Self-test for receive and transmit hardware functional safety associated with a touch panel or screen

A system comprising:

• a sinusoidal signal generator that generates, over a signal bus, a sinusoidal drive signal;
• a touch panel comprising a plurality of electrodes to be excited by the sinusoidal drive signal;
• receive (RX) sensing hardware coupled to an electrode of the plurality of electrodes, wherein the RX sensing hardware comprises:
• an attenuator configured to detect a touch signal from the electrode;
• a multiplexer coupled between an input to the attenuator and the signal bus;
• and
• a capacitor coupled between the signal bus and the multiplexer;
• and
• control logic coupled to the RX sensing hardware, the control logic to perform a self-test comprising to:
• disconnect the RX sensing hardware from the electrode;
• cause the multiplexer to couple the capacitor to the input of the attenuator;
• and
• generate a fault alert, via the touch panel, in response to an output of the RX sensing hardware not being within a functional operating range.

A method of performing a self-test for an device comprising a signal bus that carries a sinusoidal drive signal and receive (RX) sensing hardware, coupled to an electrode of a touch panel, including an attenuator configured to detect a touch signal from the electrode, a multiplexer coupled between an input to the attenuator and the signal bus, and a capacitor coupled between the signal bus and the multiplexer, wherein the method of performing the self-test comprises:

• causing the RX sensing hardware to be disconnected from the electrode;
• causing the multiplexer to couple the capacitor to the input of the attenuator;
• and
• determining whether an output of the RX sensing hardware is within a functional operating range.