A compact, battery-powered tinyML audio and environmental data-collection board based on the RP2040. The device records digital microphone data to microSD, can attach a DHT11/DHT22 sensor, and reports status or summarized data over LoRaWAN through a LoRa-E5 module. It supports USB or solar-assisted charging of a single-cell Li-ion/Li-polymer battery and is packaged in a two-piece FDM enclosure.
Intended Use
Community development and field data collection for tinyML audio applications.
Local audio capture and storage where Wi-Fi is unavailable.
Periodic low-bandwidth LoRaWAN telemetry rather than streaming raw audio over LoRa.
Prototype and validation platform; the current revision is not yet production-qualified.
Status: Preliminary engineering budget for review. It is grounded in the live schematic, but several load currents are planning allowances because the exact SD card, DHT sensor, firmware duty cycle, battery, and solar panel are not selected.
The power path is:
Confirmed Electrical Facts
Main regulated system rail: +3V3.
Internal RP2040 core rail: +1V1, generated by the RP2040 internal regulator.
Battery rail: VBAT, a single Li-ion/Li-polymer cell charged to 4.2 V by U5.
Charge-current intent: approximately 900 mA according to the schematic annotation and R7 = 2 kOhm.
U4 RT8059 is rated in project component data as a 1 A buck converter with 2.8 V to 5.5 V input.
Debug: USB serial for logs, SWD through J8 for recovery and source-level debugging
Flash: W25Q128JVSIQ external QSPI, 16 MiB
Pin MappingRecommended Firmware State MachinePlatformIO Configuration
The exact Arduino-Pico release and SDIO/I2S libraries must be pinned after a compile-tested implementation. The microSD wiring is 4-bit SD, not conventional SPI; do not silently substitute an SPI example without rewiring hardware.
Initial Bring-Up Source
This source is intentionally limited to peripherals that can be initialized with stable Arduino-Pico APIs from the confirmed schematic: USB logging, user LED, DHT, LoRa UART/reset,...