LCD is comprised of 8 data pins and 3 control pins(rs,rw,en) Total 8+3=11. Keypad 4×4 contains 4 Rows and 4 Coulombs Total 4+4=8. Now for this scenario given above you need Total 11+8=19 Pins and arduino uno only have 12 digital input output pins. So we have to add some more pins to arduino.
Increasing digital I/O pins of Arduino – Solution
Increasing arduino digital pins with 8255 diy project
Increasing digital input/output pins of arduino code
Filed Under: Arduino, Microcontroller Projects