Keymatrix with Raspberry and PCF8574 (c#)

Question

Has anyone managed to run a matrix keyboard via i2c? I'm trying to use it via the PCF8574 expansion card.

In my case I use a 4x4 matrix keyboard. The ShowKeyMatrixEvent event actually fires 3 times, for each row that is not affected: really impractical. Do you know any alternatives? Even using another expansion chip.

Thank you

var settings = new System.Device.I2c.I2cConnectionSettings(1, Convert.ToInt32(_appSettings.KeyPad.i2cAddress, 16));
var i2cDevice = System.Device.I2c.I2cDevice.Create(settings);
var pcf8574 = new Iot.Device.Pcx857x.Pcf8574(i2cDevice);
GpioController gpio = new GpioController(PinNumberingScheme.Logical, pcf8574);
IEnumerable<int> outputs = new int[] { 0, 1, 2, 3 };
IEnumerable<int> inputs = new int[] { 4, 5, 6, 7 };
KeyMatrix keyMatrix = new KeyMatrix(outputs, inputs, TimeSpan.FromMilliseconds(10), gpio, true);
keyMatrix.KeyEvent += KeyMatrixEventReceived;
keyMatrix.StartListeningKeyEvent();


void ShowKeyMatrixEvent(KeyMatrix sender, KeyMatrixEvent pinValueChangedEventArgs)
{
    Console.WriteLine($"{DateTime.Now:yyyy/MM/dd HH:mm:ss.fff} {pinValueChangedEventArgs.Output}, {pinValueChangedEventArgs.Input}, {pinValueChangedEventArgs.EventType}");
    Console.WriteLine();
}

By pressing a key and releasing it I therefore obtain 3 distinct events, one for each excluded row. For example, by pressing key 1 (and holding it down), I get 3 falling and rising events: one for each excluded row.

If I increase the delay, I risk not intercepting the excluded lines. In any case, this doesn't have to be the solution: I was hoping there was a way to have the single button pressed, without having to think by exclusion.

2023-11-21 19:53:37.3807|0|INFO|ShowKeyMatrixEvent|2023/11/21 19:53:37.380 2, 0, Falling 
2023-11-21 19:53:37.7867|0|INFO|ShowKeyMatrixEvent|2023/11/21 19:53:37.786 3, 0, Falling 
2023-11-21 19:53:38.3961|0|INFO|ShowKeyMatrixEvent|2023/11/21 19:53:38.396 1, 0, Falling 
2023-11-21 19:53:39.6118|0|INFO|ShowKeyMatrixEvent|2023/11/21 19:53:39.611 2, 0, Rising 
2023-11-21 19:53:40.0168|0|INFO|ShowKeyMatrixEvent|2023/11/21 19:53:40.016 3, 0, Rising 
2023-11-21 19:53:40.6245|0|INFO|ShowKeyMatrixEvent|2023/11/21 19:53:40.624 1, 0, Rising