Method and Apparatus to Use Audio Port to Provide Power and Data Communications for Peripheral Devices

1. A computer-implemented method, comprising: activating a first application at a host device that requires a service from a peripheral device, wherein the first application drives a first audio signal into a first stereo output channel of an audio interface circuit of the host device and drives a second audio signal into a second stereo output channel of the audio interface circuit, and wherein the first audio signal and the second audio signal are complementary signals; harvesting energy by a power harvest module of the peripheral device from both the first audio signal and the second audio signal to generate a direct current (DC) voltage to power up one or more hardware components of the peripheral device including a microcontroller of the peripheral device; powering up and completing an initializing process at the peripheral device, wherein the microcontroller on the peripheral device generates peripheral device ready data, modulates the peripheral device ready data to a third signal, and transmits the third signal to an input channel of the audio interface circuit of the host device; confirming by the first application of the host device readiness of the peripheral device by receiving the third signal from the input channel of the audio interface circuit of the host device and demodulating the peripheral device ready data sent from the third signal received from the peripheral device; establishing by the first application of the host device duplex data communication with the peripheral device, by transferring data through the first and the second audio output channels of the audio interface circuit, and receiving data from the input channel of the audio interface circuit; and continuously receiving power by the peripheral device by harvesting energy from the first and the second audio channels of the audio interface circuit of the host device, while demodulating the data from the first and the second audio channels, wherein the peripheral device receives data sent from the host device, and wherein the peripheral device modulates data received from a second application on the peripheral device, and transmits the data to the host device via the audio input channel of the audio interface circuit of the host device.

2. The method of claim 1 , wherein the audio interface circuit of the host device includes a first stereo output channel, a second stereo output channel, an audio input channel, and a ground pin.

3. The method of claim 2 , wherein the first stereo output channel is a left stereo output channel, and wherein the second stereo output channel is a right stereo output channel.

4. The method of claim 1 , wherein harvesting energy from both the first audio signal and the second audio signal comprises rectifying the first and the second audio signals as differential alternating current (AC) signals into a DC voltage to generate the DC power.

5. The method of claim 1 , wherein peripheral device is configured to performing the following operations: detecting a fourth signal that has been modulated onto the first audio signal and the second audio signal; extracting the fourth signal from the first audio signal and the second audio signal; and processing the extracted fourth signal as part of data communicated from the host device to the peripheral device, including delivering the extracted data to the second application running within the peripheral device as an intended recipient.

6. The method of claim 5 , wherein detecting and extracting the fourth signal comprise: recognizing a first portion of the fourth signal that has been modulated in a first predetermined frequency; translating the first portion into a first binary data value; recognizing a second portion of the fourth signal that has been modulated in a second predetermined frequency; and translating the second portion into a second binary data value.

7. The method of claim 6 , wherein recognizing a first portion of the fourth signal comprises counting a number of consecutive pulses of the first predetermined frequency that is above a first predetermined threshold.

8. The method of claim 7 , wherein recognizing a second portion of the fourth signal comprises counting a number of consecutive pulses of the second predetermined frequency that is above a second predetermined threshold.

9. A peripheral device, comprising: a microcontroller; an interface circuit capable of communicatively coupling to a host device via an audio interface of the host device, the audio interface having a first stereo output channel, a second stereo output channel, an audio input channel, and a ground pin, wherein the interface circuit is to receive from the host device a first audio signal via the first stereo output channel and a second audio signal via the second stereo output channel; an energy harvesting circuit coupled to the interface circuit to harvest energy from both the first audio signal and the second audio signal to generate a direct current (DC) voltage to power up the peripheral device; and a program executed by the microcontroller to receive the first audio signal and the second audio signal from the interface circuit and to demodulate data from the first and the second audio signals, wherein the data is transmitted from an application running within the host device.

10. The device of claim 9 , wherein the first stereo output channel is a left stereo output channel, and the second stereo output channel is a right stereo output channel.

11. The device of claim 10 , wherein the program is to receive data from application circuit and peripheral device status, modulate the data into a third audio signal, and transmit the third audio signal to the host device via the audio input channel of the audio interface.

12. The device of claim 11 , wherein the energy harvesting circuit is to rectify the first and the second audio signals as differential alternating current (AC) signals into a DC voltage to generate the DC power.

13. The device of claim 12 , wherein the first audio signal and the second audio signal are complementary signals.

14. The device of claim 10 , wherein the program is configured to detect a fourth signal that has been modulated onto the first and the second audio signals, extract the fourth signal from the first and the second audio signals, and process the extracted fourth signal as part of data communicated from the host device to the peripheral device, including delivering extracted data to an application as an intended recipient.

15. The device of claim 14 , wherein the microcontroller includes a comparator to convert complementary first audio signal and second audio signal to a binary signal.

16. The device of claim 15 , wherein the microcontroller is further configured to recognize a first portion of the fourth signal that has been modulated in a first predetermined frequency, translate the first portion into a first binary data value, recognize a second portion of the fourth signal that has been modulated in a second predetermined frequency, and translate the second portion into a second binary data value.

17. The device of claim 16 , wherein recognizing a first portion of the fourth signal comprises counting a number of consecutive pulses of the first predetermined frequency that is above a first predetermined threshold.

18. The device of claim 16 , wherein recognizing a second portion of the fourth signal comprises counting a number of consecutive pulses of the second predetermined frequency that is above a second predetermined threshold.

19. A computer-implemented method, comprising: receiving, at a peripheral device communicatively coupled to a host device via an audio interface of the host device, the audio interface having a first stereo output channel, a second stereo output channel, an audio input channel, and a ground pin, a first audio signal via the first stereo output channel and a second audio signal via the second stereo output channel; harvesting energy from both the first audio signal and the second audio signal to generate direct current (DC) power to power one or more hardware components of the peripheral device including a processor of the peripheral device; and receiving data from the first stereo output channel and the second stereo output channel by demodulating data which has been modulated on the first and the second audio signals transmitted via the first and the second stereo output channels by host device, wherein the modulated data on the first and the second stereo output channels are complementary signals.

20. The method of claim 19 , wherein the first stereo output channel is a left stereo output channel, and wherein the second stereo output channel is a right stereo output channel.

21. The method of claim 19 , further comprising: receiving data from an application running within the peripheral device; modulating the data into a third audio signal; and transmitting the third audio signal with the modulated data from the peripheral device to the host device via the audio input channel of the audio interface.

22. The method of claim 19 , wherein harvesting energy from both the first audio signal and the second audio signal comprises rectifying the first and the second audio signals as differential alternating current (AC) signals into a DC Voltage to generate the DC power.