Cannot pair bluetooth transmitter to iPhone

[MikeFromMesa]

I have a bluetooth transmitter/receiver and I have been using it as a receiver to listen to audio books. My earbuds are wire connected to the device and it is bluetooth paired with my iPhone. Out of curiosity I tried to do a bluetooth paring with the device set as a transmitter, and could not. The iPhone never saw the bluetooth pairing request, so I tried the same thing with 2 other bluetooth transmitters and, again, had no success.

Is there some reason my attempt to pair a bluetooth transmitter to the iPhone does not work while the receiver pairs with no problem? Is that a restriction?

 

[MacInWin]

What is this BT "transmitter/receiver?" All BT devices transmit and receive, but the various protocols may or may not be compatible. And how pairing is achieved depends on how the various devices are configured.

Out of curiosity I tried to do a bluetooth paring with the device set as a transmitter, and could not. The iPhone never saw the bluetooth pairing request, so I tried the same thing with 2 other bluetooth transmitters and, again, had no success.

And that makes no sense to me at all. How do you set whatever device this is to be a "transmitter?" Remember, ALL bluetooth devices transmit and receive, so what do you mean? That is a very confusing description to me, sorry.

 

[MikeFromMesa]

What is this BT "transmitter/receiver?" All BT devices transmit and receive, but the various protocols may or may not be compatible. And how pairing is achieved depends on how the various devices are configured.

And that makes no sense to me at all. How do you set whatever device this is to be a "transmitter?" Remember, ALL bluetooth devices transmit and receive, so what do you mean? That is a very confusing description to me, sorry.

No. That is incorrect. You can buy bluetooth devices that are only transmitters, that are only receivers or are both. As for switching between tx and rx mode, see photo below.

I have 3 bluetooth devices that are specifically built for listening to the TV or iPhone or other audio device. One is a Tx/Rx, one is a Tx only and one is a Rx only.

I can pair the Tx/Rx device with my iPhone when it is set to Rx, and I can pair the Rx only device with my iPhone, but I can not pair either the Tx only device or the Tx/Rx device when it is set to Tx with my iPhone.

 

[MacInWin]

Bluetooth has two kinds of devices. One is a Main device, and the other is the Follower.

From:

Bluetooth - Wikipedia

en.wikipedia.org

A main BR/EDR Bluetooth device can communicate with a maximum of seven devices in a piconet (an ad hoc computer network using Bluetooth technology), though not all devices reach this maximum. The devices can switch roles, by agreement, and the follower can become the main (for example, a headset initiating a connection to a phone necessarily begins as main—as an initiator of the connection—but may subsequently operate as the follower).

Both the Main and Follower transmit and receive. That is how they negotiate a connection. The headset, for example, transmits an "I'm here" signal that is received by the phone. The Phone then transmits a "let's talk" signal to the headset and they then swap information about protocols, addresses, etc. Both of them transmit and receive during that process. At some point they finalize the pairing and the agreed audio is transmitted from the phone to the headset. The headset also transmits the agreed signals back to the phone to pause the play, adjust volume, answer the phone when it rings, etc, etc.

So, both devices transmit and receive. All BT devices do that.

But good luck with your device, whatever it is. You didn't answer the question. Maybe somebody else can help you.

 

[MikeFromMesa]

Yes. Communication devices have to negotiate to set up a connection, and that negotiation (handshake) requires 2 way communications so that the sender knows that the receiver can hear it and can respond. And yes, these handshakes can differ depending upon what the particular protocol is, but I was referring to the data communications, not the control communications.

My receiving device can send some data to the sending device - connect, stop, start, disconnect and possibly some other protocol commands, but it does not send data. If I am on a phone call I can hear, but no response that I make is actually delivered to the iPhone. And more to the point, when the Tx/Rx device is set to Tx it will not pair, and the Tx only device (yes, there ae such things. See the description in the screen shot below) will not pair.

You said that I did not answer your questions, but I don't see what question you asked that I did not address. Perhaps I misunderstood your post?

