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Bluetooth headset

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itzme

New Member
Hi all,
I would like your opinion on something. Im currently doing a school project and it requires me to use a Bluetooth headset as the receiver for my tone. I am then to perform signal converison. However, the Bluetooth headset would not function when it's charging. There are 3 wires from my Bluetooth headset. 2 outputs and one ground. Since it wont be able to function when it's charging, im having difficulty grounding it. When the output is observe on the oscilloscope, it needs to be grounded to form a close loop else the output cant be observe. When the headset is connected to my circuit, the ground from the headset needs to be separated from my power source ground. To observe the output from the osilloscope, the headset ground needs to be connected to the oscilloscope. Both are not connected to the power source ground. Does it mean im nt grounding my headset at all?:confused:
 

Sceadwian

Banned
How are you getting the audio from the bluetooth headset? Via an audio jack or are you tapping into the speaker output directly?
 

itzme

New Member
How are you getting the audio from the bluetooth headset? Via an audio jack or are you tapping into the speaker output directly?
oh, it's from the headphone. Erm, is it called an audio jack? Im not sure. But it's a wire that u plug into the headset on one end and another end is the headphone.
 

Sceadwian

Banned
The ground is on that wire already. If it's stereo it'll have three contacts, left right and ground, if it's mono it'll have two, signal and ground. Even if you connect them backwards it's not important, they're AC coupled, so either one can be ground.
 

itzme

New Member
The ground is on that wire already. If it's stereo it'll have three contacts, left right and ground, if it's mono it'll have two, signal and ground. Even if you connect them backwards it's not important, they're AC coupled, so either one can be ground.
Thanks so much for your advice! Appreciate it! Does it mean that when I input the signal into my ADC chip it is not neccessary to ground it already? All i need to do is input the signal wire to the ADC chip inpuy? :p
 

Sceadwian

Banned
You have two wires, ground one, feed the other into the ADC.
 

itzme

New Member
Thanks so much for your advice! Appreciate it! Does it mean that when I input the signal into my ADC chip it is not neccessary to ground it already? All i need to do is input the signal wire to the ADC chip inpuy? :p
Does it mean I need a separate ground to it? Because I've i were to share the same ground with my ADC and Power source ground, it means im providing -5V and i wont be able to observe any output. Does it mean I need a separate ground for the headset and not share the same ground with the power source?
 

itzme

New Member
You have two wires, ground one, feed the other into the ADC.
Does it mean I need a separate ground to it? Because I've i were to share the same ground with my ADC and Power source ground, it means im providing -5V and i wont be able to observe any output. Does it mean I need a separate ground for the headset and not share the same ground with the power source?
 

Sceadwian

Banned
Use a diode to cut off the - portion of the incoming signal, if you're just doing tone detection you don't need it.
Just out of curiosity, does this tone detection you're using carry any other sound? Like voice or ambient noise? Because if it doesn't you can feed the audio directly into a Digital I/O line (without an ADC) on the PIC and simply measure the number of I/O transistion in a fixed time frame to determine the frequency.
 

itzme

New Member
Use a diode to cut off the - portion of the incoming signal, if you're just doing tone detection you don't need it.
Just out of curiosity, does this tone detection you're using carry any other sound? Like voice or ambient noise? Because if it doesn't you can feed the audio directly into a Digital I/O line (without an ADC) on the PIC and simply measure the number of I/O transistion in a fixed time frame to determine the frequency.
Im using tones with different frequency. And the perform analog to digital conversion. Do i still need the diode? Or jst ground the earth of the headphone separately from the power source? Erm, it doesnt carry any other sound as it has already been filtered by the headset. :)

Erm, I cant feed it into the PIC directly as the PIC accepts only digital data and for my project Im required to use an external ADC. [=

Anyway since Im performing ADC so i can differentiate the different frequency for each tone and feed it into the PIC. So, im still confused what should i do to the earth of my headphone. Thanks
 

Sceadwian

Banned
A PIC can only deal with digital data, but that doesn't mean you can't feed it an analog signal. As long as you don't violate the I/O pin's max and min voltage and the signal contains only a single tone you can read it directly from a digital I/O pin. A small signal diode can cut the negative part of the signal off and a zener can limit the maximum voltage to protect the I/O line. Ground one side of the headphone to the ADC ground, use a diode to short the negative half of the audio to ground, then your ADC will only read the positive portion of the signal, which is fine for tone detection.
 

itzme

New Member
A PIC can only deal with digital data, but that doesn't mean you can't feed it an analog signal. As long as you don't violate the I/O pin's max and min voltage and the signal contains only a single tone you can read it directly from a digital I/O pin. A small signal diode can cut the negative part of the signal off and a zener can limit the maximum voltage to protect the I/O line. Ground one side of the headphone to the ADC ground, use a diode to short the negative half of the audio to ground, then your ADC will only read the positive portion of the signal, which is fine for tone detection.
Do u mean from the headset i connect it to a diode and then ground it? Do u have any reference that I can refer to? I'll really appreciate that. thanks
 

Sceadwian

Banned
1N4001 is a rectifier diode, it might work, but you need a small signal diode. Not sure what to suggest.
 

itzme

New Member
1N4001 is a rectifier diode, it might work, but you need a small signal diode. Not sure what to suggest.
THANKS! I'll try with the 1N4001 diode and if it doesnt work i'll test it with the small signal diode. Thanks so much for your advice! ;)
 
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