Serial data interface

• US 20030223502A1
• Filed: 09/09/2002
• Published: 12/04/2003
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Microsemi Corporation (Microchip Technology Incorporated)
• Original Assignee: Microsemi Corporation (Microchip Technology Incorporated)
• Inventors: Madsen, Jesper Steensgaard, Chatterjee, Shouri, Lagervall, Per Arne
• Granted Patent: US 6,952,174 B2
• Time in Patent Office: Days
• US Class Current: 375/247
• CPC Class Codes: H04S 1/007 in which the audio signals are in digital form data reduction aspects thereof based on psychoacoustics G10L19/02

Abstract

A method of encoding a first stream of digital signal data words is provided. A most recent value of the first stream of digital signal data words is received and memorized. A previous value of the first stream of digital data words is received and memorized. The most recent and the previous values of the stream of digital data words are combined to create a second data stream. The words are converted in the second data stream into a serial representation. The serial representation is transmitted on a single wire interface.

Claims

1. An encoder, comprising:

an input adapted to receive a digital input data stream; and

a conversion circuit adapted to convert said digital input data stream into an output data stream composed of at least 2-bit codes, wherein said conversion circuit generates said codes as a function of transistions of said input data stream, wherein each bit of said codes have the same voltage level when said digital input data stream alternates between two predefined numeric values.

2. The encoder as specified in claim 1 wherein said conversion circuit provides said output data stream serially on a single conductor.

3. The encoder as specified in claim 1 wherein said output data stream is composed of codes having each 2 bits of resolution.

4. The encoder as specified in claim 1 wherein said digital input data stream is composed of values proportional to values chosen from the set of minus eight, minus one, plus one, and plus eight.

5. The encoder as specified in claim 1 wherein said codes are represented by 00, 01, 10 and 11.

6. The encoder as specified in claim 1 wherein said conversion circuit compares a previous value of said digital input data stream with a most recent value of said digital input data stream to generate said output data stream.

7. The encoder as specified in claim 1 wherein said conversion circuit provides said output data stream such that the polarity of said output data stream is ascertainable by a receiver.

8. The encoder as specified in claim 1 wherein a predetermined code is generated every time the input data stream comprises a predetermined numeric value.

9. The encoder as specified in claim 8 wherein said predetermined numeric value is a representative of the largest absolute value that can be represented by said input data stream.

10. The encoder as specified in claim 1 wherein said conversion circuit is a state machine.

11. The encoder as specified in claim 10 wherein said state machine starts at a predetermined state at initialization of said digital input serial data stream.

12. The encoder as specified in claim 11 wherein said conversion circuit synchronizes everytime said output data stream has a predetermined state.

13. The encoder as specified in claim 1 further comprising an ADC generating said input digital data stream.

14. The encoder as specified in claim 13 wherein said output data stream is provided at a rate substantially higher than twice the signal bandwidth of said ADC.

15. The encoder as specified in claim 14 wherein said ADC converter comprises a delta-sigma modulator.

16. The encoder as specified in claim 14 wherein said ADC is disposed with a hearing aid.

17. A method of encoding a first stream of digital signal data words, comprising the steps of:

receiving and storing a most recent value of said first stream of digital data words;

receiving and storing a previous value of said first stream of digital data words;

comparing said most recent value and said previous value of said stream of digital data words to create a second data stream having at least 2-bit words;

providing the words in said second data stream in a serial representation; and

transmitting said serial representation on a single wire interface.

18. The method of claim 17 further comprising the step of synchronizing a transmission of said serial representation with edges of a received clock signal.

19. The method of claim 17 wherein said second stream of digital data words is composed of two-bit digital data words.

20. The method of claim 17 wherein said first stream of digital data words is generated by analog-to-digital conversion of an audio signal.

21. The method of claim 20 wherein the analog-to-digital conversion of an audio signal comprises the step of using a delta-sigma modulator.

22. The method of claim 20 wherein said delta-sigma modulator is disposed inside a microphone.

23. The method of claim 17 wherein said microphone is disposed in a hearing aid.

24. A method of operating an encoder, comprising the steps of:

receiving a digital input serial data stream; and

converting said digital input serial data stream to at least a 2-bit code, wherein said code is generated as a function of a transition of said digital input serial data stream, and also as a function of a lack of a transition of said digital input serial data stream, wherein each bit of said code has the same voltage level when said digital input serial data stream transitions.

25. The method as specified in claim 24 wherein said conversion circuit provides said output data stream on a single conductor.

26. The method as specified in claim 24 wherein said conversion circuit compares a previous value of said digital input serial data stream with a most recent value of said digital input serial data stream to generate said output data stream.

27. The method as specified in claim 24 wherein said predetermined code is digital 11.

28. The method as specified in claim 24 wherein said predetermined code is digital 00.

29. The method as specified in claim 24 wherein said code is representative of a digital code 00, 01, 10 and 11.

30. The method as specified in claim 24 wherein said conversion circuit provides said output data stream such that a phase of said output data stream is ascertainable by a receiver.

31. The method as specified in claim 30 wherein said output data stream is set by the conversion circuit at a first predetermined code to establish synchronization at initialization of said digital input serial data stream.

32. The method as specified in claim 31 wherein a phase of said output data stream is ascertainable upon a reset event.

33. The method as specified in claim 24 wherein said conversion circuit is a state machine.

34. The method as specified in claim 33 wherein said state machine starts at a predetermined state at initialization of said digital input serial data stream.

35. The method interface as specified in claim 34 wherein said conversion circuit synchronizes everytime said output data stream has a predetermined state.

36. The method as specified in claim 24 wherein said output data stream comprises a sequence of codes at a rate substantially higher than the Nyguist rate.

37. The method as specified in claim 24 further comprising an ADC generating said input digital serial data stream.

38. The method as specified in claim 37 wherein said ADC converter comprises a delta-sigma modulator.

39. The method as specified in claim 24 further comprising a receiving circuit converting said output data stream to a serial data stream.

40. The method as specified in claim 24 wherein said digital input serial data stream is digitized signals from a microphone.

41. The method as specified in claim 40 wherein said microphone is disposed with a hearing aid.