IP packet ready PBX expansion circuit for a conventional personal computer with expandable, distributed DSP architecture

• US 20050030941A1
• Filed: 09/01/2004
• Published: 02/10/2005
• Est. Priority Date: 03/02/2000
• Status: Active Grant

• Current Assignee: Charles Arnold Lasswell, Gregory J. Schultz, Paul K. Lee
• Original Assignee: Charles Arnold Lasswell, Gregory J. Schultz, Paul K. Lee
• Inventors: Lee, Paul K., Lasswell, Charles Arnold, Schultz, Gregory J.
• Granted Patent: US 7,529,253 B2
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04M 3/42314 in private branch exchanges
• CPC Class Codes: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42

Abstract

A personal computer includes a PBX control program and one or more switch cards located in expansion board slots. The one or more switch cards are coupled to one or more port expansion units (PEU), which are coupled to telecommunication lines out to the various extension phones at the customer premises. Each PEU contains its own digital signal processor (DSP) so that distributed digital signal processing may be implemented to avoid any bottlenecks. One master PEU is coupled to a switch card by a time division multiplexed (TDMA) bus as well as a packet switched control bus, and all the other PEUs, if any, are coupled to the master PEU by extensions of the TDMA and packet switched buses. The TDMA bus carries PBX real time conversations while the packet switched bus carries control information, voicemail outbound message data packets, and inbound voicemail data packets.

Claims

1. An apparatus, comprising:

a personal computer having a plurality of expansion slots;

one or more switch card circuits coupled to said expansion slots, each including a switching integrated circuit capable of coupling data in at least one timeslot to at least one other timeslot on a time division multiplexed bus and further comprising an interface circuit for a time division multiplexed bus and a packet switched bus; and

one or more port expansion units coupled together in a daisy chain by a time division multiplexed bus and a packet switched bus, each said daisy chain of port expansion units having a port expansion unit in the chain coupled to a switch card via a time division multiplexed bus and a packet switched bus which are extensions of the packet switched and time division multiplexed buses which couple each daisy chain together and also having a bus interface circuit for said buses, each said port expansion unit including one or more port interface circuits for interfacing the port expansion unit to a telecommunication line, one or more digital signal processors coupled between said bus interface circuit and said port interface circuits, and one or more microcontrollers coupled between said bus interface circuit and said one or more digital signal processors,

wherein said personal computer includes a private branch exchange (PBX) program, which when executed causes said personal computer to implement a PBX process to communicate with said one or more microcontrollers via port interface circuits on each said port expansion unit to determine call progress and port status, to send data to said microcontrollers to control signaling functions implemented by said port interface circuits, and to control switching of said switch cards to implement at least some conventional PBX functionality.

2. The apparatus of claim 1, wherein said microcontrollers in each said port expansion unit are programmed to read status signals from said port interface circuits, to receive commands from said PBX process, to send commands to said port interface circuits to implement signaling functions, and to send write tone data to a digital signal processor in said port expansion unit to cause tone generation on channels designated in data received from said PBX program for signaling purposes.

3. The apparatus of claim 2, wherein said one or more digital signal processors in said port expansion unit are programmed to receive data from said time division multiplexed bus for channels corresponding to PBX connections and said tone data, and to implement a volume control weighting function to mix said channel data and said tone data to form resulting data, and to send the resulting data to the appropriate port interface circuit for transmission to a central office.

4. The apparatus of claim 2, where said one or more digital signal processors are programmed to receive data from port interface circuits, to place said data onto predetermined channels of said time division multiplexed bus, to receive data from said port interface circuits representing each incoming signaling tone, and to decode said data to determine which tone has been received to interrupt said microcontroller for each said tone received.

5. The apparatus of claim 4, said one or more microcontrollers being programmed to respond to each interrupt from said one or more digital signal processors, to determine the tone which has been received, and to send a message to said PBX process identifying the tone which has been received.

6. The apparatus of claim 1, said personal computer including programming, which when executed as part of a telephony process including voice mail, to send data representing voice mail messages to the appropriate one or more ports via packets on said packet switched bus, wherein the microcontrollers that receive said packets are programmed to strip out the payload data of each said packet and write a resulting packet into a packet data buffer accessible by said one or more digital signal processors.

7. The apparatus of claim 6, wherein said one or more digital signal processors are programmed to mix said packet data in with tone data and said channel data in a volume control weighting process to generate combined data and to send the combined data out to the appropriate one or more said ports for transmission to a central office.

8. The apparatus of claim 1, wherein said one or more digital signal processors are programmed to receive data to be recorded as a voicemail message, to save said data into a record buffer, to interrupt at least one of said one or more microcontrollers, the one or more microcontrollers in said port expansion unit to receiving said interrupt, to retrieve said voicemail data from said record buffer, to packetize said voicemail data, and to transmit, via said packet switched bus, said packetized voicemail data to a telephony process on said personal computer.

9. The apparatus of claim 8, said personal computer including programming, which when executed as part of a telephony process including voice mail, causes the personal computer to receive said packetized voicemail data including voicemail messages to be recorded from one or more of the port expansion interface units.

10. A method of operating a PBX system on a personal computer, comprising:

loading code for one or more digital signal processors (DSPs), and programming a field programmable gate array (FPGA) by a microcontroller (MC);

initializing, by said one or more DSPs, each function and waiting for channel assignments by said MC;

learning an address of the FPGA by watching a match bit of a token;

interrupting, by the FPGA, the MC after the address has been learned, and setting an operational flag,

transmitting a packet to a PBX program on a host computer to indicate a port expansion unit (PEU) including the MC, the one or more DSPs, and the FPGA is operational;

transmitting a predefined packet to said PBX program indicating how many ports the PEU includes;

receiving a response back from said PBX program with an assignment of a channel on a bus for each port on the PEU;

distributing, by the microcontroller, of the assigned channels among the one or more DSPs; and

transmitting to the one or more DSPs a start processing signal.

11. The method of claim 10, further including the one or more DSPs buffering first timeslot data for a plurality of timeslots from a bus that is to be transmitted to said ports of the PEU and buffering second timeslot data for a plurality of timeslots of incoming data from said ports of the PEU.

12. The method of claim 11, further including the one or more DSPs receiving and buffering in one or more tone buffers tone data received from the MC.

13. The method of claim 12, further including the one or more DSPs receiving payloads of voice data from prerecorded messages and voicemail packets which were transmitted over a packet bus.

14. The method of claim 13, further including the one or more DSPs reading the first timeslot data, the second timeslot data, the tone data, and the voice data and weighing data according to a volume control weighting function and summing the results to created resulting volume control mixed data.

15. The method of claim 14, further including the one or more DSPs writing the resulting volume control mixed data to an appropriate buffer.

16. The method of claim 11, wherein the microcontroller receives a host packet from the PBX program identifying dial tone multi-frequency (DTMF) tones to generate for each channel.

17. The method of claim 16, said microcontroller retrieving pulse-code modulated (PCM) data for the identified DTMF tones and writing the PCM data into the one or more tone buffers corresponding to each channel.

18. The method of claim 17, said one or more DSPs performing volume control weighting on the PCM data in the one or more tone buffers, summing the volume control weighted data, and writing the summed volume control weighting data into an output buffer corresponding to each said channel.