OpenterfaceCore

Shared C library for Openterface KeyMod — keyboard, mouse, and macro packet building for the CH9329 HID-over-serial protocol.

What's here

Path	Purpose
include/keymod.h	Public API header
src/keymod.c	Implementation (HID codes, packet builders, token parser)
cli/keymod_cli.c	CLI demo / debugging tool
tests/keymod_test.c	Unit tests
ios/KeyModWrapper/	Swift wrapper for iOS integration
android/	JNI wrapper + Java helper for Android integration

API

Packet builders

uint8_t pkt[14];
km_build_keyboard(pkt, KM_MOD_CTRL, (uint8_t[]){0x06}, 1);  // Ctrl+C

uint8_t mpkt[11];
km_build_mouse_rel(mpkt, KM_MS_BTN_LEFT, 0, 0, 0);          // left click

uint8_t pr[28];
km_build_press_release(pr, KM_MOD_NONE, 0x28);              // Enter press+release

HID code lookup

int code = km_hid_code("Enter");           // 0x28
int code = km_hid_code_for_char('!', &s);  // 0x1E, s=1 (needs shift)

Macro parsing

km_parsed_token_t tokens[32];
int n = km_parse_macro("<CMD>V</CMD>", tokens, 32);
// tokens[0].hid_code = 0x19 (V), tokens[0].modifiers = KM_MOD_GUI

Build

mkdir build && cd build
cmake ..
make
./keymod_test      # unit tests
./keymod_cli       # demo output
./keymod_cli Enter # single key packet
./keymod_cli "<CTRL>C</CTRL>"  # macro packets

iOS integration

Add all .c files and include/keymod.h to your Xcode target. Create a bridging header that imports OpenterfaceCore.h. Use KeyModPacker from Swift:

let packet = KeyModPacker.keyboard(modifiers: KeyModModifier.ctrl, keys: [0x06])
bleManager.sendTouchData(data: packet)

Android integration

Add the JNI CMake to your app/build.gradle:

android {
    externalNativeBuild {
        cmake {
            path "../../Openterface_Core/android/CMakeLists.txt"
        }
    }
}

Copy KeyModLib.java into your package. Call from Java:

byte[] packet = KeyModLib.buildKeyboardPacket(KeyModLib.MOD_CTRL, new byte[]{0x06});
bluetoothService.sendData(packet);

Protocol

All packets use the CH9329 format:

• Keyboard (14 bytes): 57 AB 00 02 08 | mod | 00 | k1..k6 | checksum
• Mouse rel (11 bytes): 57 AB 00 05 05 | 01 | btn | dx | dy | wheel | checksum
• Checksum: sum of all bytes except last, masked to 8 bits