The Tympan comes ready to use assuming that you want to use headphones (or ear buds). Just plug the headphones into the black headphone jack, and you’re ready to go!
But some folks have asked about using the “Line Out” outputs instead of the headphone output. Because the Line Out bypasses the headphone amplifier, the hypothesis is that the Line Out might have lower background noise than the Headphone Out. Wow. That’s a great question!
To find out, you would need to do a test. For this test, you would need to:
- Connect to the line outputs on the Tympan circuit board
- Change the Tympan software to use these outputs instead of the headphone output.
For the hardware connection, you need to take your circuit board out of its protective plastic housing. Then, on the side of the circuit board, you’ll see lots of through-holes. The ones at the bottom are for the Line Out Left and Right (“LO L/R”). Use the holes shown below. [Corrected Nov 3, 2017] The square holes are the Left and Right audio channels. You’ll also need a ground connection. Use either of the corresponding circular holes.
For the software changes, I’ve had to modify the Tympan_Library. Right now, it is not well tested, so I’ve created a new branch in the GitHub repo. You can access the branch here: https://github.com/Tympan/Tympan_Library/tree/feature_enableLineOut. I only changed the two control_tlv320aic3206.h and control_tlv320aic3206.ccp files.
What I did was add a new function “outputSelect”. You can use this function to choose either the headphone output or the line output. The headphone output is still the default, but now you could add this command (plus the argument TYMPAN_OUTPUT_LINE_OUT) to select the Line Out instead.
For a concrete example, open the Tympan example sketch “BasicGain”. Find the line:
After that line, add this new line:
Here’s a screenshot that shows how I added it to my version of BasicGain.ino:
Other than ensuring that it compiles, I haven’t been able to test it. Once I do test it, I’ll merge the code into the main library and update this thread.
Does it work for you?