in ev3-api/src/ev3api_motor.c [315:333]
ER ev3_motor_stop(motor_port_t port, bool_t brake) {
ER ercd;
// lazy_initialize();
CHECK_PORT(port);
CHECK_PORT_CONN(port);
char buf[3];
buf[0] = opOUTPUT_STOP;
buf[1] = 1 << port;
buf[2] = brake;
motor_command(buf, sizeof(buf));
ercd = E_OK;
error_exit:
return ercd;
}