FIFO and system synchronization system and method

• US 6,075,831 A
• Filed: 09/04/1997
• Issued: 06/13/2000
• Est. Priority Date: 12/29/1995
• Status: Expired due to Term

• Current Assignee: Microsemi Semiconductor (U.S.) Inc. (Microchip Technology Incorporated)
• Original Assignee: Advanced Micro Devices SDN Berhad (Advanced Micro Devices, Inc.)
• Inventors: Hendrickson, Alan, Schnizlein, Paul
• Primary Examiner(s): Nguyen, Viet Q.
• Application Number:
  US08/923,321
• Time in Patent Office: 1,013 Days
• Field of Search: 365/221, 377/28, 377/33, 380/48, 370/195.1, 370/20.1, 379/61, 375/359, 375/355, 375/360, 375/363, 375/365, 375/370, 375/372, 375/376
• US Class Current: 375/359
• CPC Class Codes: H04J 3/062 Synchronisation of signals having the same nominal but fluctuating bit rates, e.g. using buffers pulse-stuffing H04J3/07; asynchronous-synchronous conversion H04L5/24; speed conversion H04L25/05; speed conversion in computers G06F5/06
• CPC Class Codes: H04L 2007/045 Fill bit or bits, idle words
• CPC Class Codes: H04M 1/72502 with one base station connected to a single line

Abstract

A method for handling underflow and overflow of data in a FIFO buffer includes steps of inserting an insert data word in the FIFO buffer if there is an underflow of data at the FIFO buffer and discarding a discard data word of the FIFO buffer if there is an overflow of data at the FIFO buffer. In one embodiment, the insert data word is null and does not change the status of the FIFO buffer.

Claims

1. A method for providing data words for use within a digital cordless telephone, comprising the steps of:

receiving an input series of data words into an input of a buffer;

transmitting an output series of data words from an output of the buffer;

inserting an insert data word into the output series if there is an underflow of data at the buffer; and

discarding a discard data word from the input series if there is an overflow of data at the buffer.

2. The method of claim 1, wherein the insert data word is null and does not change status of the buffer.

3. The method of claim 1, wherein the the insert data word is inserted at the output of the buffer.

4. The method of claim 1, wherein the insert data word is defined by a series of zeros.

5. The method of claim 1 wherein the buffer is a first-in-first-out (FIFO) buffer, and wherein the digital cordless telephone includes a codec in the handset to use the output series of data words.

6. The method of claim 5 wherein the FIFO buffer forms a portion of a digital cordless telephone handset unit.

7. The method of claim 5 wherein the FIFO buffer forms a portion of a digital cordless telephone base set unit.

8. A method for handling underflow of data in a buffer, within a digital cordless telephone, the telephone using a coding scheme having an invalid code word, comprising the steps of:

determining whether there is an underflow of data at the buffer; and

upon a determination that there is an underflow, inserting an insert data word at an output of the buffer.

9. The method of claim 8, wherein the insert word is a null word.

10. The method of claim 8, wherein the telephone has a predetermined timing and the inserted data word allows the telephone to maintain the predetermined timing.

11. The method of claim 8 for also handling overflow of data in the buffer, comprising the steps of:

determining whether there is an overflow of data at the buffer; and

upon a determination that there is an overflow, discarding a discard data word from an input of the buffer.

12. The method of claim 8 wherein the buffer is a first-in-first-out (FIFO) buffer.

13. The method of claim 12 wherein the FIFO buffer is a portion of a digital cordless telephone handset unit.

14. The method of claim 12 wherein the FIFO buffer is a portion of a digital cordless telephone base set unit.

15. A system for receiving a flow of data for use by a digital cordless telephone, the system comprising:

a buffer for receiving the flow of data and transmitting an output flow of data for use by the digital cordless telephone;

means for determining whether there is an overflow of the received flow of data at the buffer; and

means, responsive to a determination that there is an overflow, for discarding a discard data word from the received flow of data at the buffer.

16. The system of claim 15, wherein the insert word is a null word.

17. The system of claim 15 further comprising:

means for determining whether there is an underflow of the output flow of data at the buffer; and

means, upon a determination that there is an underflow for providing an insert data word in the output flow of data.

18. The system of claim 15 wherein the buffer is a first-in-first-out (FIFO) buffer.

19. The system of claim 18 wherein the FIFO buffer forms a portion of a handset unit of the digital cordless telephone.

20. The system of claim 18 wherein the FIFO buffer forms a portion of a base set unit of the digital cordless telephone.

21. A method for providing data words for use within a digital telephone, comprising the steps of:

receiving an input series of data words into a buffer;

transmitting an output series of data words from the buffer;

inserting an insert data word into the output series if there is an underflow of data at the buffer; and

discarding a discard data word from the input series if there is an overflow of data at the buffer.