The Pulse Density Modulation (PDM) microphone (U13) on the Nordic Thingy:53™ captures audio input. The PDM microphone has also a Wake-on-Sound feature that can be used to wake up the nRF5340 System on Chip (SoC) when an audio event exceeds a set threshold. In an audio event, the DOUT pin (P0.25) is pulled high. The nRF5340 SoC can use the interrupt to start the PDM clock and sample audio data.
The following schematic describes the PDM microphone.
Figure 1. PDM microphone
For audio output, the Nordic Thingy:53 has a piezo buzzer (BZ1). The buzzer is driven by a transistor using the Pulse Width Modulation (PWM) input.
The following schematic describes the buzzer.
Figure 2. Buzzer
