Connecting audio signals together

[ikalogic]

Hi there,

I need to connect the audio signal coming from this BT module (BT.PDF) to the WM8783 (we need to use that device for its low cost!)

I undertand about DC blocking capacitor (I intend to use ~1uF). The problem is that the BT module outputs 3 signals:
- Right
- Left
- AOM (Audio ouput comon, which is fixed at 0.9V, and should not be grounded!)

The WM8783, on the other hand, has only 2 inputs:
- Right
- Left

What is the best way to connect both devices?

Should i just ignore the audio output common (AOM)?

Here is what i intend to do, simply:

(MOD 2 is the BT module)

Should i put some voltage divider before the DC blocking caps, in case i need to decrease signal amplitude?

Are there some rule of thumbs i should consider or some advice you could share ?

Thanks a lot in advance.

 

[Mike odom]

If both chips have the same power supply/grounds, then you can probably ignore the audio common. If not, then you'll need to tie it to the input devices ground thru a resistor.

As far as dividing resistors on the inputs, depends. What's the max input allowed by the input device? What's the max output expected from the output device?

 

[Mike odom]

The 40mW into 32 ohm speaker in the BT spec yields about 1.1V, which is pretty close to line in/line out, so unless the input device is a massive amplifier, you're probably ok straight in.

 

[ikalogic]

Perfect!

Thanks a lot for the info!

That helps a lot