Hallo

I must read a 4x4 matrix keybord using PCF8574 (please don't replay that it's a bad solution, I already read some threads on this forum, but I can't change anything to the project). I chose P0-P3 for the rows and P4-P7 for the columns. I scan the keyboard cycling a 0 on the row lines, keeping 1's on the columns and reading the port lines when PCF8574 signal with /INT. The problem that I have is that the chip don't signal always the event (key pressed or depressed) and I belive that direct connection from row line with column line, through pressed keys, it's not the best solution. Now, please, if anybody know how to connect such matrix in a way that all pressed keys to be sensed, please let me know.
Thank you