qmk-firmware/docs/custom_matrix.md

Custom Matrix

QMK provides a mechanism to supplement or replace the default matrix scanning routine with your own code.

The reasons to use this feature include:

• Extra hardware between the keyboard's switches and MCU pins
  • I/O multiplexer
  • Line decoder
• Irregular switch matrix
  • Simultaneous use of COL2ROW and ROW2COL

Prerequisites

Implementing custom matrix usually involves compilation of an additional source file. It is recommended that for consistency, this file is called matrix.c.

Add a new file to your keyboard directory:

keyboards/<keyboard>/matrix.c

And to configure compilation for the new file, add this to your rules.mk:

SRC += matrix.c

'lite'

Provides a default implementation for various scanning functions, reducing the boilerplate code when implementing custom matrix. To configure it, add this to your rules.mk:

CUSTOM_MATRIX = lite

And implement the following functions in a matrix.c file in your keyboard folder:

void matrix_init_custom(void) {
    // TODO: initialize hardware here
}

bool matrix_scan_custom(matrix_row_t current_matrix[]) {
    bool matrix_has_changed = false;

    // TODO: add matrix scanning routine here

    return matrix_has_changed;
}

Full Replacement

When more control over the scanning routine is required, you can choose to implement the full scanning routine. To configure it, add this to your rules.mk:

CUSTOM_MATRIX = yes

And implement the following functions in a matrix.c file in your keyboard folder:

matrix_row_t matrix_get_row(uint8_t row) {
    // TODO: return the requested row data
}

void matrix_print(void) {
    // TODO: use print() to dump the current matrix state to console
}

void matrix_init(void) {
    // TODO: initialize hardware and global matrix state here

    // Unless hardware debouncing - Init the configured debounce routine
    debounce_init(MATRIX_ROWS);

    // This *must* be called for correct keyboard behavior
    matrix_init_quantum();
}

uint8_t matrix_scan(void) {
    bool matrix_has_changed = false;

    // TODO: add matrix scanning routine here

    // Unless hardware debouncing - use the configured debounce routine
    debounce(raw_matrix, matrix, MATRIX_ROWS, changed);

    // This *must* be called for correct keyboard behavior
    matrix_scan_quantum();

    return matrix_has_changed;
}

And also provide defaults for the following callbacks:

__attribute__((weak)) void matrix_init_kb(void) { matrix_init_user(); }

__attribute__((weak)) void matrix_scan_kb(void) { matrix_scan_user(); }

__attribute__((weak)) void matrix_init_user(void) {}

__attribute__((weak)) void matrix_scan_user(void) {}