Designing a Custom Bluetooth Upgrade

[Matthew Jeschke]

I'm slowly designing some electronics for the older trucks, NBS and before where there was no Bluetooth from the factory. The goal is to refresh my Embedded Design skills. I got a masters degree in Computer Engineering years ago and worked in the industry for 7 years but left for sales. That was nearly 12 years ago.

I want to get fresh with it all again. The first project I picked up is to design a upgrade to the existing Delco Radio in our trucks w/ bluetooth functionality. Goal is to:

- Seamless integration with Delphi head unit and harness.
- Utilize tape deck / auxiliary input controls on head unit to control playback from Bluetooth source.
- Splice into OnStar microphone to utilize hands free protocol / phone calls.

I've got most of that functionality figure out. May also add if hardware permits USB link to playback music from USB source and or phone.

Possible future capabilities I've yet to research

- Link for OBDII data (I'd LOVE this but no idea where to find an open source example) especially if I could log PIDs for tuning!
- LTE Modem for internet hotspot

 

[S33k3r]

You might could get an OBDII dongle off Amazon, and then Torque off the various phone stores. That should allow you to sniff traffic, and compare.

 

[drakon543]

as mentioned above for the obd they already sell obd2 to usb for your suggested setup. it is a corded setup for use with laptops and such. if you bought one and cut it open you would be able to get the pinning that way and then just make your own mountable usb jack that could be either hardwired into the obd2 plug or get some of the male and female plugs and design a jumper harness for easy installation.

 

[MassHoe04]

Very cool project! Would love to see it when ready.

 

[BatsTDK]

@clarkb created a similar project to this, although his is designed for the 2003-2006 models.

Need beta testers for a bluetooth adapter for 2002-2006 GM Trucks. You can keep it when we're done!

I created a prototype bluetooth adapter the integrates with the factory head unit of certain GMC trucks/SUVs 2002-2006. It was designed as a drop-in replacement for the accessory 6-cd changer in the lower dash found in many of these trucks, like my 2003 Yukon XL Denali. The steering wheel and...

www.tahoeyukonforum.com

 

[Matthew Jeschke]

Super cool! Thanks

 

[Nooj]

I'm slowly designing some electronics for the older trucks, NBS and before where there was no Bluetooth from the factory. The goal is to refresh my Embedded Design skills. I got a masters degree in Computer Engineering years ago and worked in the industry for 7 years but left for sales. That was nearly 12 years ago.

I want to get fresh with it all again. The first project I picked up is to design a upgrade to the existing Delco Radio in our trucks w/ bluetooth functionality. Goal is to:

- Seamless integration with Delphi head unit and harness.
- Utilize tape deck / auxiliary input controls on head unit to control playback from Bluetooth source.
- Splice into OnStar microphone to utilize hands free protocol / phone calls.

I've got most of that functionality figure out. May also add if hardware permits USB link to playback music from USB source and or phone.

Possible future capabilities I've yet to research

- Link for OBDII data (I'd LOVE this but no idea where to find an open source example) especially if I could log PIDs for tuning!
- LTE Modem for internet hotspot

How’s your project coming along? Are you still working on this?

Nooj

 

[Matthew Jeschke]

I haven't worked on it in a couple months. I had to rebuild all my rocker arms and re-spec pushrods, etc. Have a wild engine / top end and it wore out after 12,000 miles.

I need to get back at it though.

Progress so far...
- Got a Bluetooth board working which sinks audio from a bluetooth source and plays on a speaker

Need to do:
- Find wiring diagram for tape deck / aux input on factory head unit.
- Expand A2DP Bluetooth circuit to do stereo audio (currently just mono)
- Get a connector what plugs bluetooth board into head factory harness
- Write code to take microphone inputs for phone calls
- Design a PCB board for final circuit
- Design enclosure

 

[rplatko]

I haven't worked on it in a couple months. I had to rebuild all my rocker arms and re-spec pushrods, etc. Have a wild engine / top end and it wore out after 12,000 miles.

I need to get back at it though.

Progress so far...
- Got a Bluetooth board working which sinks audio from a bluetooth source and plays on a speaker

Need to do:
- Find wiring diagram for tape deck / aux input on factory head unit.
- Expand A2DP Bluetooth circuit to do stereo audio (currently just mono)
- Get a connector what plugs bluetooth board into head factory harness
- Write code to take microphone inputs for phone calls
- Design a PCB board for final circuit
- Design enclosure

Nice! I'm interested in you're.
Project I have an 05 suburban that I Upgraded to lux added slave cd and xm . Let me know if I can help in anyway

 

[Matthew Jeschke]

Oh cool... This has been along journey. I am a salesman by day, engineer when I have time. My background is engineering. Anyways, my time RAN really short, as my mom got sick and I had to help out the last couple years. I also got distracted and built out this YouTube channel when I should have been refreshing my engineering skillset...

https://www.youtube.com/channel/UCAqM5js7EuAyEMmAInbwTQQ

Long story short, last four months I've been studying Mobile App design. So I got the individual features working with a small embedded processor to do Bluetooth along with hands free, just need to design a circuit board for the system (I say just, could take a few months).

