MIC/GND DETECTION AND AUTOMATIC SWITCH
This document discusses, among other things, an audio jack detection switch configured to be coupled to first and second GND/MIC terminals of an audio jack, wherein the audio jack detection switch includes a detection circuit configured to measure an impedance on the first and second GND/MIC terminals and identify each GND/MIC terminal as either a GND pole or a MIC pole using the measured impedance, and wherein the audio jack detection switch includes a switch configured to automatically couple an identified MIC pole to a MIC connection and to automatically couple an identified GND pole to a GND connection using information from the detection circuit.
1 . A system comprising:
an audio jack detection switch configured to be coupled to a four-pole audio jack including:
a left speaker (LSPKR) pole;
a right speaker (RSPKR) pole;
a ground (GND) pole; and
a microphone (MIC) pole;
wherein the audio jack detection switch includes:
a detection circuit configured to measure an impedance on at least one pole of the four-pole audio jack and to identify the GND pole and the MIC pole using the measured impedance; and
a switch configured to automatically couple the identified MIC pole to a MIC connection of a processor and to automatically couple the identified GND pole to a GND connection using information from the detection circuit.
2 . An audio jack detection circuit, comprising.
a first switch configured to provide a detecting current to or to isolate a detecting current from a first connection of an audio jack;
a first comparator configured to compare a voltage from the first connection to a first reference voltage and to provide a first output; and
a second comparator configured to compare the voltage from the first connection to a second reference voltage and to provide a second output,
wherein the first and second outputs provide an indication of an impedance of the first connection of the audio jack.
3 . The audio jack detection circuit of claim 2 , including:
a control circuit configured to provide a first switch signal to control the state of the first switch,
wherein the control circuit is configured to provide the indication of the impedance of the first connection of the audio socket using the first and second outputs.
4 . The audio jack detection circuit of claim 3 , wherein the control circuit is configured to determine an impedance range of the impedance of the first connection of the audio socket using the first and second outputs.
5 . The audio jack detection circuit of claim 2 , including a current source configured to generate the detecting current.
6 . The audio jack detection circuit of claim 2 , including:
a second switch configured to automatically couple the first connection to a MIC pole to a MIC connection of a processor and to automatically couple the identified GND pole to a GND connection using the first and second output from the detection circuit.
7 . An audio jack detection system, comprising:
a current source configured to generate a detecting current;
a first switch configured to provide the detecting current to or to isolate the detecting current from a first connection of an audio socket;
a control circuit configured to provide a first switch signal to control the state of the first switch;
a first comparator configured to compare a voltage from the first connection to a first reference voltage and to provide a first output to the control circuit; and
a second comparator configured to compare the voltage from the first connection to a second reference voltage and to provide a second output to the control circuit,
wherein the control circuit is configured to provide an indication of an impedance of the first connection of the audio socket using the first and second outputs.
8 . The audio jack detection system of claim 7 , wherein the control circuit is configured to determine an impedance range of the impedance between the first connection and a first signal pin of the audio socket using the first and second outputs.
9 . The audio jack detection system of claim 8 , wherein the first signal pin is a left speaker pin and the second signal pin is a right signal pin.
10 . The audio jack detection system of claim 7 , wherein the first signal pin is a right speaker pin and the second signal pin is a left signal pin.
11 . The audio jack detection system of claim 7 , including:
the audio socket, including the first connection, the first signal pin, a second signal pin, a ground pin, and a microphone pin; and
an audio processing unit configured to provide a first audio signal to the first signal pin, a second audio signal to the second signal pin, a ground signal to the ground pin, and to receive a microphone signal from the microphone pin.
12 . An audio jack detection method, comprising:
selectively providing a detecting current to a first connection of an audio socket using a switch;
comparing a voltage from the first connection to a first reference voltage using a first comparator and providing a first output indicative of the comparison;
comparing the voltage from the first connection to a second reference voltage using a second comparator and providing a second output indicative of the comparison; and
providing an indication of an impedance of the first connection of the audio socket using the first and second outputs.
13 . The audio jack detection method of claim 12 , including:
determining an impedance range of the impedance between the first connection and a first signal pin of the audio socket using the first and second outputs.
14 . The audio jack detection method of claim 12 , wherein the first signal pin is a left speaker pin and the second signal pin is a right signal pin.
15 . The audio jack detection method of claim 12 , wherein the first signal pin is a right speaker pin and the second signal pin is a left signal pin.