switch(IoControlCode) case IOCTL_TOUCH_CALIBRATE_SET_COEFFS: // Lock mutex, copy coefficients into device context, apply to next touch // Store in registry via WdfRegistry break; case IOCTL_TOUCH_CALIBRATE_GET_RAW: // Temporarily bypass calibration, read raw I2C registers, return break;
void EvtIoDeviceControl( WDFQUEUE Queue, WDFREQUEST Request, size_t OutputBufferLength, size_t InputBufferLength, ULONG IoControlCode) kmdf hid minidriver for touch i2c device calibration
Define a custom IOCTL in your header:
For sealed systems, consider writing coefficients directly to the I2C device's EEPROM. This requires an additional vendor-specific I2C command. Part 6: User-Mode Calibration Application – The Companion Tool Your KMDF driver alone cannot perform calibration; it only applies it. A user-mode application must guide the user, collect points, compute coefficients, and call DeviceIoControl . A user-mode application must guide the user, collect
CalibratedPoint->X = (RawPoint->X * pContext->CoeffA) + (RawPoint->Y * pContext->CoeffB) + pContext->CoeffC; CalibratedPoint->Y = (RawPoint->X * pContext->CoeffD) + (RawPoint->Y * pContext->CoeffE) + pContext->CoeffF; and call DeviceIoControl . CalibratedPoint->
#define IOCTL_TOUCH_CALIBRATE_SET_COEFFS \ CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800, METHOD_BUFFERED, FILE_ANY_ACCESS) #define IOCTL_TOUCH_CALIBRATE_GET_RAW CTL_CODE(FILE_DEVICE_UNKNOWN, 0x801, METHOD_BUFFERED, FILE_ANY_ACCESS)
// 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.