In the matrix keyboard, each horizontal and vertical line is not directly connected to the intersection, but to the key. So, port, for example, a P1 port) can create a button 4 * 4 = 16, which is more than twice the port line, directly used for the keyboard, and more lines, More obvious differences, such as adding an extra row. You can create a 20 key keyboard, and directly use a port line that can only have another key) 9. You can see that when the number of keys required is relatively large, it is reasonable to use the matrix method as the keyboard.<br>
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