControl(WDFQUEUE Queue, WDFREQUEST Request, ...) { switch (ControlCode) { case IOCTL_SET_TOUCH_CALIBRATION: // Read calibration matrix from user buffer WdfRequestRetrieveInputBuffer(Request, sizeof(CALIB_PARAMS), ¶ms, &length); // Store in device context safely WdfDeviceGetDeviceContext(Device)->CalibParams = updatedParams; break; } } The user-mode calibration tool can then call DeviceIoControl to update coefficients without a driver reload. For a multi-touch device, your HID Report Descriptor must conform to the Windows Precision Touchpad (PTP) or HID-over-I2C v1.0 spec. A minimal single-touch descriptor:

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: