System for interfacing with an external accessory in one of two interface ...

United States Patent [w]

Rubbmark et al.

US006012105A [ii] Patent Number: [45] Date of Patent:

6,012,105 Jan. 4, 2000

[54] SYSTEM FOR INTERFACING WITH AN

EXTERNAL ACCESSORY IN ONE OF TWO
INTERFACE MODES BASED ON WHETHER
COMMUNICATION CAN BE ESTABLISHED
WITH EXTERNAL ACCESSORY OR NOT

[75] Inventors: Jan Rubbmark, Malmo ; Jan Lind, Bjarred; Lars Engelin, Sodra, all ol Sweden

[73] Assignee: Telefonaktiebolaget L M Ericsson,

Stockholm, Sweden

[21] Appl. No.: 08/848,910 [22] Filed: May 1, 1997

[51] Int. CI.7 G06F 13/00

[52] U.S. CI 710/14

[58] Field of Search 375/222; 710/105,

710/8, 73, 10, 14; 711/102

[56] References Cited

U.S. PATENT DOCUMENTS

4,654,655 3/1987 Kowalski 340/825.5

5,202,899 4/1993 Walsh 375/222

5,452,420 9/1995 Engdahl et al 710/105

5,598,577 1/1997 Overfield 710/10

5,634,074 5/1997 Devon et al 710/8

5,664,231 9/1997 Postman et al 710/73

5,802,550 9/1998 Fullam et al 711/102

FOREIGN PATENT DOCUMENTS

0 655 873 5/1995 European Pat. Off. .

OTHER PUBLICATIONS

IBM TDB, "Remote Modem—Type Sell-Learning", Nov. 1985, pp. 2398-2399.

The I2C-bus Benefits Designers and Manulacturers, Phillips Semiconductors, Apr. 1995.

"Accessory Detection by Oscillation", Motorola Technical
Developments, vol. 28, Aug. 1996, pp. 86-88.

Primary Examiner—Albert De Cady
Assistant Examiner—David Ton

Attorney, Agent, or Firm—Burns, Doane, Swecker &
Mathis, L.L.P.

[57] ABSTRACT

An electronic device operates with an external accessory by initiating a serial data communication over an accessory control bus. II data communication is established with the external accessory, the electronic device operates in a first interlace mode, when one or more operating parameters are translerred over the bus. II data communication is not established, the electronic device operates in a second interlace mode, when no operating parameters are translerred over the bus.

24 Claims, 3 Drawing Sheets