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homechevron_rightDocschevron_rightDatasheetschevron_rightBlues Cygnet Datasheet

Blues Cygnet™ Datasheet: Cygnet v1.2

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Cygnet v1.2
Cygnet v1.2

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

Isometric Cygnet image

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 .

Cygnet Feather image

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 #Pin NamePin #Pin Name
RSTRST#----
3V3----
AREF----
GND----
PA0A0BAT
PA1A1PH0EN
PA2A2PB3USB
PA3A3PB4D13
PB1A4PB15D12
PA7A5PB0D11
PA5CKPB13D10
PB5MOPB14D9
PA6MIPB9D6
PA10RXPB8D5
PA9TXPB6SCL
PH3BPB7SDA
PC13USER_BTNPA8LED_BUILTIN

Pin Description Table

Pin NamePin Description (Primary)Voltage Tolerance
A0I/O - GPIO, PWM, ADC5V
A1I/O - GPIO, PWM, ADC5V
A2I/O - GPIO, PWM, ADC5V
A3I/O - GPIO, PWM, ADC3.6V
A4I/O - GPIO, PWM, ADC5V
A5I/O - GPIO, ADC5V
D5I/O - GPIO5V
D6I/O - GPIO5V
D9I/O - GPIO, PWM5V
D10I/O - GPIO, ADC5V
D11I/O - GPIO, PWM, ADC5V
D12I/O - GPIO, PWM, ADC5V
D13I/O - GPIO, ADC5V
SCLI²C - Serial Clock5V
SDAI²C - Serial Data5V
3V3Power - Constant 3.3V Supply-
ENPower - Chip Enable5V
GNDPower - Ground-
RSTPower - Reset-
BATPower - Battery Voltage Supply-
AREFPower - Reference Voltage-
USBPower - USB Voltage Supply-
RXSerial - Receive5V
TXSerial - Transmit5V
BBoot0 - Boot into Bootloader-
MISPI - Main In Secondary Out5V
MOSPI - Main Out Secondary In5V
CKSPI - Serial Clock, DAC3.6V
USER_BTNUser Button-
LED_BUILTINBuilt-in LED-

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

Specifications

Electrical Characteristics

DC Characteristics

DescriptionMinimumMaximumUnit
VIN Supply Voltage2.55.5V
VBAT Supply Voltage2.55.5V
VUSB Supply Voltage2.55.5V
Supply Current0.52.0A
3V3 Output @ 5V1.072.09A

Absolute Maximum Ratings

DescriptionMinimumMaximumUnit
Operating temperature-40125°C

Ordering Information

  • Please visit the Cygnet product page for ordering information.

Design Files

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

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

AuthorDateSummary
Alex R. Bucknall10 DEC 2024Document drafted
Brandon Satrom03 FEB 2025Added Errata for ENABLE_3V3

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

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© 2025 Blues Inc.
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