Project Documentation

Created 7 project docs

Project Specification

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Project Specification Project Overview
Status: Review
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.

Power Budget

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Power Budget Status and Method
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.

Firmware Getting Started

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Firmware Getting Started Platform and Toolchain
  • MCU: RP2040 U1
  • Framework: Arduino-Pico
  • Build system: PlatformIO
  • Debug: USB serial for logs, SWD through J8 for recovery and source-level debugging
  • Flash: W25Q128JVSIQ external QSPI, 16 MiB
Pin Mapping Recommended Firmware State Machine PlatformIO 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,...

Board Bring-Up Plan

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Board Bring-Up Plan Prerequisites
  • Current-limited bench supply, battery simulator or protected single-cell battery, DMM, oscilloscope, logic analyzer, USB cable, SWD probe, known-good microSD card, LoRa antenna, and optional DHT11/DHT22.
  • Start without battery, SD card, antenna pigtail stress, or external sensor fitted unless the step requires it.
  • Use ESD precautions for U1, U2, U6, MK3, and RF connector J4.
  • Never transmit U6 without an appropriate antenna connected.
  • Initial current limit: 100 mA for static rail checks; raise only after the rail is verified.
1. Visual and Unpowered Inspection
  • Verify orientation and solder quality of U1, U2, U4, U5, U6, D1, Q2, LEDs, and polarized connectors.
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flux

Created and verified seven detailed project files grounded in the current schematic, BOM, PCB layout, firmware history, and enclosure design: - [Project Specification](https://www.flux.ai/:handle/:documentSlug/files/project-specification~yi) - [Power Budget](https://www.flux.ai/:handle/:documentSlug/files/power-budget~hc) - [Firmware Getting Started](https://www.flux.ai/:handle/:documentSlug/files/firmware-getting-started~4w) - [Board Bring-Up Plan](https://www.flux.ai/:handle/:documentSlug/files/board-bring-up-plan~6i) - [Verification and Validation Plan](https://www.flux.ai/:handle/:documentSlug/files/verification-and-validation-plan~dn) - [Technical Construction File](https://www.flux.ai/:handle/:documentSlug/files/technical-construction-file~0n) - [Preliminary Safety FMEA](https://www.flux.ai/:handle/:documentSlug/files/preliminary-safety-fmea~4r) ### Open items - Battery capacity, protection, and permitted charge rate remain unspecified. - Solar-panel rating, recording duty cycle, LoRa interval, and runtime target are unspecified. - The buck-only 3.3 V supply may lose regulation as the Li-ion cell discharges. - SDIO and I²S firmware still require compile-tested library implementations. - Charge current, power consumption, thermal behavior, RF performance, and enclosure fit require physical measurements. ### Suggested next steps 1. Select the battery and solar panel, then finalize the power budget. 2. Run a complete schematic/ERC and power-path review. 3. Implement and compile-test the audio and SDIO firmware. 4. Execute the board bring-up and validation plans on assembled hardware.
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Schematic

Layout

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AvocAudio: v3.2 - Root