Auto-switching communication interface
A touch detection system in accordance with one embodiment of the invention can include a circuit for converting a capacitance to a digital value. The touch detection system can include first and second communication interface circuits for enabling a first and second communication protocols, respectively. Furthermore, the touch detection system can include a detector circuit coupled to the first communication interface circuit and the second communication interface circuit. The detector circuit can be for automatically detecting a factor that indicates automatically enabling the first communication interface circuit and automatically disabling the second communication interface circuit. The detector circuit can be for detecting a coupling of a pin of the first communication interface circuit that is not used by the second communication interface circuit.
1. A circuit comprising:
a first communication interface circuit for enabling a first communication protocol;
a second communication interface circuit for enabling a second communication protocol; and
a detector circuit coupled to the first communication interface circuit and the second communication interface circuit, the detector circuit for automatically detecting a factor that indicates automatically enabling the first communication interface circuit and automatically disabling the second communication interface circuit,
wherein the detector circuit is for detecting a coupling of an output pin of the first communication interface circuit to a fixed voltage source,
wherein the output pin of the first communication interface circuit is not used by the second communication interface circuit, and
wherein the fixed voltage source represents a logic 0 or logic 1.
2. The circuit of claim 1 further comprising capacitance measurement circuitry configured to convert a capacitance of at least one capacitance measurement electrode to a digital value, wherein the digital value is communicated to a host through the first or second communication interface circuits.
3. The circuit of claim 2 , wherein the at least one capacitance measurement electrode is one of a plurality of capacitance measurement electrodes in an array.
4. The circuit of claim 1 , wherein the first communication interface circuit comprises a Serial Peripheral Interface (SPI) bus slave interface.
5. The circuit of claim 1 , wherein the second communication interface circuit comprises an Inter-Integrated Circuit (I 2 C) bus slave interface.
6. The circuit of claim 1 , wherein the factor comprises a voltage difference.
7. The circuit of claim 1 , wherein the factor comprises a signal difference.
8. A touch sensing device comprising:
a measurement circuit configured to convert a capacitance on at least one capacitance measurement electrode to a digital value; and
a communication circuit comprising:
a first interface circuit for enabling a first communication protocol,
a second interface circuit for enabling a second communication protocol, and
a detector circuit coupled to the first interface circuit and the second interface circuit, the detector circuit for automatically detecting a factor that indicates automatically enabling the first interface circuit and automatically disabling the second interface circuit,
wherein the detector circuit is for detecting a coupling of an output pin of the first interface circuit to a fixed voltage source,
wherein the output pin of the first interface circuit is not used by the second interface circuit, and
wherein the fixed voltage source represents a logic 0 or logic 1.
9. The touch sensing device of claim 8 wherein the first interface circuit comprises a Serial Peripheral Interface (SPI) bus slave interface.
10. The touch sensing device of claim 9 , wherein the second communication interface circuit comprises an Inter-Integrated Circuit (I 2 C) bus slave interface.