qmk_firmware/keyboards/centromere/matrix.c

/*
Copyright 2012 Jun Wako
Copyright 2014 Jack Humbert

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "matrix.h"
#include "uart.h"

#define UART_MATRIX_RESPONSE_TIMEOUT 10000

void matrix_init_custom(void) {
    uart_init(500000);
}

bool matrix_scan_custom(matrix_row_t current_matrix[]) {
    uint32_t timeout = 0;
    bool changed = false;

    //the s character requests the RF remote slave to send the matrix information
    uart_write('s');

    //trust the external keystates, erase the last set of data
    uint8_t uart_data[11] = {0};

    //there are 10 bytes corresponding to 1w columns, and an end byte
    for (uint8_t i = 0; i < 11; i++) {
        //wait for the serial data, timeout if it's been too long
        while (!uart_available()) {
            timeout++;
            if (timeout > UART_MATRIX_RESPONSE_TIMEOUT) {
                break;
            }
        }

        if (timeout < UART_MATRIX_RESPONSE_TIMEOUT) {
            uart_data[i] = uart_read();
        } else {
            uart_data[i] = 0x00;
        }
    }

    //check for the end packet, the key state bytes use the LSBs, so 0xE0
    //will only show up here if the correct bytes were recieved
    if (uart_data[10] == 0xE0) {
        //shifting and transferring the keystates to the QMK matrix variable
        for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
            matrix_row_t current_row = (uint16_t) uart_data[i * 2] | (uint16_t) uart_data[i * 2 + 1] << 5;
            if (current_matrix[i] != current_row) {
                changed = true;
            }
            current_matrix[i] = current_row;
        }
    }

    return changed;
}