I2S Amplifier

• The grey square located in the center at the top of the BFF is the MAX93785 I2S amplifier chip. It supports digital audio.

Speaker Connector

• This two-pin PicoBlade-compatible speaker connector, located at the center of the BFF, is meant for plugging in a 4-8Ω, 3W-or-less speaker.
• To connect a speaker with bare wires, you'll want to pick up this cable.
• If you need a speaker, this speaker is an excellent place to start.

I2S Pins

These pins are compatible with ESP32-series, nRF52840 and RP2040 microcontroller boards.

• A0 - This is used for audio data, or DIN.
• A1 - This is used for wordselect clock, or LRC.
• A2 - This is used for bitclock, or BIT.

These pins will not work with the QT Py SAMD21 microcontroller board. To use a SAMD21, you would need to cut the pin jumpers and rewire the traces to compatible pins.

I2S Default Pin Jumpers

There are jumpers on the I2S pins to enable you to change the default QT Py pins.

First, cut the trace on the jumper associated with the default pin. Next, solder a wire between the jumper pad furthest away from the pin label on the silk and the desired QT Py pin.

• A0 jumper - Cutting this trace enables you to reassign the DIN (audio data) to a different pin.
• A1 jumper - Cutting this trace enables you to reassign the LRC (wordselect clock) to a different pin.
• A2 jumper - Cutting this trace enables you to reassign the BIT (bitclock) to a different pin.

The pads highlighted in magenta in the image below are the correct pads to wire to a new pin.

I2S Through-Hole Pads

You can use these through-hole pads to connect the I2S pins to different QT Py pins. They are labeled on the back of the board.

To reassign an I2S pin, cut the trace on the jumper associated with the default pin, and then solder a wire between the through-hole pad and the desired QT Py pin.

• DIN - This pad, located next to the A0 pin label on the board silk, is connected to the DIN pin.
• LRC - This pad, located between the DIN pin and the MAX93785 chip, is connected to the LRC pin.
• BIT - This pad, located near the A3 pin label on the board silk, is connected to the BIT pin.

Left/Right Channel Jumper

This jumper allows you to choose between the left channel, right channel, or both together.

• The BFF defaults to stereo mix, using both the left and right channel equally if no changes are made to this jumper.
• If you solder the pad near the R label on the board silk and the center pad together, you will get audio out of the right channel only.
• If you solder the pad near the L label on the board silk and the center pad together, you will get audio out of the left channel only.