I have used some I2C matrix keypads before on the Arduino with I2C. But now, I’m trying to reuse an old piece of hardware which I would like to conserve the front panel for aesthetics.
The problem is, looking at the schematics, it seems to be 17 (+1 unused) keys in total, all of them connected to a PCF8574T chip. I tried to use the keypad_I2C library to no avail, since I get strange behaviour like misaligned rows.
The schematic of the keypad is as follows:
So, I understand that the matrix should be as this:
As you can see, there is a column that doesn’t have a pin connected. I suppose that maybe that row is triggered with a LOW input since instead of having a common input to the IC, it has a ground. But how can I implement this to the code? Any idea that could guide me would be appreciated
Thank you very much!