In C `1` means one of **int** type which is **16bit** in case of AVR so you can't shift left more than 15. You will get unexpected zero when you say `1<<16`. You have to use **unsigned long** type with `1UL`.
http://deskthority.net/workshop-f7/rebuilding-and-redesigning-a-classic-thinkpad-keyboard-t6181-60.html#p146279
In C `1` means one of **int** type which is **16bit** in case of AVR so you can't shift left more than 15. You will get unexpected zero when you say `1<<16`. You have to use **unsigned long** type with `1UL`.
http://deskthority.net/workshop-f7/rebuilding-and-redesigning-a-classic-thinkpad-keyboard-t6181-60.html#p146279