qmk_firmware/keyboards/handwired/onekey/blackpill_f401/blackpill_f401.c

/* Copyright 2020 Sergey Vlasov (sigprof)
 *
 * 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 QMK_KEYBOARD_H

void board_init(void) {
    // B9 is configured as I2C1_SDA in the board file; that function must be
    // disabled before using B7 as I2C1_SDA.
    setPinInputHigh(B9);
}