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#363408 - 08/02/2015 19:55 Possible to send serial with buttons through AUX?
FieroSTi
member

Registered: 07/05/2007
Posts: 104
What I'd like to do is be able to switch to the AUX input and have the front panel buttons (or hijack IR translated values from my Pioneer remote) send serial commands through the serial port. One-way communication from the empeg is fine. No need for feedback.

So how would I accomplish this? Write a userland app that intercepts the button presses and dumps the appropriate data to the serial port (/dev/ttyS1) and change the internal mixer to take audio from the AUX jack? Could it be that simple? Looks like from this http://empegbbs.com/ubbthreads.php/topics/334459/Tuner_Interface thread I might be able to do everything I need through Hijack.

This is for a Bluetooth A2DP and AVRCP add-on module, by the by. I'd like to be able to stream Slacker or Pandora some times and this just seems like a pretty slick solution. Any thoughts, anybody?


Edited by FieroSTi (08/02/2015 20:27)

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#363438 - 10/02/2015 06:27 Re: Possible to send serial with buttons through AUX? [Re: FieroSTi]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 30592
Loc: Seattle, WA
I haven't written any software in that vein, but from what I've heard, my first guess is that yeah, you could do it entirely within Hijack. I'm pretty sure the kernel knows when the DSP has switched to the Aux input. I'll bet a Hijack patch is going to be the simplest option. Mark still accepts patches to Hijack. You could activate/deactivate the functionality, and control its options, with the Empeg's CONFIG.INI file easily. That way it could be a permanent patch to Hijack that lies dormant and only takes effect when the proper configuration entries are set up.

I love this idea. If you code it to a specific popular module that's relatively inexpensive, this would be a great way to control the audio stream coming from the smartphone in your pocket without having to dig it out and fiddle with the buttons. Which module is this? And will your typical Android or iOS device respond to AVRCP?

If you successfully implemented this, I'd definitely buy the same bluetooth module and replace my current one with it. It'd be a direct plug in replacement, I'd just have to wire up the serial connection.

One of my typical use-cases is having my phone streaming Pandora bluetooth to the Empeg's aux-in while the screen of the smartphone is showing Waze. The problem is that if I want to skip to the next Pandora song, I have to task-switch out of Waze or do similar fiddling with the iphone screen to bring up its playback controls. This is far to fiddly to do safely while driving. Whereas if I could just reach down and press Next on the Empeg. This would be brilliant if you could make it work.
_________________________
Tony Fabris

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#363444 - 10/02/2015 14:36 Re: Possible to send serial with buttons through AUX? [Re: FieroSTi]
JBjorgen
carpal tunnel

Registered: 19/01/2002
Posts: 3399
Loc: Guadalajara, MX
I too am interested in this. Would be nice to send some basic commands to the iPhone while doing Pandora and even Podcasts.
_________________________
~ John

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#363449 - 11/02/2015 01:04 Re: Possible to send serial with buttons through AUX? [Re: FieroSTi]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 13506
Loc: Canada
Yeah, sounds cool. Probably just needs a new syntax tweak to Hijack's ir_translate stuff, to designate a translation for serial-port output.

I could probably hack it up in an hour or so, except everything I own is now in a hundred or so near identical cardboard boxes, stacked in random piles (by our friends) throughout the new house.

We'll be busy here for quite some time, so don't hold your breath waiting for me to do something here anytime soon.

Cheers

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#363714 - 23/03/2015 19:40 Re: Possible to send serial with buttons through AUX? [Re: FieroSTi]
FieroSTi
member

Registered: 07/05/2007
Posts: 104
Hey, glad to hear there's interest in this. I kept forgetting to check this thread.

Fellas, I'm designing this interface around a Roving Networks RN-52 Bluetooth module. They're about $22 from Mouser or DigiKey and don't actually require much other than some power supply components. The module sports stereo analog outputs, stereo microphone inputs, several GPIO for various uses, a UART for configuration and control, a PCM interface and i2s. It really is mostly self-contained, save for a few RS232 level matching components and a power supply. I'm also considering adding an AVR with appropriate code to emulate a tuner and allow for a steering wheel remote control without the need for a tuner, because those are made of unobtanium. Now that I think about it though, doesn't the tuner plug include an i2s interface and an RS232 UART? I wonder if I could just engineer a tuner emulator module and take advantage of functionality already within hihack. I'll read up the docs on the source and see what I can actually do with Hijack if I compile from scratch.

Almost all Android devices manufactured in the last few years will support both A2DP and AVRCP. I'm not sure about iThings because I haven't owned one since iPhone3G, but I don't see why not. They all should inherently support both profiles except for iPhone2G, but I doubt anybody is using one of them. I don't know if it's required, but the RN-52 module supports iAP mode for iOS devices with a custom firmware build from RN (Microchip). I don't really know what, exactly, this mode does or how it would affect use with Android devices. I don't plan on experimenting with that.

I'm not sure if I mentioned it or not, but this module supports HFP as well, and is capable of utilizing multiple profiles at once. I do plan on integrating that. Definitely should help to bring this "car radio" back into 2015.

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#363719 - 25/03/2015 03:11 Re: Possible to send serial with buttons through AUX? [Re: FieroSTi]
FieroSTi
member

Registered: 07/05/2007
Posts: 104
I bought a book.

http://amzn.com/0672327201

I got it for $4. Can't be a bad thing, right? Should definitely cover Linux 2.2.17.

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