OP
OP
Matthew Jeschke
Full Access Member
Back to working on this. I'm working to startup a custom fab engineering business. May have landed first customer. However, I have to get back up to speed. Been spending last week reviving this bluetooth project and studying my old skillset.
My breadboarded project can do stereo audio sink from a bluetooth source (e.g. phone). Haven't figured out bidirectional / full duplex for taking phone calls yet. I think maybe somewhat limited in that.
Bidirectional uses Hands Free Protocol, HFP. I found a library and I think the chip I have supports it. However, the audio is a bit lower quality. I think this is currently how head units handle music streaming all be it a touch degraded quality.
Found a VERY well written Advanced Audio Distribution Profile, A2DP. This is CD quality audio over bluetooth. Got up and running with it pretty quickly. Trying to figure out how to code the control buttons so you can use the head unit to play, pause, next track, etc when audio sourced from phone. Only caveat is, this protocol doesn't support headsets as in HFP for full duplex audio you'd need for taking calls. I think I can stream microphone data over A2DP protocol to phone BUT phone won't detect / use it for phone calls.
Fall back maybe a jumper where person can select using device as a HFP / headset OR A2DP but not both.
I think I can get up and running with a circuit board for A2DP pretty quickly. My cost is probably going to be around $1000 materials & fab plus time to prototype. Kind of thinking about holding out till I can add USB connection for data and charging (like old iPod car hookup for music), and a microSD slot for loading music to play. Then you could play downloaded stuff on an SD, USB Thumb, Phone via physical connection OR bluetooth along with fast charging port. That would take a bit more time which I may or may not have.
Of course the concept is for this to seamlessly plugin inline with the factory head unit harness, for what I'd coin seamless integration. Would provide those of us who like a factory look & head unit with more modern aftermarket functionality.
My breadboarded project can do stereo audio sink from a bluetooth source (e.g. phone). Haven't figured out bidirectional / full duplex for taking phone calls yet. I think maybe somewhat limited in that.
Bidirectional uses Hands Free Protocol, HFP. I found a library and I think the chip I have supports it. However, the audio is a bit lower quality. I think this is currently how head units handle music streaming all be it a touch degraded quality.
Found a VERY well written Advanced Audio Distribution Profile, A2DP. This is CD quality audio over bluetooth. Got up and running with it pretty quickly. Trying to figure out how to code the control buttons so you can use the head unit to play, pause, next track, etc when audio sourced from phone. Only caveat is, this protocol doesn't support headsets as in HFP for full duplex audio you'd need for taking calls. I think I can stream microphone data over A2DP protocol to phone BUT phone won't detect / use it for phone calls.
Fall back maybe a jumper where person can select using device as a HFP / headset OR A2DP but not both.
I think I can get up and running with a circuit board for A2DP pretty quickly. My cost is probably going to be around $1000 materials & fab plus time to prototype. Kind of thinking about holding out till I can add USB connection for data and charging (like old iPod car hookup for music), and a microSD slot for loading music to play. Then you could play downloaded stuff on an SD, USB Thumb, Phone via physical connection OR bluetooth along with fast charging port. That would take a bit more time which I may or may not have.
Of course the concept is for this to seamlessly plugin inline with the factory head unit harness, for what I'd coin seamless integration. Would provide those of us who like a factory look & head unit with more modern aftermarket functionality.
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