first example of a graphic code with all the directions set as active and a second example of only directions of east, southeast, southwest, west and north set as active, respectively. 

I n the digital code embodiment, each direction is treated as one digit of an octal code, i.e., from 0 to 7. To set the code, one slides each direction in a specific order. Then to trigger the code, one slides all the selected directions in the same order. Thus to successfully enter the code, one needs to remember both the numbers (directions) and the order. It can be seen that the digital code system is more similar to a traditional code system and it offers a higher safety level compared to the graphic code. Figure 15(b) and (c) show two examples of time- domain signals for digital codes: one with "01234567" as the code and one with "05124007" as the code. 

I n certain embodiments, the interface 1200 can be configured into one of the above two code systems according to the usage requirements and user’s preference. 

An example of a sixteen-direction 0/1-coding interface 1600 with 4-bit binary code is shown in Figure 16(a). Figures 16(c,d) depict the corresponding output signals from the sixteen directions, showing the 4-bit binary coded electrodes between the two reference (beginning and end) electrodes can be differentiated according to the time-domain output peaks. 

I n addition to the security code system described above, the sixteen-direction interface can also be used for Binary Coded Decimal (BCD) and other functions, as illustrated in Figure 16(b). For instance, the sixteen-direction interface can be used to set the spatial coordinates of a point (15, 35, 22) by consecutively sliding across direction 14, 13, 2, 6, 15, 13, 4, 6, 16, 13, 3 and 3 ("X" "=" "1" "$_{2}$ " "2"). i n another example, the sensor 1600 can function as the input interface of a calculator, e.g., to calculate the result of "- 138-56+31=" by consecutively sliding across direction 12, 2, 4, 9, 12, 6, 7, 11, 4, 2 and 13 ("-" "1" "3" "8" "-" "5" "6" "+" "3" "1" "="), as depicted in Figure 38. The sixteen-direction interface 1600 can be used to provide each digit of a 

