Hi. I’m interested in creating a project for getting bluetooth audio into my car’s stereo. The only thing making this different from a standard bluetooth audio receiver is that I need to be able to produce a 12V signal on a line to indicate to the stereo to switch to the auxiliary (CD) input when the bluetooth receiver is active and playing sound. I think I know enough to make this work with a raspberry pi and a bluetooth adapter, but I’m wondering if this is something feasible to accomplish with an arduino or something similar, which seems like a potentially simpler approach. I’m fairly unfamiliar with the arduino world and I’m curious what suggestions people here might have.
I don’t see why not. If the Arduino isn’t processing the audio info, you should be fine with even the ATiny class AVR chips. But you would need more than just the Arduino, going to need a MOSFET (Depends on the current load) and some supporting circuitry to switch the 12V load.
What is the "control signal" from the BT receiver that you plan to use to tell ... anything (RPi, Arduino, ???) ... that it is active and playing sound ? Or were you going to "look" at the actual audio output(s) somehow ? It may be all that's needed is a simple transistor circuit.jbebel:
The only thing making this different from a standard bluetooth audio receiver is that I need to be able to produce a 12V signal on a line to indicate to the stereo to switch to the auxiliary (CD) input when the bluetooth receiver is active and playing sound.
My current thinking is to use the RN-52 bluetooth module and an Arduino Pro Mini. To detect audio, the Arduino should watch for a pulse on GPIO2, which means a status change has occurred, then enter command mode by pulling GPIO9 low, send the “Q” command over the UART to query status, and read the bit for A2DP audio. If it’s set, raise a GPIO output connected to a transistor for passing 12V from the car to the stereo.
It looks like the Arduino Pro Mini can run off of 12V, although the car is sometimes up to more like 13.8, so perhaps I should still use a separate voltage regulator. I think that’s all I should need. Does this still sound reasonable and doable for a beginner?
Yes it does.jbebel:
Does this still sound reasonable and doable for a beginner?
As for the need for another regulator, have a look at these threads.
https://forum.sparkfun.com/viewtopic.php?f=42&t=39069
https://forum.sparkfun.com/viewtopic.php?f=14&t=38962 (scroll down to 5th post)