CM5908/5907 Plug-n-Play Bluetooth upgrade board

[bradnic]

Count me in for 2 boards.

[djjerme]

Did someone confirm that the 5903 has the same mechanism?

[Chrisbike]

Update us!

[jaysterling]

Still working on it! Been super busy with work lately working long hours, so time on this has suffered, but certainly not stopped. It's also been a real PITA working with this CSR chip. I've pretty much figured out its quirks at this point but for awhile I was having huge troubles reliably reading/writing the EEPROM that configures the BT chip and (now I realize) mistakenly thought I kept frying the chips.

Anyway, my hope is to get a video up this weekend of it working. Pretty much all the buttons are doing the right things now according to that original faceplate pic I put up. Mic input and phone calls are working. The last thing I have to work through is the analog audio out. I've got it working, but there is digital noise in the output that's higher than I'd like, so next I'm seeing what I can do to eliminate that. The BT chip has differential outputs, then I'm using a TPA6132A headphone amp for the single-ended conversion. When I plug the output of the chip into headphones, the SNR is great, but when plugged into the stereo, the digital noise is present. I'd guess it's like -50 dB down from full scale signal, but it's there. I'm going to try running a separate 3.3V regulator just for the headphone amp with a separate ground path from the rest of the circuit, but any advice is appreciated :)

[bradnic]

you are powering the whole test rig with an actual battery and not a power supply right?

[jaysterling]

you are powering the whole test rig with an actual battery and not a power supply right?

No, I'm using a bench power supply currently. I figured power could only get noisier running on the alternator in the car, so I should get it at least working in the ideal case first. Bad idea?

[bradnic]

it probably introduces noise. best to try a battery source to make absolutely sure.

[jaysterling]

Turns out using a separate power supply and ground path totally fixes the digital noise issue like I hoped.

So it's all working now! I just made a short demo video with everything buttoned up inside and functioning. Still work to go but it's getting close.

[s1uma1]

Turns out using a separate power supply and ground path totally fixes the digital noise issue like I hoped.

So it's all working now! I just made a short demo video with everything buttoned up inside and functioning. Still work to go but it's getting close.

Omg. This is so freakin' awesome. Please please please please tell me you're gonna sell this... please please please...

[bradnic]

Home run brother. Ready to paypal you for the units i requested earlier

[Chrisbike]

Home run brother. Ready to paypal you for the units i requested earlier

[Eric]

I'd like one of these, how much?

[Boggie1688]

Turns out using a separate power supply and ground path totally fixes the digital noise issue like I hoped.

So it's all working now! I just made a short demo video with everything buttoned up inside and functioning. Still work to go but it's getting close.

Jay, sent you a PM.

[Todd Black 88]

Beautifully executed.

I am in for a few I think.

[tuckerware]

Most days I feel like a fairly intelligent person until I read a thread like this and feel like a moron. I mean, amazing accomplishment but stop showing off already. ;)

So, even though you are kind of being a dick by making us look like comparative neanderthals I really would like to give you money now for this witchcraftery.

Is it ready yet?

How about now?