Digital microphone interface, audio codec and methods for use therewith

• US 7,856,283 B2
• Filed: 01/31/2006
• Issued: 12/21/2010
• Est. Priority Date: 12/13/2005
• Status: Expired due to Fees

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: SigmaTel Incorporated (NXP Semiconductors NV)
• Inventors: Burk, Theodore, Bogard, Daniel T.
• Primary Examiner(s): Ni; Suhan
• Assistant Examiner(s): Elbin; Jesse A
• Application Number:
  US11/344,274
• Publication Number:
  US 20070133826A1
• Time in Patent Office: 1,785 Days
• Field of Search: 381/111, 381/122, 381/91, 381/92, 381/97, 710/58, 710/61, 370/478, 370/498, 370/516, 370/518, 370/530, 370/536, 375/362, 375/373
• US Class Current: 700/94
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A digital microphone interface includes a phase generator for generating a phase signal. A clock generator produces a digital microphone clock at a selected frequency based on the frequency select signal, and supplying the digital microphone clock to a digital microphone. A first data latch, operably coupled to the phase generator, produces a stream of first data from a first channel of the digital microphone, based on a phase select signal and the phase signal.

Claims

1. A digital microphone interface comprising:

a phase generator, operably coupled to a system clock and a frequency select signal for generating a phase signal;

a clock generator, operably coupled to a system clock signal and the phase generator, for producing a digital microphone clock at a selected frequency based on the frequency select signal, and for supplying the digital microphone clock to a digital microphone; and

a first data latch, operably coupled to the phase generator, for producing a stream of first data from a first channel of the digital microphone, based on a phase select signal and the phase signal.

2. The digital microphone interface of claim 1 wherein the first phase select signal includes a first latch phase and wherein the first data latch latches the first data stream when the phase signal is equal to the first latch phase.

3. The digital microphone interface of claim 1 further comprising:

a second data latch, operably coupled to the counter, for producing a stream of second data from a second channel of the digital microphone, based on the phase select signal and the phase signal.

4. The digital microphone interface of claim 3 further comprising:

a channel combiner, for combining the first stream of data and the second stream of data into a combined data stream.

5. The digital microphone interface of claim 4 wherein the channel combiner is operably coupled to a mode select signal, and wherein the channel combiner combines the first stream of data and the second stream of data into the combined data stream, when the mode select signal indicates a monaural mode.

6. The digital microphone interface of claim 1 wherein the first data latch is operably coupled to a mode select signal, and wherein the first data latch is disabled if the first channel is not selected.

7. The digital microphone interface of claim 1 wherein the first data latch is operably coupled to a mode select signal, and wherein the first data latch latches the stream of first data at one phase value of the phase signal when the mode select indicates a monaural mode.

8. The digital microphone interface of claim 1 wherein the first data latch is operably coupled to mode select signal, and wherein the first data latch latches the stream of first data at two phase values of the phase signal when the mode select indicates a stereo mode.

9. The digital microphone interface of claim 1 wherein the phase select signal includes one of:

a rising edge phase, a midpoint high phase, a falling edge phase, and a midpoint low phase.

10. An audio codec comprising:

a phase generator, operably coupled to a system clock and a frequency select signal for generating a phase signal;

a clock generator, operably coupled to a system clock signal and the phase generator, for producing a digital microphone clock at a selected frequency based on the frequency select signal, and for supplying the digital microphone clock to a digital microphone;

a first data latch, operably coupled to the phase generator, for producing a stream of first data from a first channel of the digital microphone, based on a phase select signal and the phase signal;

a decimation and filter module, operably coupled to the stream of first data, for producing a down sampled signal; and

a data formatter, operably coupled to the down sampled signal, for producing a formatted digital audio signal.

11. The audio codec of claim 10 wherein the first phase select signal includes a first latch phase and wherein the first data latch latches the first data stream when the phase signal is equal to the first latch phase.

12. The audio codec of claim 10 further comprising:

a second data latch, operably coupled to the counter, for producing a stream of second data from a second channel of the digital microphone, based on the phase select signal and the phase signal.

13. The audio codec of claim 12 further comprising:

a channel combiner, for combining the first stream of data and the second stream of data into a combined data stream;

wherein the decimation and filter module produces the down sampled signal based on the combined data stream.

14. The audio codec of claim 13 wherein the channel combiner is operably coupled to a mode select signal, and wherein the channel combiner combines the first stream of data and the second stream of data into the combined data stream, when the mode select signal indicates a monaural mode.

15. The audio codec of claim 10 wherein the first data latch is operably coupled to a mode select signal, and wherein the first data latch is disabled if the first channel is not selected.

16. The audio codec of claim 10 wherein the first data latch is operably coupled to a mode select signal, and wherein the first data latch latches the stream of first data at one phase value of the phase signal when the mode select indicates a monaural mode.

17. The audio codec of claim 10 wherein the first data latch is operably coupled to mode select signal, and wherein the first data latch latches the stream of first data at two phase values of the phase signal when the mode select indicates a stereo mode.

18. The audio codec of claim 10 wherein the phase select signal includes one of:

a rising edge phase, a midpoint high phase, a falling edge phase, and a midpoint low phase.

19. A method comprising:

generating a phase signal based on a system clock and a frequency select signal;

producing a digital microphone clock at a selected frequency based on the frequency select signal;

supplying the digital microphone clock to a digital microphone;

producing a stream of first data from a first channel of the digital microphone, based on a phase select signal and the phase signal.

20. The method of claim 19 wherein the first phase select signal includes a first latch phase and wherein the step of producing a stream of first data includes latching the first data stream when the phase signal is equal to the first latch phase.

21. The method of claim 19 further comprising:

producing a stream of second data from a second channel of the digital microphone, based on the phase select signal and the phase signal.

22. The method of claim 21 further comprising:

combining the first stream of data and the second stream of data into a combined data stream.

23. The method of claim 22 wherein the channel combiner combines the first stream of data and the second stream of data into the combined data stream, when a mode select signal indicates a monaural mode.

24. The method of claim 19 wherein the step of producing a stream of first data includes latching the stream of first data at one phase value of the phase signal when a mode select indicates a monaural mode.

25. The method of claim 19 wherein the step of producing a stream of first data includes latching the stream of first data at two phase value of the phase signal when a mode select indicates a stereo mode.

26. The method of claim 19 wherein the phase select signal includes one of:

a rising edge phase, a midpoint high phase, a falling edge phase, and a midpoint low phase.