Kmdf Hid Minidriver For Touch I2c - Device Calibration
When an internal device control request arrives with the control code IOCTL_HID_READ_REPORT , the driver reads the coordinate coordinates from the hardware line, calculates the calibration parameters, and alters the output buffer.
NTSTATUS SendI2CCommand(WDFIOTARGET I2CTarget, UCHAR reg, UCHAR value)
Below is a simplified architectural framework of a KMDF HID minidriver demonstrating coordinate transformation calibration inside an internal I/O queue read wrapper. 1. Driver and Device Initialization
#define IOCTL_SET_CALIBRATION CTL_CODE(FILE_DEVICE_UNKNOWN, 0x800, METHOD_BUFFERED, FILE_ANY_ACCESS) kmdf hid minidriver for touch i2c device calibration
Electromagnetic interference (EMI) from internal power supplies, processors, or wireless chips that warps the capacitive field.
The KMDF HID minidriver for touch I2C device calibration consists of the following components:
Windows relies on the Kernel-Mode Driver Framework (KMDF) and the Human Interface Device (HID) protocol to communicate with Touch I2C devices like tablets, trackpads, and interactive screens. Over time, or due to manufacturing variances, touch screens experience drift, offset issues, or dead zones. When an internal device control request arrives with
If you are reviewing this driver for a system with touch issues, follow these verification steps: Touch screen is horizontally inverted - Microsoft Q&A
To understand where our solution fits, let’s dissect the Windows HID architecture.
0x05, 0x0D, // Usage Page (Digitizer) 0x09, 0x04, // Usage (Touch Screen) 0xA1, 0x01, // Collection (Application) 0x85, 0x01, // Report ID 1 0x09, 0x22, // Usage (Finger) 0xA1, 0x00, // Collection (Physical) 0x09, 0x42, // Usage (Tip Switch) 0x15, 0x00, // Logical Minimum (0) 0x25, 0x01, // Logical Maximum (1) 0x75, 0x01, // Report Size (1) 0x95, 0x01, // Report Count (1) 0x81, 0x02, // Input (Data,Var,Abs) 0x09, 0x30, // Usage (X) 0x27, 0xFF, 0xFF, 0x00, 0x00, // Logical Maximum (65535) 0x75, 0x10, // Report Size (16) 0x95, 0x01, // Report Count (1) 0x81, 0x02, // Input (Data,Var,Abs) ... etc ... 0xC0, 0xC0 If you are reviewing this driver for a
Kernel Driver Engineering Version: 1.0 Target Platform: Windows 10/11 (x64, ARM64)
Assume your raw touch data from I2C is 3 bytes per coordinate (X/Y pressure). You read a packet:
A KMDF HID minidriver:
The most common approach is storing the transformation coefficients in the device's hardware registry key. During driver initialization ( EvtDevicePrepareHardware ), the driver reads these parameters:
Touchscreens and touchpads relying on the I2C (Inter-Integrated Circuit) protocol are standard in modern computing. To interface these devices with Windows, developers use the Kernel-Mode Driver Framework (KMDF) to implement a Human Interface Device (HID) minidriver.