I brought this up in an other thread but realized maybe it should be its own discussion as there could be other implications.
With our radios XM comes in from a separate module that is controlled via class 2 serial data and then receive an audio input via 3 wires, radio left, radio right, and common (i'm assuming these are line level). Why is this interesting? A lot of us like to listen to the music on our phones but we also like to listen to XM. And myself personally I use my phone a lot for navigation. The problem is (and this really comes into play for another setup where we can display and control our phones on our touchscreens via a mimicsX2) that if you are listening to XM and have your phone audio plugged in you'll miss your nav directions.
Phones are very good about not broadcasting "dead signals", in otherwords the headphone jacks only send a signal when your phone is generating audio, a lot of this has to do with bluetooth power management but it comes into play on the hardwired headset as well.
This all leads into using an automatic A/B line level switch. What this would do is allow you to listen to XM radio normally as we would convert the outbound pins from the XM controller into RCA, plug them into the input A (constant) and have the RCA output connected into the wires running into the headunit. You would then have your phone connected with a mini to RCA adapter to the B (sensing) input and then when you play either music, navigation, or whatever you would it would sense the signal and switch to the B input.
Clip 3 wires coming out of XM module- BN/WH (L Audio +) D-GN/WH (R Audio +) and YE/WH (common) (see wiring diagram below)
Connect these to the wires coming out of the module:
Each blue wire gets a plus, the white wires connect to the common.
Connect the two RCAs into the A Input of this:
Connect a stereo RCA to (trs) headphone adapter to your phone and then to the B input of the switch. We'd have to play with the sensitivity to see what works best but the delay should be very low so nav instruction start immediately
Take a second set of the 2 channel speaker adapter and connect the RCA side to the output of the switch and the wires to the wiring going back into the headunit same as the input (blues to +, whites to common)
Theoretically you would now have factory style nav interrupt (maybe a call interrupt too?) that you can use with XM radio.