ModulinoKnob: report error and not last valid _pressed if read() fails

[facchinm]

Modulino/src/Modulino.h

Lines 273 to 275 in cf5e2b2

	bool isPressed() {
	get();
	return _pressed;

[AntonioBerna]

🧠 Overview

The ModulinoKnob::get() method currently has a bug where it properly returns 0 when the I2C read operation fails, but it fails to update the internal _pressed state variable. This means that subsequent calls to isPressed() will return whatever the last successfully read button state was, rather than indicating that the state is unknown/invalid.

✅ Expected behavior

When I2C communication fails, both the position value and the button state should be invalidated.

❌ Current behavior

If I2C communication fails, the position is reset to 0, but the button state remains at its last known valid value.

🎮 Reproduction

1. Successfully read a knob with button pressed (_pressed = true)
2. Disconnect the I2C bus or cause another communication failure
3. Call get() - returns 0 as expected
4. Call isPressed() - incorrectly returns true when it should acknowledge the failure

✅ Proposed solution

Update the get() method to reset _pressed to false when read fails:

int16_t get() {
  uint8_t buf[3];
  auto res = read(buf, 3);
  if (res == false) {
    _pressed = false;  // Reset pressed state on read failure
    return 0;
  }
  _pressed = (buf[2] != 0);
  int16_t ret = buf[0] | (buf[1] << 8);
  return ret;
}