L476DMW1K – Arm® Mbed™ Enabled IoT Kit


RHOMBIO_L476DMW1K is a kit based on Rhomb.io boards that are ready to build electronic devices that can be connected to Arm Mbed

The kit is composed of:

L476DMW1K is a kit which consists of 4 rhomb.io boards that are ready to build electronic end-devices, this kit runs Arm® Mbed™ OS and will soon be approved to connect to Arm Pelion™ Device Management.
The kit is composed of:

Deimos carrier board is a multi-platform ready-for-product board, with a reduced form factor and Li-Ion battery charger. It has three sockets available: one for a Master module and two for Slave modules, allowing multiple combinations with a number of peripherals/sensors. Also, up to 44 I/O and power pins are accessible for easy connection to a wide range of peripherals.

STM32L476 Master module is a powerful MCU module based on an ultra-low power Cortex-M4+FPU running up to 80MHz. External QSPI, secure element and USB switch are also included.

ESP8266 Slave module, based on the popular and certified WiFi module by Espressif

DAPter module is a removable DAPlink interface, a great tool for flashing and debugging rhomb.io Master modules

The kit is designed for both development purposes and inclusion in complete end-devices ready to be connected to cloud computing platforms. In addition, there is the possibility of adding any type of rhomb.io Slave modules like communications, sensing, storage or any other modules from the catalog. The kit is ready to build, program and install in your product. All kit’s boards are 100% compliant with the rhomb.io ecosystem.


rhomb.io Sockets1x rhomb.io S200 Master Socket
2x rhomb.io Slave Sockets
32-bit ARM Cortex-M4 & FPU, 80 MHz & 32 KHz
Memory1 MB Flash, 128 KB SRAM
16 MB QSPI Flash Memory
Encryption Memory16 Keys/ECDSA/ECDH/SHA-256/SMAC/NIST
ID Memory64-bit Unique-ID Memory with 112 B User EEPROM
Connectivity802.11b/g/n 2.4 GHz, up to 72.2 Mbps
rhomb.io Configuration2xUSB, 3xUART, SPI, 2xI2C, SDIO, QSPI, SAI, CAN, 4xINT, 5xPWM, 26xGPIO, 8xAD
Headers44 signals brought to 2.54 mm headers
PowerUSB Connector
3 LDOs: 3.3V@600mA, 2.8V@300mA, 1.8V@300mA
BatteryBattery Connector
Battery charger with potentiometer: 15 to 500 mA
Dimensions:50 × 49.5 mm
STM32L476 Op. Voltage1.8 V / 2.8 V / 3.3 V
Op. Temperature-25 ºC to +85 ºC



The kit is composed of rhomb.io boards:

  • Deimos – Carrier Board
  • STM32L476 – Master Moduleodule
  • ESP8266 – Slave Module
  • Debug and Programing tool DAPter – Adapter Module

Deimos – Carrier Board

Deimos is a certified Class 2 rhomb.io Carrier Board that allows the creation of electronic devices using exclusively standard rhomb.io modules. It combines the ease-of-use of rhomb.io modules with a reduced form factor, and it has been developed for the Internet of Things (IoT) bearing in mind fast product development. The board also includes a battery management circuit bringing the designer the capacity to make portable devices.

Find more information in the Deimos – Carrier Board datasheet

STM32L476 – Master Module

The STM32L476 is a rhomb.io module that includes the STM32L476 MCU, which is one of the ST Electronics ultra-low-power microcontrollers based on the high-performance ARM Cortex-M4 32-bit RISC core operating at a frequency of up to 80 MHz. The Cortex-M4 core features a Floating Point Unit (FPU) single precision which supports all ARM single-precision data-processing instructions and data types. It also implements a full set of DSP instructions and a memory protection unit (MPU) which enhances application security.

Find more information in the STM32L476 – Master Module datasheet

ESP8266 – Slave Module

The ESP8266 module is a rhomb.io module that delivers highly integrated Wi-Fi solution to meet users’ continuous demands for efficient power usage, compact design and reliable performance in the Internet of Things industry.

This module has been build around the ESP-WROOM-02 module from Espressif. Its complete and self-contained Wi-Fi networking capabilities can be controlled easily by AT commands through the UART interface.

The ESP8266 module integrates a printed circuit antenna with its switches, RF balun, power amplifier, low noise receive amplifier and filters, all of them adjusted to get the best RF performance. The ESP-WROOM-02 is a FCC and CE certified module and you can use it to develop it straight into consumer products.

Find more information in the ESP8266 – Master Module datasheet

DAPter – Adapter Module

The S300 Adapter – DAPter v1.2 is a DAPlink interface for Rhomb.io Master modules. Arm® Mbed™ DAPlink is an open-source software project that enables programming and debugging application software on running on Arm Cortex CPUs. Commonly referred to as interface firmware, DAPLink runs on a secondary MCU that is attached to the SWD or JTAG port of the application MCU. It creates a bridge between your development computer and the CPU debug access port.

Furthermore, thanks to the DAPter, a rhomb.io device can very easily become Arm® Pelion™ Device Ready.

Find out more about Arm® Mbed™ DAPlink on their webpage.

What makes the DAPter module stand out against other DAPlink applications, is that it can be used on any rhomb.io device, it doesn’t matter if it is an early prototype or a product in mass production. Just click the Adapter module between the compatible Master module and the motherboard and as soon as it its turned on, it has all DAPlink capabilities.

Find more information in the DAPter – Adapter Module datasheet


Getting Started

You will need to build your kit up before start coding, if not done yet:

DAPter and ESP8266 modules must be plugged on Deimos board while STM32L476 module must be plugged on top or DAPter board

  • There is a small white triangle on the upper-left corner of any socket on any Rhomb.io carrier board
  • There is a small white triangle on the upper-left corner of any Rhomb.io module
  • Take your Deimos carrier board upside up and look for the small white triangle located on the upper-left corner of Master module socket
  • Take your DAPter board and look for its small white triangle, now plug it on top of Deimos board firmly
  • Do the same with STM32L476 Master module and plug it on top of DAPter board
  • Now take your Deimos board upside down and look for the small white triangle located on the upper-left corner of Slave module socket 1
  • Take your ESP8266 module and plug it on said Slave module socket 1
  • Make sure all three modules have been plugged firmly and properly

You are now ready to connect your RHOMBIO-L476DMW1K to a PC. Take a USB cable and plug it on both the PC and the Deimos’ USB connector, the kit should be detected by the computer as both Mass Storage Device, MSD, and Serial Port (COM/tty)

Now you can drag & drop any .bin file compiled with Mbed OS to the MSD assigned by the PC to your DAPter (e.g: D:). The mbed-os-example-blinky is a great sample code to get started with your RHOMBIO_L476DMW1K and Arm mbed-os.

Try compiling said example and then drag & drop the resulted binary file into the MSD. The two LEDs available on board will start blinking at the same time. Open a serial terminal at 9600 bauds and see all messages being sent by the kit.
































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