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CM5908/5907 Plug-n-Play Bluetooth upgrade board

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    CM5908/5907 Plug-n-Play Bluetooth upgrade board

    UPDATE:

    Finally, the first batch of these kits will become available Wednesday, March 14th at 6 PM PST! I have 48 total kits to distribute (I am holding on to 2 of the first 50).

    What:
    A plug-n-play modification to the BMW CM5908 radio that provides Bluetooth streaming, hands-free calling, and voice assistance integrated into factory controls. It's a custom circuit board that replaces the cassette module inside the radio.

    IMPORTANT: This board will ONLY support the CM5908 at this time. CM5907 support is coming in future revision.

    How to buy:
    On Wednesday, 3/14/18 at 6 PM PST I'll create a for sale thread in the Parts for Sale section. Be on the lookout for the thread, and post a simple "dibs" post to get in line. That evening, I'll send everyone in line, (or just the first 48, depending how it goes) a private link to checkout and purchase.

    Check out the full product page and take a look at the installation procedure in the downloadable manual at cantalouperadio.com

    More details:

    - 48 total kits available
    - Limit 1 per customer
    - Kit price: $185+sh
    - Optional installation price: $65
    - Major credit cards and PayPal will be accepted at checkout

    /UPDATE

    For those that have seen my other thread documenting my hacking a slider radio to add Bluetooth and take over complete control of it, I've mentioned a simpler approach to adding Bluetooth to the radio that doesn't involve as much surgery, and that I was thinking about making it with the intent of selling. Well I'm working on it now so I'm breaking this out into its own thread to avoid confusing the two projects.

    So the goals here are:

    - Make a printed circuit board that replaces the cassette deck from the Alpine CM5908 (also will fit 5907) to add Bluetooth music streaming wired into the stereo, taking place of the cassette input
    - Integrate the functionality as much as possible into the factory interface
    - Make it easy to install and reversible. No hacking up the stereo and no soldering required (other than kit assembly if sold that way)
    - If sold as a kit, make it reasonably easy to hand-assemble

    Whereas the RaspberryCassette project takes over full control of the face by hacking into the LCD and front panel connectors, I'll pretty much only use the connections available to the cassette deck for this version.

    I'm at the point now where I have the reverse engineering done, I have a breadboard prototype I'm working on, I know the steps to get it done, and I'm ready to get some feedback, especially from those interested about whether you'd prefer a kit or money + assembled unit. More on that later.

    So I'll run through my thinking on the design. Here's the lay of the land when you open the lid on one of these:



    Outlined in magenta is the giant cassette assembly, held in by 4 screws circled in red (some occluded). The yellow boxes circle a total of 3 connectors attached to the assembly. Top left is power, top right white flex cable is transport control, and the connector at the bottom is the audio output. When the screws and connectors are removed, the assembly can be wiggled out (also best to remove the LCD first by pulling it up)

    Once it's removed, we can use the power from the power connector to run a Bluetooth audio module and output it's audio into the connector for the tape audio. I figured out where a switch needs to be used to change from radio to tape input, and that's the gist of how this works.

    Next problem was placing the input-switching button. My first thought was a push button mounted on the PCB behind the cassette door that you'd stick your finger through and push to switch. Then I realized that the volume knob actually has a clicking push switch that's used for some tuner scanning mode. Because this signal comes through a harness I can unplug (see top view above) and because no one really cares about the scanning feature, right?, I decided I'd steal that signal and use this click to switch inputs.

    Once in tape mode, the wide white flex cable carries a bunch of signals telling the deck user inputs like eject, FF, RWD, etc. I figured out the button inputs I could gather from the cable and all the LCD display elements I could control. Because of some of the complexity, I need a little microcontroller to handle these tape commands, acknowledge in some cases, signal to the Bluetooth module the commands, toggle the input source and save it to flash, etc.

    So with all that, here's what's possible and what I'm currently thinking for interface:



    The inputs I can gather are:
    - Push of volume button
    - All 4-way pad inputs
    - Button 1/EJ
    - Button 2/PROG

    I can only tell how long a button is held from the push button though. All the other inputs have pre-defined pulse lengths since they're signaled by another MCU.

    The LCD outputs I can control:
    - Switch display between "1" and "2"
    - Turn on/off the "MTL" display

    The other feature I want to implement is auto-switch input to BT if a call comes in when you're listening to the radio, then switch back at the appropriate time.

    So, any other must-have controls or indications you'd rather see? The Bluetooth module I'm going to use has a way to configure it so that a whole variety of controls can be exposed via its GPIO ports so that I can control them.

    The other big question is how I'd distribute this. There are two directions: kits, or pre-assembled units, and that affects how I design the PCB. So I'd love to know, from those interested:

    1. Would you rather save say $30 and assemble the PCB yourself, or pay it and get an assembled board ready for install? Kit assembly would probably contain about 30-40 through-hole components you'd need to populate on the board
    2. If it was only sold as a kit, would that prevent you from getting one?