 

[pm-r]

Is there some reason my attempt to pair a bluetooth transmitter to the iPhone does not work while the receiver pairs with no problem?

Why not contact the support department of the company that made your bluetooth transmitter/receiver and see if they don't have a solution for you.

Maybe something that you are trying is not compatible???



- Patrick
=======

 

[MacInWin]

The question was "what device" are you talking about. From the image, I think it is this:

https://www.amazon.com/dp/B00QV77YIC/?tag=macforums0e4-20

But that does not show any Rx/Tx or SPDIF/AUX switch on the box, so maybe it's something entirely different.

Bottom line: Until we know what device, it's hard to help.

I have no idea what that switch would be for at all. Not if it's the same as the one I found on Amazon.

So, again, what device is it? Did it have any user manual or guide?

 

[ferrarr]

When you want to transmit, you need the transmitting device to see the receiving device.

Have you tried the transmitters with a different PC/Mac/Android device?

 

[MacInWin]

Crazy, wild, thought. Could the Rx/Tx switch determine in which direction the audio flows (not the BT, that is bi-directonal, as I said)? The one I found is one-way for the audio, from the TV or amp to the headphones, not the other way. Could it be the model you have is something different, and can be used to stream FROM a BT source, like an iPhone, TO an amplifier or TV? If so, I guess the Rx/Tx switch could set the protocols in the Homespot to switch directions of the audio. TX would be for the box to send audio to the headphones, RX would be to receive audio and play it back through the plugs to the connected TV/AMP. But that only makes sense if you have it plugged into the INPUT on the TV/Amp and not the OUTPUT. Bit of a stretch there, which makes it the crazy, wild guess.

If that is the case, and it's a wild guess, then what you described, sending TV audio through the Homespot to the iPhone, probably doesn't work because of the wrong protocol. The iPhone CAN receive audio over BT, for BT headsets with microphones, for example, but I bet that Homespot doesn't use that protocol.

If that guess is correct, then the other switch may apply. It's labelled SDPIF, which MIGHT be this, taken from the same article I linked earlier:

Service Discovery Protocol[edit]​

The Service Discovery Protocol (SDP) allows a device to discover services offered by other devices, and their associated parameters. For example, when you use a mobile phone with a Bluetooth headset, the phone uses SDP to determine which Bluetooth profiles the headset can use (Headset Profile, Hands Free Profile (HFP), Advanced Audio Distribution Profile (A2DP) etc.) and the protocol multiplexer settings needed for the phone to connect to the headset using each of them. Each service is identified by a Universally Unique Identifier (UUID), with official services (Bluetooth profiles) assigned a short form UUID (16 bits rather than the full 128).

Your image shows it set to AUX, which has no meaning in the BT protocols, but if SDPIF refers somehow to the SDP protocol, moving it to that option might let it connect. Whether or not it will work is another question, as it has to appear to be a headset/mic combination to the iPhone for the iPhone to accept it as a working device.

But I do have to say that is the worst labelling on a BT device I have ever seen. The manual better be really clear on what all those non-standard things mean in standard terms.

 

[MikeFromMesa]

The question was "what device" are you talking about. From the image, I think it is this:

https://www.amazon.com/dp/B00QV77YIC/?tag=macforums0e4-20

But that does not show any Rx/Tx or SPDIF/AUX switch on the box, so maybe it's something entirely different.

Bottom line: Until we know what device, it's hard to help.

I have no idea what that switch would be for at all. Not if it's the same as the one I found on Amazon.

So, again, what device is it? Did it have any user manual or guide?

As I wrote in my previous post I have 3 of these bluetooth devices. One is a Tx/Rx device, and that is what was in the first photo I posted. One is a Tx only device, and that is what was in the second photo I posted.

The Tx/Rx device is from TaoTronics and the Tx only is from Homespot, both purchased from Amazon. The TaoTronics Tx/Rx device will pair when set to Rx but will not pair when set to Tx, and the Homespot Tx only device will not pair at all. I have tri ed with my iPhone, an old Android phone and my MacBook Pro, and all act the same way.

