Basic 8051 tutorial 2 2014-04-15

Ok... Back on track.

The next tutorial we need to read a 4 x 3 ( 12 key ) keypad...

If we attach a keypad to port 0 and place some resistors as external pull up’s we can read can read the 12 possible on the keypad on only 7 pins... 4 pins as columns and 3 pins as rows.. Here is the connection I used... I have included a 7 segment LED as a simple visual response...

View attachment 85580
The pinout is shown above... We don't have enough power to sink the current so I used a line...

Click to expand...