## 2 Materials and Methods
### Testing Device Hardware  
The device used to test the chosen subjects is shown in Figure 2. The device itself is durable and easily transportable. The device is made of durable materials, such as aluminum and hardened plastic, which ensures the protection of the delicate electronics inside the device. The device in its disassembled state is placed in a transport case, which ensures easy handling and transfer of the device. The dimensions for inclusion in transport condition (Figure 3) are 35 \(\times\) 25 \(\times\) 17 cm. It consists of four main parts: the main module, with the integrated microcontroller (MCU) module and buttons placed in front of the tested subject, and from the foot pedals, a module that connects to the main module, as well as one from the headphones. The main module is connected to the USB port of a PC or a laptop that has the software application running and from this port it is also powered. The USB connection provides a virtual comport connection with a baud rate of 921,600 baud/s, 8-bit word, and one stop bit without parity.  
Figure 2: Photo of the testing device.  
The MCU uses an embedded module with NXP LPC1768 processor that is based on the ARM Cortex-M3 architecture and is running at 96 MHz. It has 32 KB RAM and 512 KB FLASH memories, which are sufficient for the tasks programmed in the C programming language that realize within the testing system. All the buttons, both the ones for visual (3 buttons) and for audio (10 buttons) tasks, and both pedals are connected to the MCU with pull-up resistors to define the initial state and suppress the possible interference from ambient electromagnetic fields.  
There are no timers used within the MCU; it simply reacts as fast as possible to in-puts and sends them to the PC or laptop; however, the button groups are logically handled as buses, to avoid accepting the situation in which more buttons from the same group are simultaneously pressed. Each button has its corresponding ASCII character from \"a\" to \"o\", which is sent if it is pressed, and to avoid sending multiple characters, the button needs to be released and again pressed to send another character; thus, the buttons are evaluated after a state change is detected. The safety time margin, when the buttons are non-responsive while the task changes from one type to another, was set to 0.2 s. When testing the device, it was found that the minimum response speed was measured at 0.3 s, and the device testing also showed that the buttons oscillated for up to 0.1 s, causing errors in the measurements. For this reason, the software set a minimum task time of 0.2 s, and the problems with the oscillation of the probes were thereby eliminated.  
The main result of the work is a technical device for measuring the relative error rate of students--air traffic controllers and pilots--during multitasking training, which consists of HW and SW parts. The basis of the measuring device is a suitably located input-output unit, which is connected in connection with the handling control unit. The manipulation control unit also includes buttons L, C, and R, which are used to enter tasks from movements entered in the manipulation area. Other signals entering the manipulation control unit are imported from the numeric keypad, containing buttons 0-9, which are used to enter the tasks of the acoustic commands. The tasks resulting from the pedipulation area enter the control unit from the left pedipulation unit and the right pedipulation unit. The verification device was designed to measure the reaction time in response to a randomly generated task. The technical solution of the device is shown on Figure 4.