start = g_get_monotonic_time();
while (g_get_monotonic_time() - start < MAX_SCAN_TIME_US) {
if (serial_read_nonblocking(serial, &c, 1) == 1 && c == 0xa5) {
start = g_get_monotonic_time();
while (g_get_monotonic_time() - start < MAX_SCAN_TIME_US) {
if (serial_read_nonblocking(serial, &c, 1) == 1 && c == 0xa5) {