IoT kit based on Rhomb.io modular system, ready to build electronic devices out-of-the-box. Arm® Pelion™ Device Ready certification coming soon


RHOMBIO_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
  • STM32L476 Master module
  • ESP8266 Slave module (WiFi)
  • DAPter module (DAPlink interface)

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.

Microcontroller features

  • STM32L476VGT6 in LQFP100 package
  • ARM®32-bit Cortex®-M4 with FPU and ART accelerator
  • 80 MHz max CPU frequency
  • VDD from 1.71V to 3.6 V
  • 1 MB Flash
  • 128 KB SRAM
  • GPIOs (114) with external interrupt capability
  • 12-bit ADCs with 16 channels (3)
  • 12-bit DAC channels (2)
  • USART (3)
  • UART (2)
  • LPUART (1)
  • SAI (2)
  • I2C (3)
  • SPI (3)
  • Quad SPI (1)
  • Advance control Timer (2)
  • General purpose Timer (7)
  • Basic Timer (2)
  • Low-power Timer (2)
  • Watchdog Timers (2)
  • CAN (1)
  • Random generator (TRNG for HW entropy)
  • Capacitive sensing (21)
  • Analog comparator (2)
  • Operational amplifier (2)

STM32L476 Master module features

  • STSTM32L476VGT6, 32-bit ARM Cortex-M4 & FPU
  • 80 MHz & 32 KHz, 1 MB Flash, 128 KB SRAM
  • External Memory 16 MB QSPI Flash Memory
  • Secure element 16 Keys/ECDSA/ECDH/SHA-256/SMAC/NIST
  • ID Memory 64-bit Unique-ID Memory with 112 B User EEPROM
  • Other Native USB OTG & USB switch; JTAG/SWD micro connector
  • Rhomb.io Config. 2xUSB, 3xUART, SPI, 2xI2C, SDIO, QSPI, SAI, CAN, 4xINT, 5xPWM, 26xGPIO, 8xAD
  • MCU I/O 82xI/O (12xPWM, 16xADC, 16xINT, 2xSAI, SDIO, QSPI, CAN)
  • Op. Voltage 1.8 V / 2.8 V / 3.3 V
  • Op. Temperature -40 ºC to +85 ºC

/media/uploads/galonso/stm32l476_top_.png /media/uploads/galonso/stm32l476_bottom_.png

Deimos Carrier board features

  • Multi-platform ready-for-product board
  • 1x S200 Master rhomb.io socket and 2x Slave rhomb.io sockets
  • IP67 enclosure available
  • 44 signals brought to 2.54 mm headers
  • UART switch
  • Reset and User buttons
  • Input power: USB connector and solder pads
  • 3 LDOs: 3.3V@600mA, 2.8V@300mA, 1.8V@300mA
  • Battery connector
  • Battery charger with potentiometer: 15 to 500 mA
  • 64-bit Unique-ID Memory with 112 B User EEPROM
  • Op. voltage: 1.8 V to 5.5 V
  • Op. temperature: -25 ºC to +85 ºC
  • Dimensions: 50x49.5 mm

/media/uploads/galonso/deimos_top.png /media/uploads/galonso/deimos_bottom.png

ESP8266 Slave module features

  • Espressif ESP8266EX, 32-bit Tensilica L106, 80-160 MHz
  • 4 MB Flash, 50 KB SRAM
  • 64-bit Unique-ID Memory with 112 B User EEPROM (optional)
  • 802.11b/g/n 2.4 GHz, up to 72.2 Mbps; FCC/CE(RED)/TELEC(MIC)/KCC/SRRC/IC/NCC; WPA/WPA2
  • UART, SPI, I2C, 2xINT, 5xGPIO
  • 12xI/O (4xPWM, 11xINT)
  • 2.8 V / 3.3 V
  • -40 ºC to +85 ºC

/media/uploads/galonso/esp8266_top_-copy-.png /media/uploads/galonso/esp8266_bottom_.png

DAPter module features

DAPter module is a DAPlink interface for Rhomb.io Master modules. Commonly referred to as interface firmware, DAPLink runs on a secondary MCU, the NXP Semiconductors' LPC11U35 microcontroller, that is attached to the SWD port of the target MCU. It creates a bridge between your development computer and the target's debug access port.

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.

DAPter module provides developers with:

  • Drag-and-drop programming (MSC)
  • Virtual serial port (CDC)
  • CMSIS-DAP based debugging (HID)

Furthermore, with the DAPter module, the user can choose which USB port is used for either UART debugging or standard USB port with Master module as host, by simply fitting a jumper on two pins. This way, functionalities of the USB ports switch to one another an viceversa.

/media/uploads/galonso/dapter_top_view_.png /media/uploads/galonso/dapter_bot_view_.png

DAPter's firmware

Latest version of DAPter's firmware (v251): lpc11u35_dapter_rhombio_l476dmw1k_if_crc.bin

Kit pinout

/media/uploads/ppelaez/l476_pin_top_.png /media/uploads/galonso/l476_pin_bot_slaveesp_1_.png

Technical references

For more information, please refer to:

Known limitations

The following section describes known limitations of the platform. Note that general issues are tracked into the mbed repository available on GitHub.

This platform does not present any limitation.

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.

Example applications

Import programmbed-os-example-blinky

This is a very simple guide, reviewing the steps required to get Blinky working on an Mbed OS platform.


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