Power Pins

• VIN - this is the power pin. It can be powered with 3.3 to 5VDC, however, the data lines are 3.3V logic only. If you want to use the speaker output, you need to provide 5V.
• GND - common ground for power and logic

I2C Logic Pins

This I2S DAC requires I2C configuration! You will need a microcontroller with our library (Arduino, CircuitPython or Python) to set up the board for audio playback.

• SCL - I2C clock pin, connect to your microcontroller's I2C clock line. There's a 10K pullup on this pin.
• SDA - I2C data pin, connect to your microcontroller's I2C data line. There's a 10K pullup on this pin.

I2S Pins

• DIN (Data In) - This is the pin that has the actual data coming in, both left and right data are sent on this pin, the WSEL pin indicates when left or right is being transmitted.
• WSEL (Word Select or Left/Right Clock) - this is the pin that tells the DAC when the data is for the left channel and when it's for the right channel.
• BCK (Bit Clock) - This is the pin that tells the amplifier when to read data on the data pin.
• MCK (Main clock, optional) - This pin is optional for the TLV320DAC3100 because you can configure the I2C driver to use BCK as the PLL input.

Audio Output

You'll want to disable speaker output when using the headphone output for the best possible sound quality. The class-D amplifier for the speaker can cause some noise on the headphone output.

Speaker

• SPK+ - This is the speaker positive output
• SPK- - This is the speaker negative output
• The speaker output is also available via the JST-PH port

Headphone

• HPR - This is the right channel headphone output
• HPL - This is the left channel headphone output
• 3.5mm output jack - This is the onboard headphone jack. It can provide stereo audio that can connect directly to your 16Ω headphones.

Additional Pins

• MIC and BIAS - MIC is the mic detection pin and BIAS is the microphone bias pin. These pins are connected to the 'fourth' contact on the 3.5mm output jack. The fourth contact is for headsets that often have a microphone. You can configure the amp to provide a 2V bias voltage which will let you detect when a headset with a mic is plugged in, and also detect when the headset button is pressed. 
• AIN1 and AIN2 - These pins are alternative mix-ins for the audio outputs (not I2S encoders).
• IO - This is an additional GPIO pin that can be used as an interrupt line.
• RST - This is the reset pin.

Mic Detect Jumper

On the back of the board is the mic detect jumper. By default, the mic contact from the headphone jack is connected to the mic detect pin on the DAC. If you cut the jumper, you can disconnect the mic contact from mic detect and then solder the center pad to the GND pad.