qmk_firmware/keyboards/handwired/trackpoint/config.h

#ifndef CONFIG_H
    #define CONFIG_H

    #include "config_common.h"

    #define VENDOR_ID       0x1234
    #define PRODUCT_ID      0x5678
    #define DEVICE_VER      0x0001
    #define MANUFACTURER    QMK
    #define PRODUCT         TRACKPOINT-DEMO
    #define DESCRIPTION     Simple demonstration for IBM Trackpoint integration

    #define MATRIX_ROWS 1
    #define MATRIX_COLS 3

    #ifdef PS2_USE_USART
        #define PS2_CLOCK_PORT  PORTD
        #define PS2_CLOCK_PIN   PIND
        #define PS2_CLOCK_DDR   DDRD
        #define PS2_CLOCK_BIT   5
        #define PS2_DATA_PORT   PORTD
        #define PS2_DATA_PIN    PIND
        #define PS2_DATA_DDR    DDRD
        #define PS2_DATA_BIT    2

        /* synchronous, odd parity, 1-bit stop, 8-bit data, sample at falling edge */
        /* set DDR of CLOCK as input to be slave */
        #define PS2_USART_INIT() do {   \
            PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT);   \
            PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT);     \
            UCSR1C = ((1 << UMSEL10) |  \
                      (3 << UPM10)   |  \
                      (0 << USBS1)   |  \
                      (3 << UCSZ10)  |  \
                      (0 << UCPOL1));   \
            UCSR1A = 0;                 \
            UBRR1H = 0;                 \
            UBRR1L = 0;                 \
        } while (0)
        #define PS2_USART_RX_INT_ON() do {  \
            UCSR1B = ((1 << RXCIE1) |       \
                      (1 << RXEN1));        \
        } while (0)
        #define PS2_USART_RX_POLL_ON() do { \
            UCSR1B = (1 << RXEN1);          \
        } while (0)
        #define PS2_USART_OFF() do {    \
            UCSR1C = 0;                 \
            UCSR1B &= ~((1 << RXEN1) |  \
                        (1 << TXEN1));  \
        } while (0)
        #define PS2_USART_RX_READY      (UCSR1A & (1<<RXC1))
        #define PS2_USART_RX_DATA       UDR1
        #define PS2_USART_ERROR         (UCSR1A & ((1<<FE1) | (1<<DOR1) | (1<<UPE1)))
        #define PS2_USART_RX_VECT       USART1_RX_vect
    #endif

    #define MATRIX_COL_PINS { F1, F4, F5 }
    #define MATRIX_ROW_PINS { F0 }
    #define UNUSED_PINS

    /* COL2ROW or ROW2COL */
    #define DIODE_DIRECTION COL2ROW

    #define DEBOUNCING_DELAY 5

    #define LOCKING_SUPPORT_ENABLE
    #define LOCKING_RESYNC_ENABLE

    /* key combination for command */
    #define IS_COMMAND() ( \
        keyboard_report->mods == (MOD_BIT(KC_LSHIFT) | MOD_BIT(KC_RSHIFT)) \
    )

#endif