Input/output multiplexer bus
AssigneeCypress Semiconductor Corporation
InventorDennis R. Seguine
Life of this patent
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Abstract
One embodiment includes and I/O bus including a signal line coupled to a signal source and multiple line switches, each line switch to couple a corresponding I/O port to the signal line. Switch logic coupled to the I/O bus may programmatically switch the multiple line switches to couple at least one of the signal source and measurement circuitry to the respective I/O port.
Claims22
A capacitance measurement circuit comprising:
- a plurality of capacitance measurement electrodes;
- a multiplexor bus coupled to the plurality of capacitance measurement electrodes;
- a first capacitance measurement circuit coupled to the multiplexor bus;
- a second capacitance measurement circuit coupled to the multiplexor bus;
- and
- a summing capacitor coupled to the multiplexor bus.
A method comprising:
- coupling a capacitance measurement electrode to a multiplexor bus;
- coupling a first capacitance measurement circuit to the multiplexor bus;
- converting a capacitance of the capacitance measurement electrode to a first digital value;
- coupling a second capacitance measurement circuit to the multiplexor bus;
- converting the capacitance of the capacitance measurement electrode to a second digital value;
- and
- detecting a presence of a conductive object on the capacitance measurement electrode based on the first and second digital values.
A measurement system comprising:
- a plurality of input/outputs (I/Os);
- a multiplexor bus coupled to the plurality of I/Os;
- a first capacitance measurement circuit coupled to the multiplexor bus;
- a second capacitance measurement circuit coupled to the multiplexor bus;
- a summing capacitor coupled to the multiplexor bus;
- and
- a processing circuit coupled to the first and second capacitance measurement circuits.
The measurement system of clam 17, wherein the first capacitance measurement circuit and the second capacitance measurement circuit are substantially identical.
Dependencies are inferred from the claim text.