James Lewis writes on Hackster about this STM32-based development board is ideal for low-power sound applications:
Mothra Is an Acoustics Laboratory on a Stick
Many development boards feature a plethora of sensor types intended for prototyping an IoT device. Among those types are generally one sound sensor and one vibration sensor. Kris Winer, a one-person maker shop, is developing a purpose-specific sensor board containing multiple types of the same sensors. That board is Mothra, an acoustics laboratory on a stick.
The difference Mothra offers over traditional “all-in-one” sensor boards is that it only has two types of sensors: microphone and accelerometer. However, it has two of each, giving the board high sensitivity and offering very low-power sleep modes where either type of event can wake the microcontroller.
For the microcontroller module, Winer is using the STMicroelectronics BLE-enabled STM32WB. This module contains two microcontroller cores and a Bluetooth Low Energy radio. We hesitate to say “dual-core” because the cores are not at parity. One is an Arm Cortex-M0+ running at 32 MHz focused on BLE operations. While the other is an Arm Cortex-M4F running at 64 MHz and intended as the application processor. The module has 1 Mbyte flash, 256 kByte SRAM, and 68 GPIO pins. However, Mothra’s design uses 52 of those pins. The board breaks out eight digital I/O, two analog pins, and access to I2C.