Digital preset circuit and the 128 buttons keypad scanning circuit

Published:2011/6/20 0:50:00 Author:TaoXi | Keyword: Digital preset, 128 buttons, keypad scanning | From:SeekIC

The digital preset circuit The function of this circuit: it changes the keyboard pressing signal into the 2-bit BCD code and stores the code. Figure 1 is the logic diagram of this coding and storage circuit. Keypad scanning circuit In the last example, the keyboard scale is small, it has only ten keys (0-9). If the keyboard scale is large, by using the priority encoders to realize the coding will not economic any more. So people design the keypad scanning circuit. Figure shows the 128 keys scanning encoder.



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