Then my idea is all the stuff I build will have a user interface to configure and set it up through the Mobile device. Unfortunately, so far, mobile app development has been virtually impossible. Google's Android API is the worst quality code I've ever seen. I didn't know it could be so bad. I thought I'd switch to IOS but that requires I buy a complete mac system which I don't have. I thought I'd build a virtual machine but to download the mac OS you have to have apple play store. This stuff has gotten infinitely more complex, and IMO not for the better.

Long story short, I'd love to hear your thoughts. Sounds like an XM receiver would be a nice module to have built into the board...

 

[Matthew Jeschke]

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.

 

[S33k3r]

Hopefully I'm not breaking any rules by suggesting a different forum to support your endeavor... But I suggest you check out xdadevelopers forums for this kind of stuff. There is an immense body of knowledge there, and some helpful people.

Good luck, in any case!

 

[Matthew Jeschke]

Already subscribed to one for electronics design. More or less putting comments here to see if there's any suggested features

 

[Matthew Jeschke]

Anybody who knows detailed pinouts for radio harness on GMT800 series head unit please share...

I need to start figuring out where to tie into the harness so I can get the following signals:

Remote control line ~ I assume there's a signal wire for remote control of CD changer option if there was one?

Microphone for OnStar. I'll try to tap into that line for audio input to phone / headset.

As well as... Left Aux Input, Right Aux Input, Power Line, Ground (can find these easily enough but any help is appreciated!)

 

[Matthew Jeschke]

Was able to snag a factory head unit off eBay. Now I need the harness coming off backside of the head unit so I can hook-up on my bench. Then I can probe / figure out how the signals work to control external deck tape / CD changer. I'll utilitze those signals to control the BT audio source.

Saving my notes here... Also found a link with some stuff below:

2001 Tahoe Radio Wiring Diagram - Wiring Diagram

2001 Tahoe Radio Wiring Diagram

wiringdiagram.2bitboer.com

 

[Matthew Jeschke]

 

[Matthew Jeschke]

I finally got some time and wired up this circuit. It's working like a champ. My next step is to decode Class 2 Serial data with the microcontroller. I'll have to listen to when play controls are pressed so I can send command play commands to the BT source.

Anybody know where the Class 2 Serial has been decoded or I can find a breakdown of all the data on the line?

Also anybody know how the CD changer wires up to the head unit? I'll need to use those lines to feed the audio signal into the head unit and out to the amp.

Aux Input for Delco stereo – elliotmade

elliotmade.com

I found this but requires a login to view the attachments:

ELM327 & Class 2 Serial Data

For some time now I have been pondering whether to start a new thread or update the old thread by @blurry of how to read TCCM codes. I will start this thread here today but I think I will also add an update to the Blurry thread, simplifying things and correcting a few misstatements as well as...

gmtnation.com

I started writing code to decode J-1850 but got sidetracked. The ELM327 chips will do it but I'd prefer to do it by myself so I don't have to add an expensive extra chip to design.

J1850VPW/J1850VPW.ino at master · connorwm/J1850VPW

Arduino Code (eventually library) for communicating with J1850 VPW OBD-II equipped cars. - connorwm/J1850VPW

github.com

 

[Matthew Jeschke]

I was able to decode the data yesterday lol Now to rig up a head unit, CD changer, and or tape deck so I can intercept the communications and make the head unit think the Bluetooth module is a AUX device.

 

[S33k3r]

Do you have a head unit with which you can work? Also, have you taken a look at any of the wiring harness options for aftermarket radios? I'm thinking they might could be helpful.

 

[Matthew Jeschke]

I bought a head unit from the junkyard to tinker with / right up and test out. So I have on my development bench a:

P59 PCM (Gen III SBC controller)
Delco Electronics Radio Head Unit
and the tape deck

I'm working on the circuit right now to sniff the J1850 VPW (single wire network) and decode traffic on it. I have the microcontroller rigged up. Somebody wrote a really crude program and put on GetHub. It's enough to know the data can be decoded but I need to expand on it to get everything I need. I'll probably need to make it bidirectional as well. Right now the circuit (and code) I rigged up only reads.

I found a page with description of the J1850 Signal.

https://carwhisperers.tumblr.com%2Fpost%2F46293333326