Lots of keys (100 or more) using 3 pins 4017 IC switch matrix controller and library. Up to 100 switches with 3 pins! - Exhibition / Gallery - Arduino Forum
This is the probably same or similar as the 4017 mentioned above.
Lots of keys (100 or more) using 3 pins 4017 IC switch matrix controller and library. Up to 100 switches with 3 pins! - Exhibition / Gallery - Arduino Forum
This is the probably same or similar as the 4017 mentioned above.