Computer Interfacing

Computer interfacing

ously at the clock rate. As only one flip-flop was set, the

data will consist of a single 1 and n -

1

zeros (when n is

the number of stages of the register).

In the case of a 64-key keyboard, the matrix would be

organised as an 8 x 8 layout — eight columns and eight

rows.

A scan pattern on the columns and rows could be

generated by an 8-stage ring counter for the columns and

& 1 of 8 selector for the rows. However, there is an im-

portant point here; either the columns ring counter must

be clocked at eight times the rate at which the 1 of 8

selector is clocked, or vice-versa. For example, if the rows

are clocked at a frequenc ...