You'll need a soldering iron and solder, as well as some wire.

Feather Assembly

We are building this project around the FeatherWing Doubler to connect the Feather M4 Express and Adalogger FeatherWing.

You could also use Feather Stacking Headers for a different form factor, to have the boards stacked on top of each other rather than next to each other. Decide what you'd like to do, then plan ahead accordingly!

In this example, we'll solder male headers onto the Feather M4 Express and FeatherWing, and female headers onto the FeatherWing Doubler.

Follow the instructions for attaching male headers to your Feather board. It helps to use a solderless breadboard to get the headers on straight.

Do the same for the Adalogger FeatherWing, attaching male headers.

Attach female headers to the FeatherWing Doubler. You can use one your soldered feathers to help keep the female headers straight while you solder.


Headphone Jack

We'll be playing the audio from the Feather M4 Express through this headphone jack. We'll solder the headphone jack and some other components to the FeatherWing Doubler, under where the Feather M4 Express will go. The Feather M4 Express should go into the right Feather slot, in case you'd like to attach a LiPo battery.

Frtizing diagram

The headphone jack can fit under the Feather M4. I've moved the Feather M4 to the side so we can see where the headphone jack and other components go.

The middle three pins of the headphone will be connected to ground. You can connect them to the Doubler ground rail.

The outer pins of the headphone jack should be connected in series through a 100uF capacitor and a 100 ohm resistor to the Feather M4's A0 and A1 pins. Make sure the cathode sides of the capacitors are connected to the headphone jack. The A0 output (in green) will be the audio left channel and the A1 output (in blue) will be the audio right channel.

circuit schematic

Here is a schematic of the circuit. Note that pin 1 of the stereo jack is the middle physical pin. Pins 3 and 4 are the next two inner physical pins. Pins 1, 3, and 4 are all electrically connected to ground. Note that they are not connected to pin 2.

diagram from headphone jack datasheet
bottom view of Doubler with middle three pins of headphone jack connected to Doubler ground rail
top view of FeatherWing Doubler
the assembled device

This guide was first published on May 20, 2020. It was last updated on May 20, 2020.

This page (Assembly) was last updated on May 11, 2020.

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