Swan is a low-cost embeddable STM32L4+-based microcontroller board designed to accelerate the development and deployment of battery-powered IoT solutions.
It is especially useful for applications requiring large memory or a high degree of I/O expandability at an affordable cost, such as edge-based inferencing and remote monitoring. Acting in this role, Swan is designed to be the ideal companion to Blues's Notecard.
The Swan is a Feather-compatible MCU based on the STM32 from STMicroelectronics. The device was built after Blues worked directly with a customer to implement a complex industrial modernization solution based around the Notecard. It is designed to operate as a device that developers can get started with quickly as a Feather for a POC or Prototype. Once developers are ready to move into a Pilot, or the complexity of the solution demands it, the Swan can leverage an additional 36 pins from the STM32 MCU through a set of castellated edges on the main PCB to utilize additional GPIOs or buses like I2C, UART, SPI, and CAN.
Features of the ST STM32L4R5ZIY6 microcontroller
120MHz Clock speed
2MB Flash, 2 banks read-while-write, proprietary code readout protection
640KB of SRAM including 64KB with hardware parity check
Ultra-low-power with FlexPowerControl
20x communication interfaces
14-channel DMA controller
Rich analog peripherals (independent supply)
True random number generator
Compliant with the Adafruit Feather Specification
includes a Micro-USB 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.
Access to 36 additional STM32 pins (beyond the Feather pins) via 0.05" castellated edge headers
LED_BUILTINprogrammable 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
The performance of the STM32 microcontroller onboard the Swan may be affected in the presence of extremely bright light including, for example, direct sunlight. Bright light may interfere with the semiconductor's operation by generating unwelcome electrical currents, performance degradation, malfunction, or shutdown.
If you anticipate that bright light may shine on your device in its deployed setting, we recommend you mount the device in a shadow, or that you cover the STM32 microcontroller with an opaque tape to reduce light levels that may affect the semiconductor.
The Swan can be used as a Feather-compatible board with soldered male headers, as a part of the Blues Notecard Feather dev kit, or as a headerless PCB with base carrier board for accessing 55 IO pins on the core STM32L4R5 MCU.
The Swan comes from the factory with no headers and a castellated edge, which allows it to be embedded directly in almost any project.
Use the included male Feather header pins to use the Swan as a Feather-compatible device.
The Swan Carrier board is designed to breakout the connections along the castellated edge of the Swan board. Once the Swan has been soldered directly to the carrier board, then additional dual row headers can be soldered
The following tables contain pin definition mappings between the Swan and Carrier pins to the STM32L4R5 core MCU.
|Pin #||Pin Name||Pin #||Pin Name|
|Pin #||Pin Name||Pin #||Pin Name||Pin #||Pin Name||Pin #||Pin Name|
|Pin Name||Pin Description|
|A0||I/O - GPIO, PWM, ADC|
|A1||I/O - GPIO, PWM, ADC|
|A2||I/O - GPIO, ADC|
|A3||I/O - GPIO, ADC|
|A4||I/O - GPIO, ADC|
|A5||I/O - GPIO, ADC|
|A6||I/O - GPIO, PWM, ADC|
|A7||I/O - GPIO, ADC|
|D0||I/O - GPIO|
|D1||I/O - GPIO|
|D2||I/O - GPIO|
|D3||I/O - GPIO, PWM|
|D4||I/O - GPIO, PWM|
|D5||I/O - GPIO, PWM|
|D6||I/O - GPIO, PWM|
|D7||I/O - GPIO,|
|D8||I/O - GPIO|
|D9||I/O - GPIO, PWM|
|D10||I/O - GPIO, ADC, DAC1|
|D11||I/O - GPIO, PWM, ADC|
|D12||I/O - GPIO, PWM, ADC|
|D13||I/O - GPIO, PWM, ADC, DAC2|
|D14||I/O - GPIO, PWM|
|D15||I/O - GPIO, PWM (*)|
|SCL||I²C #1 - Serial Clock|
|SDA||I²C #1 - Serial Data|
|SCL2||I²C #2 - Serial Clock|
|SDA2||I²C #2 - Serial Data|
|SCL3||I²C #3 - Serial Clock|
|SDA3||I²C #3 - Serial Data|
|3V3||Power - Constant 3.3V Supply|
|EN||Power - Chip Enable|
|GND||Power - Ground|
|RST||Power - Reset|
|VBAT||Power - Battery Voltage Supply|
|VIN||Power - Input Voltage|
|VUSB||Power - USB Voltage Supply|
|RX0||Serial #0 - Receive|
|TX0||Serial #0 - Transmit|
|CTS||Serial #1 - Clear to Send|
|RTS||Serial #1 - Request to Send|
|RX||Serial #1 - Receive|
|TX||Serial #1 - Transmit|
|CTS2||Serial #2 - Clear to Send|
|RTS2||Serial #2 - Request to Send|
|RX2||Serial #2 - Receive|
|TX2||Serial #2 - Transmit|
|CTS3||Serial #3 - Clear to Send|
|RTS3||Serial #3 - Request to Send|
|RX3||Serial #3 - Receive|
|TX3||Serial #3 - Transmit|
|CS||SPI - Chip Select|
|MISO||SPI - Main In Secondary Out|
|MOSI||SPI - Main Out Secondary In|
|SCK||SPI - Serial Clock|
|QCLK||Quad SPI - Serial Clock|
|QCS||Quad SPI - Chip Select|
|QEN||Quad SPI - Enable|
|QIO0||Quad SPI - Bit 0|
|QIO1||Quad SPI - Bit 1|
|QIO2||Quad SPI - Bit 2|
|QIO3||Quad SPI - Bit 3|
NOTE: All digital I/O pins are interrupt capable.
(*) Not supported on CircuitPython, since it relies on Timer 17, with 16 being the maximum supported.
- Please visit the Swan product page for ordering information.
Open source hardware designs for the Swan and all Blues Hardware are maintained in the note-hardware GitHub repository.
3V3pins on the Swan Feather board do not conform to the Adafruit Feather spec and are reversed. While still mechanically functional even in many FeatherWings, customers should be aware of this orientation in case issues arise in development.
The Swan Feather I2C
SCLpins do not include pullup resistors. I2C devices that do not include their own pullups will need to have these added in order to communicate with Swan.
|Zachary J. Fields||28 JUL 2021||Document drafted|
|Brandon Satrom||29 SEP 2021||Final Edits for publication|
|Zachary J. Fields||20 OCT 2022||Swan v3.0 Updates|
|Rob Lauer||2 FEB 2023||Warning re: STM32 light sensitivity|
For other questions about the Swan, visit the Blues Forum.