The specification says that A6, A7 on Arduino Nano can only be used for analog inputs. Indeed, when I (not reading thoroughly the ATMEL spec) used A6, A7 as rows in Keypad setup, the whole sketch stopped to work (even reading from read digital inputs).
However if the HW provides pull-up resistors, even A6, A7 can be used as rows in the keypad matrix input, at the cost of some ifs in pin_mode etc. I'll prepare subclass of Keypad to allow for processing analog inputs.
The specification says that A6, A7 on Arduino Nano can only be used for analog inputs. Indeed, when I (not reading thoroughly the ATMEL spec) used A6, A7 as rows in Keypad setup, the whole sketch stopped to work (even reading from read digital inputs).
However if the HW provides pull-up resistors, even A6, A7 can be used as rows in the keypad matrix input, at the cost of some ifs in pin_mode etc. I'll prepare subclass of Keypad to allow for processing analog inputs.