I have assumed that the devices will not pair in Tx mode because of some limitation in the design of the MBP and the iPhone, but I don't know what that might be. Perhaps they are designed to only pair with Tx devices? I just don't know, and that is what I was asking. That is, has anyone successfully paired a BT Tx device with an iPhone or a MBP?

I do have a manual for the Homespot and have followed the directions, but it just does not show up on either my iPhone or MBP when trying to pair, and the TaoTronics also does not show up on those devices when it is set to Tx and trying to pair.

 

[MikeFromMesa]

When you want to transmit, you need the transmitting device to see the receiving device.

Have you tried the transmitters with a different PC/Mac/Android device?

Yes. It will not show up on any of my devices. I have tried 2 different iPhones (12 and X), an older Android phone and my MBP. Does not show up on any of them, so I assumed that perhaps there was some built-in limitation as to what kind of BT device you can pair with them, and that is why I posted the question.

 

[MikeFromMesa]

Crazy, wild, thought. Could the Rx/Tx switch determine in which direction the audio flows (not the BT, that is bi-directonal, as I said)? The one I found is one-way for the audio, from the TV or amp to the headphones, not the other way. Could it be the model you have is something different, and can be used to stream FROM a BT source, like an iPhone, TO an amplifier or TV? If so, I guess the Rx/Tx switch could set the protocols in the Homespot to switch directions of the audio. TX would be for the box to send audio to the headphones, RX would be to receive audio and play it back through the plugs to the connected TV/AMP. But that only makes sense if you have it plugged into the INPUT on the TV/Amp and not the OUTPUT. Bit of a stretch there, which makes it the crazy, wild guess.

If that is the case, and it's a wild guess, then what you described, sending TV audio through the Homespot to the iPhone, probably doesn't work because of the wrong protocol. The iPhone CAN receive audio over BT, for BT headsets with microphones, for example, but I bet that Homespot doesn't use that protocol.

If that guess is correct, then the other switch may apply. It's labelled SDPIF, which MIGHT be this, taken from the same article I linked earlier:


Your image shows it set to AUX, which has no meaning in the BT protocols, but if SDPIF refers somehow to the SDP protocol, moving it to that option might let it connect. Whether or not it will work is another question, as it has to appear to be a headset/mic combination to the iPhone for the iPhone to accept it as a working device.

But I do have to say that is the worst labelling on a BT device I have ever seen. The manual better be really clear on what all those non-standard things mean in standard terms.

As part of my troubleshooting I have tried all 4 switch settings and the only setting that I can pair with is the Rx-Aux. With all 3 other combinations my iPhone, Android phone and MBP does not show the device attempting to pair, so I can not pair with them.

As for the device using the wrong protocol, if the device will pair in Rx-Aux then it clearly is using the correct protocol. It seems as though the handshake in all other settings is failing and it has seemed to me from the start that that failure is likely do to restrictions built into the phones and computer I am using. It is hard for me to credit that the BT device is using the correct protocol in only 1 of 4 settings, and seems much more likely that there is some built-in restriction as to pairing with a Tx device. That is why I asked that question in my first post.

Is there some reason my attempt to pair a bluetooth transmitter to the iPhone does not work while the receiver pairs with no problem? Is that a restriction?

 

[MacInWin]

Is there some reason my attempt to pair a bluetooth transmitter to the iPhone does not work while the receiver pairs with no problem? Is that a restriction?

Yes, you cannot stream audio INTO the iPhone except through an earphone/microphone combination that conforms to the appropriate BT protocol for two-way audio, which apparently those boxes don't support. Ditto for the Mac. Those boxes appear to have been designed to accept audio IN and send it to headphones. And the one with the TX/RX switch apparently doesn't support the protocols supported in the Mac and iPhone for two way audio. Hence, no pairing because they cannot agree on a protocol.