Cygnet is a low-cost embeddable STM32L4+-based microcontroller board designed to accelerate the development and deployment of battery-powered IoT solutions.

As a lower-cost alternative to the Swan, Cygnet still provides an extensive feature set required for edge-based inferencing and remote monitoring applications. Like its more expensive sibling, Cygnet is designed to be the ideal companion to Notecard while offering a more budget-friendly option.

Functional Description

Cygnet is a Feather-compatible STM32-based MCU, and a lower-cost alternative to our popular Swan MCU. Like the Swan, Cygnet is offered in a Feather standard form factor and uses a STM32L4 part while still providing plenty of flash and RAM to run the majority of your Notecard-powered applications.

Features

• Features of the ST STM32L433CC microcontroller

  • 80MHz Clock speed

  • 256KB Flash, proprietary code readout protection

  • 64KB of SRAM including 64KB with hardware parity check

  • Ultra-low-power with FlexPowerControl

  • 11x timers

  • 16x communication interfaces

  • 14-channel DMA controller

  • Rich analog peripherals (independent supply)

  • True random number generator

• Compliant with the Adafruit Feather Specification

  • Includes a USB-C port for easy power and serial connectivity

  • Includes a PMIC accessible via a JST PH connector, allowing you to either power the board via a LiPo battery and/or recharge the battery via USB.

• USER_BTN programmable button

• LED_BUILTIN programmable LED (red)

• JTAG (SWD capable) debug jack

• BOOT and RESET buttons

• Modular design supports Feather pins or an expansion PCB (to break pins out to 0.1" headers for easier wiring and debugging).

• 10kΩ pull-ups on the SDA and SCL pins

• Qwiic connector

• Notecard Outboard Firmware Update support

Package Configuration

The Cygnet can be used as a Feather-compatible board with soldered male headers, as a part of the Blues Notecard Feather dev kit.

Feather-compatible Cygnet

Out of the box, the Cygnet is usable as a Feather-compatible device.

Pin Information

The following tables contain pin definition mappings between the Cygnet Feather pins to the STM32L433 core MCU.

Cygnet Feather to STM32 Mapping

Pin Description Table

NOTE: All digital I/O pins are interrupt capable.

Specifications

Electrical Characteristics

DC Characteristics

Absolute Maximum Ratings

Ordering Information

• Please visit the Cygnet product page for ordering information.

Design Files

Open source hardware designs for the Cygnet and all Blues hardware are maintained in the note-hardware GitHub repository.

Here are the design files available for the Cygnet:

• Schematic (.pdf) — the full circuit schematic. Use it to understand how the STM32, power, and I/O headers are wired together when designing a compatible host or debugging a connection.
• Bill of materials (.xlsx) — every component with its reference designator and manufacturer part number. Use it to source parts or build your own board.
• PCB drawing (.pdf) — a dimensioned drawing of the board layers, drill details, outline, and mounting-hole locations for reference and mechanical fit.
• Gerber fabrication files (.zip) — the Gerber and drill set. Send this package to a PCB manufacturer to have bare boards produced.
• KiCad project (folder) — the complete, editable KiCad design (schematic sheets, PCB layout, and libraries). Open it in KiCad to modify the design or generate your own outputs.

Cygnet Schematics

The following are a set of interactive KiCanvas-powered schematics of the Cygnet.

Cygnet CPU

Cygnet Feather Connector

Cygnet Power

Board Errata

• The on-board QWIIC connector should only be used when the ENABLE_3V3 signal is HIGH and thus powering the 3V3 pin, as it is by default.

Terms and Conditions

Visit Blues Hardware Terms & Conditions.

Revision History

Contact Information

For other questions about the Cygnet, visit the Blues Forum.

Blues Inc.
https://blues.com
50 Dunham Ridge Suite 1650
Beverly, MA 01915
support@blues.com