Technical Specifications:

• Microcontroller: STM32L432 ARM Cortex M4F
• Clock speed: 1, 2, 4, 8, 16, 24, 32, 48, 64, 80 MHz
• Operating voltage: 3.0V
• Ultra-low-power usage, 1.4 uA in STOP mode!
• I/O pin limits: most pins 5.0 V tolerant, 20 mA
• Digital I/O pins: 13, with 8 PWM
• Analog input pins: 5, 12-bit ADC channels
• Analog output pins: 2 12-bit DAC
• RTC: 1 ppm accuracy
• Flash memory: 256 KB SRAM: 64 KB
• Voltage regulator: 3.3-6.0V input / 3.0V, 200 mA output
• Dimensions: 1.1 x 0.6"

Ladybug (0.6" x 1.1") is a small, low-cost development board with simple, open-source design that will allow just about anyone to make use of the STM32L4 in their own custom applications. Ladybug relies on a single, inexpensive 32.768 kHz crystal oscillator and doesn't require the ST-Link built in to the STM32 Nucleo boards. Applications can be developed using the Ladybug development board, which provide access to all GPIOs and peripherals of the STM32L4. When the application has been sufficiently proved out, application-specific hardware can be designed using the STM32L432 development board as a design template. The 5 mm x 5 mm QFN32 package of the STM32L432 (Ladybug) is space-efficient, low-cost but a still powerful solutions to embedded computational and sensor management problems. Better still, the rich set of low-power modes allows very long battery life in remote and wearable applications.

We designed Ladybug for small LiPo battery operation. There is a port for a JST battery connector on the board as well as a Vin at the board edge that connects to the battery anode so peripherals like haptic motors or displays can be powered directly from the battery, or the board can be directly powered from Vin.

We chose the smallest form factors for the boards to enable use for wearable applications. Ladybug is smaller than most single-cell LiPo batteries!

We chose the TPS7A0230 200 mA 3V0 LDO because it has a quiescent current of only 25 nA.

These are simple development boards to build and use, but we put a lot of thought and features into their design:

(1) Fully-functional USB programming (not indirect through a UART bridge); hence USB/CDC, USB/MSC and USB/HID are supported . USB/MSC means drag and drop files to/from any SPI flash attached to your Butterfly or Ladybug from/to your pc!

(2) No complex software setup needed to deal with ST-Link or JTAG debuggers. Simple Arduino IDE integration via USB/DFU.

(3) Logical pinmap to comply with the Arduino UNO / Arduino Zero while adding additional UART/SPI/I2C peripherals in a consistent way. (STM32L432 Nucleo exposes one UART/I2C/SPI port each to the user).

(4) RESET & BOOT buttons for ease of use with traditional tool chains.

(5) Very low power operation (not possible with Nucleo as the ST-Link is on the same PCB and without it, functionality is seriously limited)

(6) Tiny form factors, ideal for wearable applications

(7) Open Source. Simple and easy-to-build hardware designs and easy to use with any software layer (try using an Arduino Zero without an Arduino IDE!)