Hello,

 

I'd like to have bluetooth HF in my Roomster. I'm a bit of a hacker (in that old, prehistoric meaning) and I like to fix, make and mend things. So I've decided to make one myself. I will use XS3868 BT module with output connected to AUX IN of my Dance unit. I will also use Arduino Mini or Nano to monitor and manage bluetooth status via UART, switch the audio routes etc.

 

Let's imagine that we have switchable audio input/output on BT module:

• While the phone is not connected, the audio passes thru from AUX socket near the lighter to AUX IN in Dance
• If the phone is connected but nothing is streaming, like above
• If the phone is connected AND the A2DP protocol is in use (music streaming), AUX socket is disconnected and stereo audio goes to AUX IN in Dance
• If the phone is connected AND the HFP protocol is in use (outgoing/incoming phone call) the Dance's MUTE pin will be earthed by Arduino and left audio channel will be switched to PHONE IN in Dance.

Can anybody confirm that last point? If I ground the MUTE pin, will the HU switch to PHONE IN input and show PHONE on the display?

 

Well, ok. I've just checked it myself today, an it works as I've presumed above. So looks like everything is going to work perfectly. I will use DG333ADQ-T1-E3 by Vishay, controlled by Arduino to enable mute and switch audio routes. I should close in £40 in parts, including genuine microphone and radio plug. I will post my progress in case somebody is interested.

Nice project! 

 

Using an Arduino somewhat more advanced than the usual "how big is my sub woofer" threads on here. Please do keep us posted! 

Things are going slow, but in the right direction. I've had to order quad spdt chip once again, because by mistake I've ordered surface mount chip, and no, I'm not going to solder it. I've just received the right size one, socket mounted. I can start with PCB design work now.

https://www.dropbox.com/sc/a08hnj8lbypqost/AACm04w0_t6cSVQ1w-R2LWJGa

This is how it looks today. At first I was going to use one of arduino nano or mini pro I already have, but they are all 5V, and BT module logic is 3V3. So instead of adding logic level converter I've ordered 3V3 version of mini pro. It has only 8MHz clock, but I don't need Cray-XT3 to manage BT module. I don't have much time nowadays, but I'll finish this project. I promise.

 

https://www.dropbox.com/sc/wet66vlyf8l1mwp/AADRTPSqc7QVGAWJrY60-QGXa

 

Btw, how can I add images to posts?

If your picture is hosted on the web you can add it by pasting the URL into the box that pops up when the click the tiny "image" button ...

 

 

BTW my company won't let me access dropbox from a work computer. 

Installing microphone cable for HF and dashcam 5V power supply. But most of the work was just trying to replace beam regulator. Previous picture attached as well. Finally, I have file attachment option. Yay!

A bit of etching and soldering today. 5 position spst switch and shortened xbox360 controller's joystick will make nice controls for volume (up/down) prev/next song (left/right) and ptt/play/pause (push). I will fit it just above rear windscreen heating switch.

I suck at PCBs. I know it. Tons of airlines. Totally unprofessional. But I have only one layer of copper available. And I'm totally self-taught. So please, forgive.

I think those are called "test points" and if it's a one-off the only thing that matters is it can be made to work :clap:

For some reason all my USB>Arduino programmers died. Ordered new one, should be here soon. For now: printed, etched, ready to solder.

 

Had to modify the pcb a bit: didn't notice that DG333 will need both positive and negative voltage. Added voltage converter. One pcb went to bin along with BT module, it's amplifier was dead. The other module has non working audio play/pause pin, but I will emulate it thru arduino. I was already able to communicate with the module via UART, so the programming part should go easy. Wish I had more time...

OK, that's how it looks. Chinese people are very creative, they can sell the same (looking) BT module with the same symbol, but different pinouts. More shortcuts were needed. And the "-" from microphone is not what its says on schematics, it's for the bias control. I don't have time and patience to modify and etch another pcb, so I went into ugly prosthesis using piece of prototyping board. When I have time, I'll install it in the car. Dry tests show everything works as predicted. I'm a bit astonished.

OK, that's how it looks. Chinese people are very creative, they can sell the same (looking) BT module with the same symbol, but different pinouts. More shortcuts were needed. And the "-" from microphone is not what its says on schematics, it's for the bias control. I don't have time and patience to modify and etch another pcb, so I went into ugly prosthesis using piece of prototyping board. When I have time, I'll install it in the car. Dry tests show everything works as predicted. I'm a bit astonished.

Another example of good Chinese QC . Their lack of consistency is what annoys! Hope you get it working.

Another example of good Chinese QC . Their lack of consistency is what annoys! Hope you get it working.

Yet we still buy from them. I guess cost is our priority

Even if we don't buy from them, we still buy from them It's pretty hard to buy anything electronic that is not made in China/Hongkong/Korea.

 

The story continues. Everything works fine except... well, it does not! For some reason the serial data that Arduino reads from BT module is a bit garbled and impossible to be parsed properly. I've found that it may be caused by lower, 8MHz clocking of 3V3 Arduino Mini Pro bursting at 115200 baud rate. I don't see any other way to change baudrate in BT module than to reprogram it's eprom. I've already desoldered the chip (pictured), now waiting for soic adapter to wire it and reflash. If it fails, I'll need to go from scratch with different bt module or 5V arduino and logic converter.

 

I'm still pretty happy that's the only thing that does not work. Have learned a lot already, still new things to learn ahead.

I have finally  got into the eeprom, but I was unable to find anything regarding UART's baud rate. So this prototype goes to parts. The good news is I've found bytes containing bt module name and pairing pin, now it will advertise as ROOMSTERBT instead of PAR1007 BT, and pin will be no longer 0000. Time for new design.

Time for v2 prototype. This time Around Nano, logic level converter and by module breadboard. All programmed, tested, ready to put on PCB.

Edited 10 August, 20169 yr by Steamworx

Simpler than previous one: 5V Arduio Nano powered from 12v to USB car adapter, 4V for bluetooth module achieved by 1N4001 rectifier diode, YF08E logic converter and good, old XS3868 bluetooth module. Audio routed and phone pin grounded via good, old DG333AD quad SPDT.

Edited 14 August, 20169 yr by Steamworx

Ok, it's done. I could add a display for song titles and phonebook records, but... maybe next time. I'm going to record a movie after installation to show how it works.

Nice little project. Love this kind of tinkering!

 

Right on my kind of level. When I had my Felicia I made up a few circuits myself to enable features I wanted. I had cornering fog lights, auto close windows and auto lights (this was a pre-bought kit but I had to make up my own looms to connect to car etc).

Since my power supply has two USB sockets, I've decided to use one as phone charging option on the dashboard. Module provides 15W of power, should be enough for all USB needs.