ISDN interface unit

• US 5,638,373 A
• Filed: 03/10/1995
• Issued: 06/10/1997
• Est. Priority Date: 11/29/1990
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Okuyama, Satoshi, Matsukura, Ryuichi, Takebayashi, Tomoyoshi, Hasegawa, Hiroki, Azami, Toshihiro
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US08/402,204
• Time in Patent Office: 823 Days
• Field of Search: 375/219, 375/242, 375/249, 341/75, 379/93, 379/97, 379/165, 370/68.1, 370/99, 370/110.1
• US Class Current: 370/467
• CPC Class Codes: H04Q 11/0471 Terminal access circuits
• CPC Class Codes: H04Q 2213/093 Personal computer
• CPC Class Codes: H04Q 2213/103 Memories
• CPC Class Codes: H04Q 2213/13031 Pulse code modulation, PCM
• CPC Class Codes: H04Q 2213/13034 A/D conversion, code compression/expansion
• CPC Class Codes: H04Q 2213/1309 Apparatus individually associated with a subscriber line, line circuits
• CPC Class Codes: H04Q 2213/13093 Personal computer, PC
• CPC Class Codes: H04Q 2213/13103 Memory
• CPC Class Codes: H04Q 2213/13106 Microprocessor, CPU
• CPC Class Codes: H04Q 2213/13174 Data transmission, file transfer
• CPC Class Codes: H04Q 2213/13176 Common channel signaling, CCS7
• CPC Class Codes: H04Q 2213/13199 Modem, modulation
• CPC Class Codes: H04Q 2213/13202 Network termination [NT]
• CPC Class Codes: H04Q 2213/13209 ISDN
• CPC Class Codes: H04Q 2213/13214 Clock signals
• CPC Class Codes: H04Q 2213/1327 Release and resetting of connection
• CPC Class Codes: H04Q 2213/13271 Forced release
• CPC Class Codes: H04Q 2213/13292 Time division multiplexing, TDM
• CPC Class Codes: H04Q 2213/13297 Coupling different rates in TDM systems, data rate adaptation
• CPC Class Codes: H04Q 2213/13299 Bus
• CPC Class Codes: H04Q 2213/1332 : Logic circuits
• CPC Class Codes: H04Q 2213/13322 : Integrated circuits
• CPC Class Codes: H04Q 2213/1336 : Synchronisation
• CPC Class Codes: H04Q 2213/214 : Phase shifted impulses; Clock signals; Timing
• CPC Class Codes: H04Q 2213/292 : Time (de)multiplexing
• CPC Class Codes: H04Q 2213/32 : Logic elements
• CPC Class Codes: H04Q 2213/322 : Integrated circuit
• CPC Class Codes: H04Q 2213/36 : Synchronisation

Abstract

An ISDN interface unit interconnects a data processing unit, an ISDN, and an analog telephone and includes a DMA request signal generation circuit for generating a DMA request signal from an 8 kHz clock signal from an ISDN line. In accordance with the request signal, PCM coded data input from the ISDN line is transferred, using DMA, to a memory of the data processing unit or vice versa. Alternatively, the ISDN interface unit includes a code conversion circuit. Data stored in the data processing unit are converted to nonlinear PCM coded data and transmitted to the ISDN line or vice versa. Further, the ISDN interface unit includes communication functions for the digital signal and for the voice band signal, a control channel signal sent from the ISDN line is interpreted, and one of the communication functions can be selected.

Claims

1. An ISDN interface unit mounted on a data processing unit for interfacing between the data processing unit and an ISDN line, comprising:

a code conversion circuit converting a nonlinear PCM coded data used in the ISDN line to a linear PCM coded data used in the data processing unit, and converting linear PCM coded data used in the data processing unit to nonlinear PCM coded data used in the ISDN line;

a data buffer circuit, coupled to the code conversion circuit, storing linear PCM coded data, wherein;

the linear PCM coded data stored in the data buffer circuit is converted to nonlinear PCM coded data by the code conversion circuit and transmitted to the ISDN line, and

the nonlinear PCM coded data transmitted from the ISDN line to the data processing unit is converted to the linear PCM coded data and stored in the data buffer circuit of the data processing unit.

2. An ISDN interface unit as set forth in claim 1, further comprising:

an ISDN connection circuit executing a physical interface in the connection to the ISDN line, wherein when a digital signal from the ISDN line is received, the digital signal is separated to obtain a 64 kbps information channel signal that is one of a control channel signal, a voice signal and data information; and

an ISDN connection control circuit extracting and interpreting an ISDN connection control message from separated control channel signal.

3. An ISDN interface unit as set forth in claim 2, further comprising:

a personal computer interface circuit executing an interface between the data processing unit and the ISDN interface unit.

4. An ISDN interface unit mounted on a data processing unit for interfacing between the data processing unit and an ISDN line, comprising:

a code conversion circuit converting a nonlinear PCM coded data used in the ISDN line to a linear PCM coded data used in the data processing unit, and converting linear PCM coded data used in the data processing unit to nonlinear PCM coded data used in the ISDN line; and

an addition circuit adding a voice signal output to the ISDN line or nonlinear PCM coded data of a voice signal input from the ISDN line and nonlinear PCM coded data output from the code conversion circuit,

the voice signal being combined with stored linear PCM coded data in the data processing unit in accordance with the addition process of the addition circuit, the combined data being output to the ISDN line or an analog telephone.

5. An ISDN interface unit as set forth in claim 4 further comprising:

an ISDN connection circuit executing a physical interface in connection with the ISDN line, separating a digital signal when the digital signal from the ISDN line is received, and obtaining a control channel signal for connection to the ISDN and a 64 kbps information channel signal being one of a voice signal and data information;

an ISDN connection control circuit extracting and interpreting an ISDN connection control message from the separated channel signal;

a personal computer interface circuit executing an interface between the data processing unit and the ISDN interface unit; and

a telephone interface circuit processing an interface for a connected analog telephone.