    Below is where I am as of now. I'm using a PIC microcontroller which is on the red board at bottom connected up to the stereo through the breadboard. I got the firmware for the PIC working this weekend and handling the tape transport input signals and the volume push button input. I'm waiting on a few bits and pieces but hopefully will have a fully working prototype soon. I'm really happy with how this one is coming along, it's a much more elegant and functional integration than I originally thought was possible and I'm excited to get it into some people's hands!

    Last edited by jaysterling; 03-10-2018, 03:30 PM.

    #2
    As much fun as it would be to solder each component on myself, I'd inevitably screw something up. Especially considering the relatively small size. More importantly when something goes wrong...I'll be asking you what is broke. 😀

    As much as I want to say, have both! I think my vote goes for preassembled.

    The work you are doing is amazing!

    Comment


      #3
      preassembled!

      Comment


        #4
        Originally posted by s1uma1 View Post
        preassembled!
        I concur. Just found a beautiful example of a CM5908. So excited for this. I hate the aftermarket radio that my iX came with when I bought it, looks like poo. ;D
        Build Thread
        https://www.r3vlimited.com/board/sho...d.php?t=419655
        Parts Thread
        https://www.r3vlimited.com/board/sho...d.php?t=408302

        Comment


          #5
          Good to know, thanks for the input guys. Doing PCB assembly tech support is not something I'm really looking to get in to hah. I'll work towards doing a pre-assembled board.

          Comment


            #6
            Originally posted by jaysterling View Post
            Good to know, thanks for the input guys. Doing PCB assembly tech support is not something I'm really looking to get in to hah. I'll work towards doing a pre-assembled board.
            😉 I thought that would nudge you.

            Comment


              #7
              Definitely preassembled, I'd also be in for two of these, possibly 3 depending on price.
              My Garage
              2001 Z3 2.5i Steel Gray/Black (Lexi)
              1988 325ix Diamond Schwartz/Black (Izzy)
              1989 325i Cirrus Blue/Houndstooth (Stitch)
              Feedback

              Instagram: Stone.Hopkins

              Comment


                #8
                I'm in either way. I can't wait for this. I would love to use an original stereo


                Sent from my iPhone using Tapatalk

                Comment


                  #9
                  +2

                  I would be in for a complete fancy ass version also, if you would do it. LCD hacked etc. I may find it hard to remember what the MTL means on/off, etc
                  Originally posted by codyep3
                  I hope to Christ you have looks going for you, because you sure as fuck don't have any intelligence.
                  2001 silver/Blk 325 cabby. SOLD
                  1988 Blk/Blk e30 factory wide body kit car SOLD
                  1992 DS/BLK 325 m-tech II apperance pack cabby SOLD!
                  2002 325xit Sil/blk. SOLD
                  2012 328i xdrive touring. Wht/blk. SOLD
                  2009 135 cabby. monacoblue/blk leather SOLD
                  2007 Z4m coupe. Silver grey/black/ aluminum. 1of50
                  2010 F650gs twin
                  2016 M235i cabby. Mineral grey/Red leather

                  Comment


                    #10
                    Depends on the price point and if you're requiring SMT components. I don't have an SMT setup any more, but if it was a partially assembled kit with regular components loose for a savings in cost, I'd be down with that!
                    1991 325i MT2 Touring (JDM bro)
                    2016 Ford Flex
                    2011 Audi A3 - wife's other German car

                    Comment


                      #11
                      I would love to buy it as a kit but I think it would be great to have the pre-assembled option for those who aren't as interested. I'm very interested to see how this goes because i will happily purchase one when they're ready
                      84 325e, Saphirblau Metallic/Houndstooth Sport, OBD-2 M52B28/ zf320

                      Comment


                        #12
                        Count me as a yes for kit. I always prefer to build it myself.
                        1991 325i MT2 Touring (JDM bro)
                        2016 Ford Flex
                        2011 Audi A3 - wife's other German car

                        Comment


                          #13
                          Preassembled!


                          Sent from my iPhone using Tapatalk

                          Comment


                            #14
                            I got a CM5908 on the shelf waiting
                            Build Thread
                            https://www.r3vlimited.com/board/sho...d.php?t=419655
                            Parts Thread
                            https://www.r3vlimited.com/board/sho...d.php?t=408302

                            Comment


                              #15
                              Pre-assembled makes the most sense, I assume with pre-assembled you'd be going SMT route and as compact as possible?

                              I work with SMT all day, so whichever route you go, I would like to be able to order an unpopulated board.

                              Alpine makes this radio right? I wonder if the signaling is common with their other BMW radios, like the C33. I have one laying around from my E36.

                              Comment

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