Ghosting or crosstalk in my matrix keypad or display?

Question

I'm experiencing ghosting or unexpected behavior when pressing keys on a matrix keypad, and I've also noticed similar issues in LED matrix displays. What typically causes ghosting or crosstalk in such matrix-based systems?

Is it related to missing diodes, poor scanning logic, or electrical interference? How can I fix or prevent it?

Divyam · Answer

Ghosting in keypads and LED matrices is usually caused by missing diodes and incorrect scanning logic, not just electrical interference. For keypads, always add isolation diodes if you expect multiple simultaneous keypresses. For LED matrices, ensure you scan the display correctly and fast enough.

In both cases, keep wiring tidy, and avoid crosstalk by separating signal lines. These steps will eliminate most ghosting and unintended behavior in matrix systems.