Kris Winer has created a pair of Arduino programmable Cortex M4F development boards which fully support the Arduino IDE via USB connections.
The Butterfly and Ladybug STM32L4 boards have been designed to be easy to program yet provide high performance, low-power embedded solutions, says creator. Specifications of the Arduino programmable Cortex M4F Development Boards include :
• Microcontroller: STM32L4 ARM Cortex M4F
• Clock speed: 1, 2, 4, 8, 16, 24, 32, 48, 64, 80 MHz
• Operating voltage: 3.3V
• I/O pin limits: most pins 5.0 V tolerant, 20 mA
• Digital I/O pins: 22, with 11 PWM (Butterfly), 13, with 10 PWM (Ladybug)
• Analog input pins: 6 (Butterfly), 5 (Ladybug), 12-bit ADC channels
• Analog output pins: 2 12-bit DAC
• RTC: 1 ppm accuracy
• Flash memory: 256 KB SRAM: 64 KB
• Voltage regulator: 3.3-5.5V input / 3.3V, 150 mA output
• Dimensions: 1.4 x 0.7″ (Butterfly), 1.1 x 0.6″ (Ladybug)
We designed Butterfly and 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 designed Butterfly and Ladybug for ultra-low-power applications. We chose the NCV8170 150 mA 3V3 LDO because it has a quiescent current of only 500 nA. We included a green power-on led so users could tell when the device was powered but added a solder jumper (on the back) to allow the trace supplying power to the led to be cut and reconnected easily. Even though the led uses a 4700 Ohm current-limiting resistor, it still draws 280 uA, which is a lot when weeks of battery life is required. These are simple development boards to build and use, but we put a lot of thought and features into their design:
– 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!
– No complex software setup needed to deal with ST-Link or JTAG debuggers. Simple Arduino IDE integration via USB/DFU.
– Logical pinmap to comply with the Arduino UNO / Arduino Zero while adding additional UART/SPI/I2C peripherals in a consistent way (Nucleo exposes only 1 UART, 1 SPI and 1 I2C).
– RESET & BOOT buttons for ease of use with traditional tool chains.
– Very low power operation (not possible with Nucleo as the ST-Link is on the same PCB and without it, functionality is seriously limited)
– Tiny form factors, ideal for wearable applications
– 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!)
The only feature missing is ultra-low cost and this is where you come in! Help us meet our Kickstarter goal and we can manufacture these amazing development boards in sufficient quantities to make them very affordable for everyone!
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