LimiFrog is a Bluetooth 4.1 Wearables Devkit Based on STM32L4 with Lots of Sensors (Crowdfunding)

LimitFrog is a tiny board powered by STMicro STM32-L4 microcontroller with Bluetooth 4.1 connectivity, plenty of sensors, and that can run code bare metal as well as RiOT real-time operating system.

LimifrogLimiFrog specifications:

  • MCU – STMicro STM32-L4 ARM Cortex M4 micro-controller @ 80 MHz with DSP, 512KB flash, 128KB RAM
  • External storage – 8MB serial flash for data that supports FAT32 file system
  • Display – 160×128 RGB565 OLED display
  • Connectivity – Bluetooth 4.1 (Panasonic PAN1740)
  • Sensors (Follow this link for datasheets of most components)
    • Pressure, altitude & temperature (LPS25H)
    • 3-axis accelerometer, 3-axis gyroscope (LSM6DS3)
    • 3-axis magnetometer (LIS3MDL)
    • Ambient light, proximity and distance (VL6180X)
    • Ambient sound (SPU0414H5H)
  • USB – micro USB port for power and programming
  • Expansions – 11-pin (through holes) providing access to SPI, I2C, CAN, PWM, GPIOs, ADC, DAC, Analog out, and power signals (3V out GND)
  • Battery – 500 mAh (hours to weeks of battery life depending on application)
  • Dimensions – N/A (but small)

Limifrog_block_diagramThe “basic” version does not come with sensors, Bluetooth 4.1, nor OLED display, so these are optional, and three more versions are offered “Sense”, “Sense’m comm” and “Full Monty” if you want more features.

LimiFrog can currently be programmed in C/C++, and MicroPython support is in the works. The libraries include a USB stack, a FAT file system, and graphics support. As mentioned in the introduction, programs can run bare metal, or using RiOT real-time operating system.

Software Architecture
Software Architecture

The company also provided a code sample in C if you want to check what the API looks like.

The project has launched on Kickstarter, and rewards start at 39 Euros for the “basic” version of the board with a LiPo battery, software packages, 3D printer files for the case, and up to 99 Euros for the “full monty” including Bluetooth 4.1, the OLED display, and all sensors. Delivery is scheduled for January 2016, and shipping costs between 8 and 12 Euros depending on the chosen rewards. More information may also be found on

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