i would like to ask what is the best and efficient way to interface a membrane keypad in an LCD using a microcontroller. I plan to use a PIC16F877A.
i read some articles and i found out the traditional way to do this was that to directly connect the rows and columns of the keypad to the MCU and scan for a "1" to occur in a column (or row) first and scan again for a "1" in the row (or column next).
i also read about using a keypad encoder like the MM74C922. 1 MM74C922 is used for 1 LCD if i'm not mistaken.
i'm planning to interface several keypads in LCDs, about 5 -7 LCDs. so will using an MM74C922 be advisable considering the cost (1 MM74C922 for 1 LCD) ?
i want to know other methods to do this.
it would be nice to hear from you. any comments would be much appreciated. thanks guys. どうも