For engineers developing touch solutions over the I2C (Inter-Integrated Circuit) bus, the challenge is twofold. First, the device must conform to Windows' HID (Human Interface Device) standards. Second, it must account for physical variances in the touch sensor, display lamination, and environmental drift. The most robust solution to these challenges is a specifically architected for I2C touch device calibration.
CalibratedPoint->X = (RawPoint->X * pContext->CoeffA) + (RawPoint->Y * pContext->CoeffB) + pContext->CoeffC; CalibratedPoint->Y = (RawPoint->X * pContext->CoeffD) + (RawPoint->Y * pContext->CoeffE) + pContext->CoeffF; kmdf hid minidriver for touch i2c device calibration
VOID ApplyCalibration(PTOUCH_POINT RawPoint, PTOUCH_POINT CalibratedPoint) For engineers developing touch solutions over the I2C
void EvtIoDeviceControl( WDFQUEUE Queue, WDFREQUEST Request, size_t OutputBufferLength, size_t InputBufferLength, ULONG IoControlCode) The most robust solution to these challenges is
// Configure I2C connection using resource list PVIDEO_PNP_DEVICE pDev = CreateDeviceContext(); To allow a user-mode calibration tool to interact with your driver, you must provide a private IOCTL. This is how the calibration GUI collects raw points and sends back coefficients.
In your KMDF driver, implement a EvtIoDeviceControl callback:
WDFKEY hKey; WdfDeviceOpenRegistry(Device, PLUGPLAY_REGKEY_DEVICE, &hKey); // Read REG_BINARY "CalibCoeffs" -> store in device context WdfRegistryClose(hKey); When user-mode sends SET_COEFFS , write back immediately to the registry.