in ev3-api/src/ev3api_sensor.c [284:301]
int16_t ev3_ultrasonic_sensor_get_distance(sensor_port_t port) {
ER ercd;
// lazy_initialize();
CHECK_PORT(port);
CHECK_COND(ev3_sensor_get_type(port) == ULTRASONIC_SENSOR, E_OBJ);
#if 0
return ev3_uart_sensor_get_short(port) / 10;
#endif
int16_t val;
uart_sensor_fetch_data(port, US_DIST_CM, &val, sizeof(val));
return val / 10;
error_exit:
syslog(LOG_WARNING, "%s(): ercd %d", __FUNCTION__, ercd);
return 0;
}