Kmdf Hid Minidriver For Touch I2c Device Calibration

This runs when the device powers up. This is the critical moment to apply calibration, as I2C devices often lose register state on power loss.

NTSTATUS EvtDeviceD0Entry(WDFDEVICE Device, WDF_POWER_DEVICE_STATE PreviousState) PDEVICE_CONTEXT pDevCtx = GetDeviceContext(Device); kmdf hid minidriver for touch i2c device calibration

// Define the HidGetCalibrationData routine NTSTATUS HidGetCalibrationData( _In_ WDFDEVICE Device, _Out_ PCALIBRATION_DATA CalibrationData ) This runs when the device powers up

// Translate: X' = a*X + b*Y + cx calibrated->X = (LONG)(cal->A * raw->X + cal->B * raw->Y + cal->Cx); calibrated->Y = (LONG)(cal->D * raw->X + cal->E * raw->Y + cal->Cy); // Clamp to touch resolution buffer[0] = CMD_WRITE_CALIBRATION

The driver updates its internal transformation matrix and writes the new values to the registry for the next boot. 5. Best Practices for I2C Touch Drivers

// Write new calibration memset(buffer, 0, sizeof(buffer)); buffer[0] = CMD_WRITE_CALIBRATION; memcpy(buffer + 1, newCalibData, calibSize); HidD_SetFeature(hDevice, buffer, sizeof(buffer));