Apparatus for identifying accessories connected to radiotelephone equipment

• US 5,783,926 A
• Filed: 11/05/1996
• Issued: 07/21/1998
• Est. Priority Date: 11/05/1996
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Agnor, William C., Moon, Billy Gayle
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US08/744,102
• Time in Patent Office: 623 Days
• Field of Search: 320/2, 320/5, 320/6, 320/15, 320/30, 320/48, 320/106, 320/110, 320/116, 320/134, 320/136, 320/DIG. 18, 429/90, 429/149
• US Class Current: 320/106
• CPC Class Codes: H02J 7/00038 using passive battery identification means, e.g. resistors or capacitors identification by mechanical connections H02J7/0045
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H04M 1/6041 Portable telephones adapted for handsfree use

Abstract

An apparatus for identifying the identity of an accessory device connected to an electronic device using a voltage divider circuit, an analog to digital converter, and a database associating various digital values with the identity of various accessory devices. The voltage divider circuit includes a first resistor located within the electronic device and having a single resistance value. The voltage divider circuit also includes a second resistor located within the accessory device whose resistance value varies between accessories such that a distinct voltage value is applied to the analog to digital converter for each accessory. The digital output value of the analog to digital converter is compared with a list of values stored within the database to determine the identity of the accessory device.

Claims

1. An apparatus for identifying an accessory device connected to an electronic device from among a plurality of accessory devices, the apparatus comprising:

a constant current source for supplying a constant current;

a resistor of resistance distinct to each particular accessory in the plurality of accessory devices, the resistor having a first lead electrically connected to the constant current source, and the resistor further having a second lead electrically connected to electrical ground;

an analog to digital converter having an analog input electrically connected to the first lead of the resistor, the analog to digital converter for measuring the voltage level across the resistor, and the analog to digital converter further for creating a digital representation of the measured voltage level and communicating the digital representation of the measured voltage level to the electronic device; and

a database accessible by the electronic device for associating the digital representation of the measured voltage level with the identity of the accessory device connected to the electronic device.

2. An apparatus for identifying an accessory connected to an electronic device from among a plurality of accessory devices, the apparatus comprising:

a constant current source located within the electronic device connected to a first interface terminal of the electronic device;

a resistor of resistance value distinct to each particular accessory in the plurality of accessory devices, the resistor located within the accessory device, the resistor having a first lead electrically connected to a first interface terminal of the accessory device, and the resistor further having a second lead electrically connected to a second interface terminal of the accessory device, and the second lead further is electrically connected to electrical ground of the accessory device;

an analog to digital converter located within the electronic device, the analog to digital converter having an analog input electrically connected to the first interface terminal of the electronic device, the analog to digital converter further having a ground terminal connected to electrical ground of the electronic device, the analog to digital converter for measuring the voltage level on the first interface terminal of the electronic device and converting the measured voltage level to a digital binary word and further for communicating the digital binary word to the electronic device;

an interface for connecting the first interface terminal of the electronic device to the first interface terminal of the accessory device and for connecting the second interface terminal of the electronic device to the second interface terminal of the accessory device; and

a database accessible by the electronic device for associating the digital binary word with the identity of the accessory device connected to the electronic device.

3. An method for identifying an accessory connected to an electronic device from among a plurality of accessory devices, the apparatus comprising the steps of:

assigning each accessory device a distinct resistance value;

connecting a constant current source to a first lead of a resistor, a resistor having the assigned resistance value for the accessory connected to the electronic device;

connecting a second lead of the resistor to ground to form a current path from the constant current source through the resistor to ground;

measuring a voltage value across the second resistor;

associating each accessory device identity with the distinct voltage value created across the resistor as electrical current flows from the constant current source through the resistor of resistance value assigned to the particular accessory device to ground; and

determining the accessory device identity through association with the measured voltage value.