EVT_WDF_DEVICE_D0_ENTRY EvtDeviceD0Entry
You must include a specific report ID in your HID Descriptor for calibration data.
// User-mode application sends: HidD_SetFeature( handle, reportBuffer, // contains: command (READ_CALIBRATION) + offset + length bufferLength );
typedef struct _CALIBRATION_DATA INT32 A, B, C; INT32 D, E, F; INT32 Divisor; // Used for scaling fixed-point numbers CALIBRATION_DATA, *PCALIBRATION_DATA; void CalibrateCoordinates(PCALIBRATION_DATA CalData, INT32 RawX, INT32 RawY, PINT32 CalX, PINT32 CalY) if (CalData->Divisor == 0) *CalX = RawX; *CalY = RawY; return; // Fallback to raw data if uncalibrated *CalX = (CalData->A * RawX + CalData->B * RawY + CalData->C) / CalData->Divisor; *CalY = (CalData->D * RawX + CalData->E * RawY + CalData->F) / CalData->Divisor; Use code with caution. 4. Storing and Loading Calibration Data kmdf hid minidriver for touch i2c device calibration
By implementing a well-structured KMDF HID minidriver, developers can ensure that I2C touch devices are responsive and accurately calibrated, providing a seamless experience for Windows users.
// FEATURE: Load Calibration status = LoadCalibrationFromACPI(Device, &pDevCtx->CalibrationCache);
| Symptom | Likely Cause | Solution | |---------|--------------|----------| | Touch not working after boot | Calibration missing or corrupt | Validate I2C write during D0 entry | | Driver fails to start | I2C target not acquired | Wait for HIDI2C.sys to start (device relations) | | Calibration tool fails | Feature report size mismatch | Match HID report descriptor exactly | Storing and Loading Calibration Data By implementing a
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MyTouchCalib\Parameters] "X_Gain"=dword:3F800000 (float 1.0) "Y_Gain"=dword:3F800000 "X_Offset"=dword:00000000 "Y_Offset"=dword:00000000
Your minidriver handles IOCTL_HID_SET_FEATURE . Applying Calibration Data:
Touch screen calibration maps raw physical coordinates from the touch sensor to the pixel coordinates of the display panel. The Linear Calibration Matrix (3-Point Calibration) Testing and Validation
Always read I2C registers in large burst blocks rather than performing single-byte reads.
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// Send Request to ACPI (via WDF) status = WdfIoTargetSendIoctlSynchronously( WdfDeviceGetIoTarget(Device), NULL, IOCTL_ACPI_EVAL_METHOD_EX, ¶ms, sizeof(params), NULL, &returnLength );
To create a driver that supports calibration, the developer must implement EvtIoDeviceControl handlers within the KMDF HID minidriver.
Ycalibrated=(Yraw−MinY)×32767(MaxY−MinY)cap Y sub c a l i b r a t e d end-sub equals the fraction with numerator open paren cap Y sub r a w end-sub minus cap M i n cap Y close paren cross 32767 and denominator open paren cap M a x cap Y minus cap M i n cap Y close paren end-fraction Note: Windows uses a 0-32767 range for touchscreen input. 4. Testing and Validation
