static char at_client_getchar(void) { char ch; while (rt_device_read(at_client_local->device, 0, &ch, 1) == 0) { rt_sem_take(at_client_local->rx_notice, RT_WAITING_FOREVER); rt_sem_control(at_client_local->rx_notice, RT_IPC_CMD_RESET, RT_NULL); } return ch; } Author ...