Abstract: This application discusses among other things, apparatus and method for transmitting data with an analog signal without significantly distorting the analog signal. In an example, an apparatus can include an audio channel, a capacitor coupled to a first conductor of the audio channel, the capacitor configured to couple an analog representation of a digital data signal with an analog audio signal on the audio channel, and a frequency modulator configured to receive the digital data signal and to modulate a frequency of an output signal of the frequency modulator based on a logic level of the digital data signal, wherein the analog representation of the digital data signal includes the frequency of the output signal of the frequency modulator.

Abstract: This application discusses among other things, apparatus and method for transmitting data with an analog signal without significantly distorting the analog signal. In an example, an apparatus can include an audio channel, a capacitor coupled to a first conductor of the audio channel, the capacitor configured to couple an analog representation of a digital data signal with an analog audio signal on the audio channel, and a frequency modulator configured to receive the digital data signal and to modulate a frequency of an output signal of the frequency modulator based on a logic level of the digital data signal, wherein the analog representation of the digital data signal includes the frequency of the output signal of the frequency modulator.

Abstract: This document discusses, among other things, methods and apparatus for detecting an attached state of a port of a device. In an example, a method can include monitoring a supply bus pin of a USB port for a valid voltage using a first state machine, monitoring an ID pin of the USB port for a non-floating voltage using a second state machine, and simultaneously and independently executing the first state machine and the second state machine, wherein the first state machine is different than the second state machine.

Abstract: This document discusses, among other things, a multiple accessory detection apparatus and methods for identifying accessories coupled to a multi-pin connector of an electronic device. The apparatus can include a first reference generator, a second reference generator, a plurality of switches to couple an output of the second generator to an accessory device and a comparator. The comparator can generate identifying information about the accessory device using the reference information received from the first reference generator and test information received using the second reference generator.

Abstract: This document discusses, among other things, a multiple accessory detection apparatus and methods for identifying accessories coupled to a multi-pin connector of an electronic device. The apparatus can include a first reference generator, a second reference generator, a plurality of switches to couple an output of the second generator to an accessory device and a comparator. The comparator can generate identifying information about the accessory device using the reference information received from the first reference generator and test information received using the second reference generator.